IH Exam 2

11. Re-evaluate Health Limits

• After modifications of the hot work, it should be re-evaluated using the previous methods • OELs do not represent upper limits for working in the heat, but they imply that risk for heat stress is increasing and controls should be implemented • If heat stress is still considered to be excessive, personal physiological monitored is recommended

Risk Assessment

• Agent-based - Pathogenicity, Infectious Dose, Environmental Stability, Route of Transmission • Activity-based - Laboratory equipment & procedures - Quantity and concentration of agent - Facilities and controls in place - Human host factors

Types of Controls for Thermal Stress

• Administrative Controls • Worker Selection • Worker Training • Scheduling • Work-Rest Intervals • Job Rotation • Engineering • PPE

IR Radiation

• Skin absorbs IR as heat = warning mechanism - Except the eyes • Far, middle and near IR can penetrate the cornea • ACGIH TLV intended to prevent cataracts - Glass blower's or furnace man's cataracts • Measurement: light meter with IR filter

Sound Pressure

• Sound is a slight, rapid variation in atmospheric pressure • Units of Sound pressure are units used to quantify pressure (Pascal, N/m2, bar etc). • For humans difference between smallest sound (approx 20 µPa—threshold of hearing) and largest sound (20 Pa— threshold of pain) is 10,000,000 times greater.

Sound Waves

• Sound waves are elastic waves and can only occur in media that have the properties of mass (inertia) and elasticity. Refraction Pressure Wave

Electrical Power Transmission

60hz 765kV - 115kV DC stepping down to AC

Potassium-40, Iodine-131 and Cobalt-60 are all emitters of which type of radiation?

Gamma and X-rays

Evaluating a Cold Workplace

1. Preliminary Review 2. Decide Type of Analysis 3. Measure the Thermal Environment 4. Determine Windchill Index 5. Estimate Metabolic Heat 6. Determine Insulation Required 7. Modify the Hot Work Exposure

Air Changes Per Hour (ACH)

Assuming the air is uniform/perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced per hour ACH = Q*(60/Vroom) ACH = Air changes per hour Q = Flow rate (ft3/min or cfm) Vroom = Volume of the room (ft3)

Which Biosafety Level Containment should you use when handling Hepatitis A?

BSL-2

What is the OSHA standard for microwave radiation?

10 mW/cm2 over 6 min

Nuclear Level Gauges

Scintillation spectroscopy

• Occupational hearing loss is defined as

- "a hearing impairment of one or both ears, partial or complete, arising in, or during the course of, but as the result of one's employment." - Acoustic Trauma (usually single incident) - Noise-Induced Hearing loss (cumulative loss)

- Route of transmission

- Infective dose - Environmental stability - Availability of vaccine or treatment Routes of Transmission • Direct Contact • Skin, eye, or mucous membrane exposure • Parenteral Inoculation • Contaminated sharp, animal or arthropod bite • Ingestion • Mouth pipetting, hand-to-mouth exposure • Inhalation of infectious aerosols

Cosmic Radiation

-consists of x-rays, protons, alpha particles, electrons, muons, and neutrons -risk based on geomagnetic field, altitude and solar cycle -military, civil and commercial aircraft crews at greatest risk of exposure

Acute Dose Effect (rad)

0-25 No observable effect 25-50 Minor temporary blood changes 50-150 Nausea, vomiting, reduced WBC 150-300 Severe diarrhea, malaise, loss of appetite Some death 300-500 Symptoms appear sooner > 500 LD100 = 600 rad

relative humidity

• keep RH within the minimal growth zone -Room air & HVAC air may differ

Laser Classes

1 Safe - no label required. 2 Visible laser. Aversion response protective. Don't stare. 3a Visible laser. Limit eye exposure. No magnifying optics. 3b Max 500 mW. All frequencies. No eye exposure. 4 >500 mW. All frequencies. No eye/skin exposure. Fire hazard. Hazard from diffuse reflections.

ICRP (International Commission on Radiological Protection) Guidelines

1. "The justification of a work practice: No work practice involving exposure to ionizing radiation should be adopted unless it produces sufficient benefit to the exposed individual of the society to offset factors being taken into account." 2. "The optimization of a work practice: All radiation exposures must be kept as low as reasonably achievable (ALARA), economic and social factors being taken into account." 3. The individual dose limits: The radiation dose from all relevant sources should not exceed the prescribed dose in the following table." Effective dose In a single year 5 rem Annual equivalent dose Hands & feet 50 rem Embryo-fetus exposures Monthly equivalent dose 0.05 rem

Evaluating a Hot Workplace

1. Preliminary Review 2. Select a Heat Index 3. Select Instruments 4. Measure the Thermal Environment 5. Calculate the WBGT 6. Calculate the WBGT-TWA 7. Estimate Metabolic Heat 8. Evaluate Recommended Limits 9. Determine Thermal Components 10. Modify the Hot Work Exposure 11. Re-evaluate Health Limits

Evaluating a Cold Workplace

1. Preliminary Review • Observe work site: • Type of work • Thermal characteristics • Type of clothing • Other relevant job/worker characteristics • Review records of previous cold-related injuries/illnesses • Review climatic records may be useful 2. Decide Type of Analysis • Simple/general approach vs detailed/rational analysis • General approach is generally recommended: • Less measurement • More estimates • Use of tables for decision making • Basic equations of thermal balance can be used to environmental measurements 3. Measure the Thermal Environment • Air temperature (ta) • Wind speed (v) • 2 m/s Light flag moves • 4 m/s Light flag fully extended • 7 m/s Newspaper raised • 9 m/s Blowing/drifting snow • Information from National Weather Service may be appropriate • For detailed analysis, measure mean radiant temperature and humidity • Surface temperature should be measured when bare skin/hands might contact cold surfaces (e.g., using a surface thermistor) 4. Determine Windchill Index • What is the wind chill index for the following conditions: • Air temperature = -18 °C • Air velocity = 7 m/s WCI = 13.12 + 0.6215TWCI = a - 11.37(-16.4Var0.16) + 0.3965(Var0.16) • Would you recommend that exposed skin be covered in this case? 5. Estimate Metabolic Heat ->Same as for heat stress 6. Determine Insulation Required • IREQ (Required Clothing Insulation) can be calculated for a specific environment if various conditions are known. • IREQ is not exactly the same as the clothing insulation (clo) value normally provided for clothing. • For the previous example of moderate work at -18 °C, what IREQ would be recommended? 7. Modify the Cold Work Exposure • Training • Local/personal heaters • Clothing • Mechanization • PPE (esp. for head/extremities) • Scheduling • Proper selection of • Worker rotation tools/equipment • Work breaks • Shielding • Buddy system • Heated enclosures

What is the OSHA PEL for whole body radiation exposure?

1.25 rem/quarter Although 1.25 rem/quarter = 5 rem/yr, the standard is based on maintaining exposure below the quarterly exposure.

Convert the following for exposure to x-ray radiation : 350 mrem = _____ rad (mrem to rad)

100 mrem = 0.1 rad so 0.35(with margin: 0)

Which of the following is the TLV-C for noise exposure?

140 dB The TLV-C is the ceiling limit. According to ACGIH, the TLV for noise is a maximum of 140 dB.

BLOOD BORNE PATHOGENS

29 CFR 1910.1030 5.6 million workers in health care and related industry at risk of exposure to blood borne pathogens. PURPOSE Limits occupational exposure to blood and other potentially infectious materials. SCOPE All employees "reasonably anticipated" to incur occupational "skin, eye, mucous membrane, or parenteral contact" as the result of performing their job duties to contact blood and other potentially infectious materials. Blood: Human blood, blood products, or blood components. Other Potentially Infectious Materials: Saliva, semen, vaginal secretions, cerebrospinal, synovial, pleural, pericardial, peritoneal and amniotic fluids, body fluids visibly contaminated with blood, unfixed human tissues or organs, etc. I. EXPOSURE CONTROL PLAN (Infection Control Plan) • Written • Must be accessible to employees. • Must be updated at least annually. II. EXPOSURE DETERMINATION • Tasks and Procedures at risk of exposure • Job classifications at risk of exposure III. CONTROL METHODS • ENGINEERING Puncture-resistant, leak-proof containers • UNIVERSAL PRECAUTIONS Treating all body fluids/materials as if infectious. • WORK PRACTICE CONTROL Hand washing facilities Standard microbiological practices Housekeeping Infectious waste management/disposal Laundry • PERSONAL PROTECTIVE EQUIPMENT gloves gowns masks mouth pieces resuscitation bags IV. PROCEDURES FOR INVESTIGATING EXPOSURE INCIDENTS V. HEPATITIS B VACCINATION • Make available (at no cost) to all employees who have occupational exposure within 10 working days of assignment. VI. POST-EXPOSURE EVALUATION AND FOLLOW-UP • Specific procedures made available to all employees who have had an exposure incident. VII. HAZARD COMMUNICATION • Warning tags and labels • Biohazard symbols • Red bags • Signs for restricted areas VIII. INFORMATION AND TRAINING • Within 90 days initially and annually • Opportunity for question and answers • Records kept for duration of employment plus 3 years. - Explain regulation - Explain disease transmission and symptoms - Explain modes of transmission - Explain written exposure control plan - Describe methods to control disease transmission - Explain how to recognize occupational exposure - Explain the free Hepatitis B Vaccinations (efficacy, safety, benefits, administration) - Explain procedures for reporting exposures - Explain post-exposure evaluation and follow-up - Describe PPE, administrative and engineering controls - Explain labels, signs, and color coding IX. RECORD KEEPING • Records kept for duration of employment plus 30 years. • Confidential • Hepatitis B vaccination status and dates. • Examination

EXAMPLE #2: Calculate WBGT-TWA WBGT measurements at a work site show the following exposures. Calculate the WBGT-TWA.

30-minute at 30ºC 20 minute at 28ºC 10 minute at 38ºC. WBGT-TWA = (T1 x WBGT1+ T2 x WBGT2 + T3 x WBGT3) / TTotal WBGT-TWA = (30 min[30ºC] + 20 min[28ºC] +10 min[38ºC]) / 60 min = (900 + 560 + 380) / 60 WBGT-TWA = 30.7 ºC

Which of the following is a typical annual background exposure to radiation

300 mrem Typical background radiation exposure is on the order of 300 mrem annually for the general population. Other factors will also affect this number, such as altitude, geology, medical procedures etc.

What is the frequency of sound with a wavelength (λ) equal to 10 m?

34.4 Hz c = wavelength * frequency 344 m/s / 10 m = 34.4 Hz

• EXAMPLE:

A worker is carrying/stacking heavy boxes (work load of 390 watts). This task requires 15 min of rest (15 watts) for every 45 min of work. What is the best estimate of metabolic rate? = 390 + 15 = 405 W

A worker has an 8-hour TWA noise exposure of 90 dBA. What is the resulting sound level for this worker after utilizing formable ear protection with a Noise Reduction Rating (NRR) of 24, based on the NIOSH adjusted level?

81.5 dB Lp = 90 - (24-7)*0.5 Lp = 90 - 8.5 Lp = 81.5 dB

Which of the following represents a 50% noise dose (over 8 hours), according to ACGIH?

82 dB The ACGIH TLV for an 8-hour noise exposure is 85 dB, with a 3 dB exchange rate. That means that 50% of the TLV is 85 - 3 dB = 82 dB.

At which noise exposure level does a Hearing Conservation Program need to be implemented?

85 dB OSHA requires a Hearing Conservation Program when the noise exposure is greater than 85 dB, which represents an Action Level at a 50% dose.

A worker is exposed to 85 dBA for 5 hours, 100 dBA for 1 hour and 70 dBA for 2 hours during an 8-hour shift. What is the 8 hour TWA according to OSHA?

88.5 dBA To calculate the TWA, first calculate the dose (%) using the OSHA allowed duration. The 70 dB exposure can be excluded. (5/16 + 1/2 + 0) *100 = 81.3% dose TWA = 16.61*log (81.3/100)+90 = 88.5 dBA

Sound pressure levels measured independently for four industrial generators were 87 dBA, 85 dBA, 91 dBA and 92 dBA. Assuming these generators are to be located in close proximity to each other, what is the resultant sound pressure level when all four generators are in operation?

96 dBA Lp = 10 log (108.7 + 108.5 +109.1 +109.2) = 95.6 dB or 92-91=1 so 92+3 = 95 95-87=8 so 95+1 = 96 96-85=11 so 96+0 = 96 dB

Which of the following weighted responses simulates sensitivity of the human ear at moderate sound levels?

A-weighted A-weighted response slightly reduces the weight of low frequency sounds and slightly increases that of high frequency sounds. C-weighted response simulates sensitivity of human ear at high sound levels.

6. Calculate the TWA for WBGT

A. What is the TWA for a worksite with the following WBGT measurements: 40min @35C 20min @28C WBGT-TWA = ((40*35)+(20*28))/80C WBGT-TWA =32C B. recommend 20 minutes @ 30 °C

5. Calculate the WBGT

A. What is the WBGT for an indoor workplace with the following temperature readings: Tdb = 35°C Tnwb = 30°C Tg = 39°C B. What is the WBGT for an outdoor workplace with the following temperature readings: Tdb = 33°C Tnwb = 25°C Tg = 35°C

Quantitative Assessment: "Dust"

Aerosol Spectrometers Filter Cassettes Cascade Impactor

Which of the following types of radiation is most easily shielded (e.g. with skin or paper)?

Alpha Alpha radiation is the most easily shielded, e.g., by skin or paper. Therefore, it is primarily an internal (inhalation) hazard.

Survey Instruments

Alpha: Proportional or scintillation counters Beta, Gamma: Geiger-Muller or proportional counters X-ray, Gamma: Ionization chambers Neutrons: Proportional counters

absorbed does equivalent to a unit does equivalent

Alpha: 1 Xray, gamma, beta = 0.05 neutron of unknown energy = 0.1 high-energy proton = 0.1

What is the Quality Factor (Q) for alpha radiation?

Alpha: 20 Xray, gamma, beta = 1 neutron of unknown energy = 10 high-energy proton = 10

Biohazard Containment

Biosafety Levels, designated as BSL1, BSL2, BSL3, BSL4, ABSL1, ABSL2, ABSL3, ABSL4 - Consist of combinations of laboratory practices, containment equipment, and laboratory design. - Based on the potential hazards imposed by the agents used.

For which of the following occupations would you be most concerned about exposure to IR radiation?

Boiler operator

Which of the following are target organs of UV radiation? Select all that apply.

Brain Skin Lungs Cornea

TUBERCULOSIS

CDC GUIDELINES FOR PREVENTING TB TRANSMISSION IN HEALTH CARE FACILITIES 59 CFR 54242 (October 28, 1994) OSHA only conducts TB inspections in response to employee complaints or at CDC identified highincidence facilities. M. Tuberculosis is carried in airborne particles, or droplet nuclei (1-5 um), that can be generated when persons who have pulmonary or laryngeal TB sneeze, cough, or speak. Occupational settings of most concern: - health care facilities - prisons - homeless shelters - long-term care facilities for the elderly - drug treatment centers IDENTIFY, ISOLATE, TREAT Environmental Factors Enhancing Transmission: • Exposure in relatively small, enclosed spaces • Inadequate local or general ventilation that results in insufficient dilution and/or removal of droplet nuclei - negative pressure - filtration - UV lights - > 6 air changes per hour (where feasible > 12 ach) • Recirculation of air containing infectious droplet nuclei - No recirculation of air in TB isolation rooms - High efficiency particulate air filters (HEPA) UV lights in upper rooms or air ducts

Electromagnetic Waves

Characterized by: • Electric & magnetic field strengths (amplitude). • Wavelength (: one complete sinusoidal wave). • Frequency (f: Hz or cycles per second). • Photon energy (E). • As decreases, f & E increase. • Voltage produces the electric field: - Measured in volts/meter (v/m). • Current produces the magnetic field: - Measured in Tesla (T: International) or Gauss (G: U.S.).

Which of the following is a possible source of ionizing radiation?

Cigarette Smoke Nuclear power plant CAT Scan Bananas All of the above

Quantitative Assessment: Gas & Vapor

Colorimetry Gas chromatography mass spectrometry Summa canister (GC/MS) Photoionization

Sick Building Syndrome

Complex symptoms. • Nasal irritation, sinus congestion, headache, fatigue & lassitude, headaches, dry skin, dizziness, etc. Subjective symptoms. • Possible psychosomatic symptoms: • Symptoms vary. Typically subjective. Stress-related? Epidemic prone? • Multiple chemical sensitivity: • Symptoms similar to SBS. Free of immunological disease? Subjective symptoms? • Lack of comfort: • Thermal, relative humidity & odor discomfort. Variability in population.

Dose & TWA

D (%) = [C1/T1 + C2/T2 ...+ Cn/Tn]*100 D = equivalent dose (described as %) Cn = exposure time at given noise level Tn = allowed time at that noise level *Do not include exposures <80 dBA in the calculation TWA = 16.61 x log10(D/100) + 90 dBA

CO2 as a Ventilation Surrogate

Demand control ventilation (DCV) uses inline CO2 monitors to determine the volume of outside air needed to maintain 15 cfm/person.

Semiconductor Manufacturing

Dielectric film deposition: "Sputter"

NRC Exposure Standards • NRC Table 20.1201 Occupational Dose Limits for Adults

Dose Equivalents: Annual Limit Portion of Body Dose per Time Period Total Dose 5.0 rem, 0.05 Sv Lens of Eye 15.0 rem, 0.15 Sv Skin of body 50 rem, 0.5 Sv Skin of Extremity 50 rem, 0.5 Sv

Multiple Sound Sources

Due to log scale, we can't just sum contribution of multiple sources for Total L = combined sound press level (SPL) Ln=SPL for source 1, 2, ...n

In the US, 60 Hz is the frequency of EMF in our home electrical system. What type of EMF radiation is this?

ELF

Which organization provides the primary guideline for exposure to radon?

EPA sets the radon guideline to 4.0 Pci/L for inhabited buildings.

Contributing Factors to sick building syndrome

HVAC design Occupant density Building design Workplace stress Physical health Employee Building materials Work activities Complaints & Health HVAC ops. & main. Mental health Geography Labor relations Building maintenance

Which of the following controls would not be useful for non-ionizing radiation?

Half face respirator for IR radiation

What is the main health effect of non-ionizing radiations?

Heating of body tissues

Shielding Effectiveness Intensity on the other side of the shield:

I = Io Be-x Io = original intensity = linear absorption coefficient X = shield thickness (same units as ) B = radiation scatter

distance

Intensity Near a Source The effect of distance can be estimated from the following: D = A/d2 D = Exposure rate (R/hr) = Specific gamma ray contamination units R-m2/mCi-8 Hr d = distance from source in cm A = Activity in mCi of the isotope

entrainment HVAC

Introduction of gaseous contaminants into HVAC System: CO, NOx, etc. Normally occurs due to poor design/location of air intakes.

Which of the following is characteristic of a virus?

It cannot carry out life functions independently

Radiation PPE

Level and type of PPE dependent on type, intensity and duration of exposure. • Skin or internal hazard? Whole body irradiation? • Air-purifying respirators use radiation-specific cartridges.

Exposure Assessment Instrumentation

No one device measures both fields and all frequencies. Conduct quantitative assessment to determine which instruments are needed.

Exposure Standards & Guidelines

OSHA Body part: Allowable dose per quarter Whole body; head & trunk; active blood-forming organs; eyes; or gonads 1.25 rem = 5 rem/yr (recommended: 2 rem/yr) Hands & forearms; feet & ankles 18.75 rem Skin of whole body 7.5 rem Total life accumulation 5 x (N - 18) rem; N = age Restricted areas 200 mrem/hr MSHA 1 Working Level Month (WLM = 1.3 x 105 MeV alpha for one month) ACGIH Endorse International Commission on Radiological Protection (ICRP)

Which of the following controls are typically utilized in a Biosafety Level 2 Laboratory?

PPE including gloves, eye protection and a lab coat

Toxoplasmosis is which type of biological hazard?

Parasite Toxoplasmosis is a result of the Toxoplasma gondii parasite. It is spread from contaminated cat feces.

Magnetic Field Shielding

Personnel booth Shielding film Full enclosure MuMetal deflector

Which of the following is NOT an optical radiation?

RF

RF Dielectric & Microwave Heaters

RF Sealer/"Welder"

U-238 Decay

Radon gas is odorless, colorless and easily exhaled, but it's progeny () particles which are toxic. The alpha particles from radon attach to dust particles and are inhaled through normal respiration. Deposition in a specific region of the respiratory tract is dependent on the particle size.

HVAC re-entrainment:

Recapture of exhausted contaminants Due to poor design location of exhaust stack in relation to air intakes.

Inductive Heating & Processing

Refining converter Melting furnace

Which of the following uses of PPE for radiation is inappropriate?

Respirator to prevent exposure to gamma radiation Respiratory protection for radiation is only relevant for possible inhalation exposure hazards, such as from alpha radiation.

Which of the following represents a control typically only used for Biosafety Level 4 Laboratories?

Supplied-air suits

EXAMPLE #1: Calculating WBGT Assume the temperature readings obtained at an indoor workplace were as follows. Calculate the WBGT temperature.

Ta = 35 ºC Tnwb = 30 ºC Tg = 39 ºC WBGT = 0.7 Tnwb + 0.3 Tg = 0.7 (30 ºC) + 0.3 (39ºC) = 21.0 + 11.7 WBGT = 32.7 ºC

Tinnitus is an example of which type of hearing loss?

Sensorineural

Which of the following does NOT represent a potential parenteral exposure?

Skin contact A parenteral exposure is often thought of as an "injection" exposure, either subcutaneous, intravenous or intramuscular.

Key Radioisotopes

Sodium-22 2.6 yr 0.54 MeV +; 0.51 & 1.27 MeV high & dose rates Iron-55 2.7 yr Various low energy x-rays & Auger electrons (<6 keV) does not present a significant external hazard Cobalt-57 271.8 days (< than 0.13 MeV) Cobalt-60 5.3 yr 0.31 MeV ; 1.17 & 1.33 MeV high and dose rates Nickel-63 100 yr 0.066 MeV does not present a significant external hazard Strontium-90 29.1 yr 0.54Mev (Y-90) decays to short-lived Y-90; very high dose rates Cesium-137 30.1 yr 0.51 MeV ; 0.661 (Ba-133m) decays to short-lived Ba- 133m Polonium-210 138.4 days 5.3 MeV does not present a significant external hazard Radium-226 1600 yr 4.8 MeV ; various , and from decay products decays to Rn-222, with a long decay chain following Americium-241 432.7 yr 5.6 MeV ; various alphas, and from decay products decays to long-lived Np-237, decaying in turn to Pa-233 and U-233. emissions are the greatest concern.

Heat Stress Index (HSI)

The HSI assumes that there is no storage of heat in the body at the beginning of heat exposure, and thermal exchanges by conduction and respiration can be ignored. Ereq = M + R + C where M = metabolic heat R = radiant heat C = convective heat • The equations and coefficients needed to compute the values of R, C, Emax, Ereq, and HSI for various combinations of clothing are available. • The HSI does not correctly differentiate between heat stress resulting from a hot, dry climate and that resulting from a warm, damp climate.

absorbed dose

The energy imparted by ionizing radiation per unit mass of irradiated material. The units of absorbed dose are the rad and the gray (Gy)

Which of the following best describes the inverse square law?

The intensity of radiation from a source increases proportionally to the square of the change in distance Intensity = 1/d^2

What is the "universal precaution" associated with blood borne pathogens?

Treat all body fluids/materials as if infectious

EMF Measurement

Two types of instruments: • broadband survey meters: senses any signal across a wide range of frequencies and is usually made with three independent diode detectors • Frequency selective meters: consists of a field antenna and a frequency selective receiver or spectrum analyzer allowing to monitor the frequency range of interest.

Quantitative Assessment: HVAC

Volumetric Balometer anemometer anemometer Thermal Imaging Hot-Wire

UV Emissions

Welding Sunlight food packaging: UV Emissions Package sealing

Which of the following are possible sources of RF radiation?

Welding Radar TV signals Furnace Sunlight Bluetooth

NRC Exposure Standards NRC Table 1004(b).1 - Quality Factors and Absorbed Dose Equivalencies

X-ray, Gamma, or beta radiation Q=1 Absorbed dose equivalent to a unit dose equivalent = 1 Alpha particles, multiple-charged particles, fission fragments 20 0.05 Neutrons of unknown energy 10 0.1 High-energy protons 10 0.1

Which of the following is NOT a potential biological hazard?

a chlorine spill Although often wrongly referred to as a "biohazard," a chemical spill is not typically a biological hazard. When we talk about biological hazards in the occupational health field, we are referring to agents capable of interacting with living cells/tissues and as a result of that interaction propagating itself or its effects.

X-Ray & Gamma Interaction

compton effect photoelectric effect pair production

There is abundant evidence that non-ionizing radiation causes cancer.

false

Most bacteria are harmful to humans.

false In fact, very few bacteria cause infection in humans.

Which of the following hearing protection devices requires the a 50% reduction in the NRR in order to calculate the adjusted noise exposure level?

formable earplugs Formable: -50% Muffs: -25% Premolded: -70%

Which of the following is an environmental factor that enhances transmission of tuberculosis?

inadequate ventilation Inadequate local or general ventilation may result in insufficient dilution and/or removal of droplets.

Ionizing and non-ionizing radiation, including their effects on the human body

non: Heating of body tissues ion: direct tissue damage and cancer. radiation burns, radiation sickness, organ failure, and even death can affect the atoms in living things, so it poses a health risk by damaging tissue and DNA in genes. has sufficient energy to affect the atoms in living cells and thereby damage their genetic material (DNA).

What is the SI unit for dose equivalent of ionizing radiation?

sievert

Average US Exposure Profile

~ 300 mrem/yr Key Exposure Determinants • Frequency, magnitude & variability of exposure and tasks. • Route(s) of exposure. • Short-duration tasks and exposures. • Long-term or frequently repeated tasks and exposures. • Adequacy and potential for failure of engineering and work practice controls.

Examples of Thermal Stress

• A cold environment may increase the risk of cumulative trauma disorders. o Worker performance deteriorates during cold stress before physiological limits have been reached. o Hand dexterity begins to decrease when skin temperatures fall to 15-20°C (59- 68°F). o Muscle strength declines when muscle temperature falls below 28°C (82°F). • A warm environment can compromise the concentration, steadiness, or vigilance of workers. o Even moderately warm environments may require interruption of work with extensive rest breaks, especially when protective clothing is worn. Examples of Thermal Stress • Human deep-body temperature is maintained within a few degrees of 37°C (98.6°F). • Extreme variations from this deep-body temperature can adversely affect important chemical reactions and the structure and function of proteins. • The most common thermo-physiological threats to worker safety and productivity in industry are heat stress disorders. Of these, the most serious risk is heatstroke. • If heatstroke continues unchecked, it will result in blood clots, tissue death, cerebral (brain) damage, general central nervous system dysfunction, and finally death. • Death from heat strain (the body's response to heat stress) occurs when deep-body temperature approaches 43°C (109°F). • Hypothermia, or low deep-body temperature, can be dangerous. If the body temperature begins to drop, shivering starts at 34°C (93°F); • At 26.5°C (80°F) workers can become unresponsive, and death due to cold occurs rapidly at a rectal temperature of about 25°C (77°F)

2. Select a Heat Index

• A heat stress index should be selected that best represents the hot work in question • For most applications the WBGT is the preferred initial evaluation • Other indices that have been reported in the literature include: • Predicted 4-hr sweat rate • New effective temperature • Wet kata cooling power of air • Wet bulb-dry bulb index • Wet globe index • Temperature humidity index • Index of physiological effect • Index of thermal stress • Relative strain index • Reference index

Noise Dosimeter

• A special SLM that measures noise dose • Dose = % of allowable maximum sound level - 100% dose = 90 dBA for 8 hours • Different criteria can be selected - TLV (85 dBA) vs PEL (90 dBA) - 80 dBA threshold - Sampling time

Acceptable IAQ (20% people complain)

• ASHRAE* (American Society of Heating, Refrigerating, and Air Conditioning Engineers) "Air in which there is no known contaminants at harmful concentrations determined by cognizant authorities and with which a substantial (80% or more) of the people exposed do not express dissatisfaction."

10. Modify the Hot Work Exposure

• Acclimatization • Clothing • PPE • Fluid replacement • Training • Ventilation • Spot Cooling • Refrigeration • Fans • Radiant Shielding • Moisture Reduction • Isolation • Mechanization • Work scheduling • Providing Breaks • Buddy System

Biological Effects

• Acute somatic effects: - Immediate if acutely exposed. - Severity depends on dose. - Death due to bone marrow or intestinal wall injury. • Delayed somatic effects: - Cancer, leukemia, cataracts, organ failure, abortion. - Probability of an effects is proportional to dose. - Doubling risk of cancer: 10 - 100 rem. • Genetic effects: - Effects to off-spring of expo person irreversible. - Doubling dose for mutation: 50 - 80 rem.

Heat Stress

• Air conditioning (equipment cabs, break rooms) • Increase general ventilation • Local exhaust ventilation at areas of high heat • Cooling fans/misters • Reflective shields • Insulate hot surfaces • Eliminate steam leaks Cold Stress • Heated areas (equipment cabs, break rooms) • Minimize air • Portable heaters • Insulate cold surfaces • Eliminate leaks (e.g., cold liquids) PPE • PPE is available to help mitigate both heat and cold stress • Cooling vests • Hats, neck wraps • Reflective clothing • Insulating clothing • However, PPE may compound thermal problems for workers. • For example, welders may suffer from the heat in warm environments and from the cold in cool environments because their protective clothing retains heat in the summer, but the design of welding masks and gloves hampers adding adequate insulation in winter. • Chemical protective clothing can create a microenvironment under the clothing that may be uncomfortably hot during work, even when ambient temperatures are comfortable.

Volatile Organic Compounds (VOC)

• Aliphatic, aromatic & polycyclic hydrocarbons • Common analytes: • Aldehydes • BTEX • Methyl chloride • D-limonene • Pesticides • Phthalates • Acetone • Ethyl alcohol, etc • Sources: • Paints, lacquers, varnishes • Cleaning supplies, disinfectants • Pesticides • Building materials, furnishings • Copiers, printers • Glues/adhesives, permanent markers • Cosmetics • Air fresheners, etc.

Fungi/Mold

• Also ubiquitous. Viable versus nonviable. • Bad actors: • Histoplasma capsulatum, Aspergillus fumagatus & flavus, Coccidioides immitis, Cryptococcus neoformans. • Exposure conditions: • Is there a "reservoir" (organic matter + high RH)? • HVAC ducts, water damaged fabrics, wall board, carpets, humidifiers, etc • Is there aerosolization? • Is there an exposure path? • Most susceptible: immunocompromised.

IONIZING RADIATION

• Anticipation: - Characteristics of ionizing radiation - Hazards & risks - Industrial & environmental sources • Recognition: - Qualitative exposure assessment • Evaluation: - Quantitative exposure assessment • Control: - Radiation-specific controls

Work-Rest Intervals

• As heat strain increases, the ratio of work to rest must decrease • Safe scheduling of work and rest is not as simple as it might at first appear. • For example, in protective clothing in very hot environments (when rest must occur while wearing the clothing) it was better to have workers work continuously rather than work and rest, because they were unable to cool off during rest. • The balance between work and rest must consider both safety and thermal physiology, because workers resting in protective clothing may not cool much; however, doffing and donning protective clothing would increase worker risk of toxic chemical exposure. • Rest areas should be properly cooled/heated with access to water • Heated/cooled break rooms • Cooling tents with misters

Bacteria

• Bacteria are ubiquitous. Most are not pathogenic. • Bad actors: • Thermophilic actinomycetes, Legionella pneumophila, Mycobacterium tuberculosis, Pseudomonas aeruginosa. • Exposure conditions: • Is there standing water? • Cooling towers, evaporative condensers, pipelines, water heaters, holding tanks, humidifiers, etc. • Is there aerosolization? • Is there an exposure path? • Most susceptible: immuno-compromised.

Sound Level Meter (SLM)

• Basic instrument for measuring noise levels - Type 0 = laboratory standard - Type 1 = precision measurement in the field • Accuracy: ±1 dB - Type 2 = general purpose measurements • Accuracy: ±2 dB • Minimum requirement for OSHA • Most provide A and C weighting • Most have slow and fast response modes - OSHA requires use of the slow response - Some meters have an "impulse" or "peak" response

Heat Stress Index (HSI)

• Belding and Hatch developed the heat stress index (HSI) to express thermal stress of a hot climate as the ratio of the evaporative heat required (Ereq) to maintain the body in thermal equilibrium to the maximum evaporative capacity of the climate (Emax). HSI = Ereq/Emax × 100 • This index assumes individuals of average build (weight = 70 kg; height = 1.7 m; body surface area = 1.8 m2), dressed in shorts and gym shoes, with a skin temperature of 35ºC (95ºF), and uniformly wetted with sweat. • 36 or 37ºC are also sometimes used as an estimate of mean skin temperature for use in heat transfer equations.

Indoor Air Quality (IAQ)

• Building design, construction & maintenance; • Ventilation (HVAC) design, construction & maintenance; • Toxicology & occupational medicine; • Psychology; • Mycology, bacteriology, virology; • IH/OH assessment, characterization, evaluation, diagnosis, control, abatement, etc.

Carbon Dioxide (CO2)

• Byproduct of human metabolism/respiration. • Exhaled breath: 40,000 - 60,000 ppm • Atmospheric concentration: 398 ppm (+2 ppm/yr) Regulations/Guidelines: • ASHRAE: 15 cfm/person = [outside] + 615 ppm. • 15 cfm ≈ 3 air changes per hour (ACH). • NIOSH: 1,000 ppm = need for HVAC adjustment. • EU = 3,500 ppm. • OSHA PEL = 5,000 ppm as an 8-Hr TWA.

8. Evaluate Recommended Threshold Limits

• Calculate the RAL, REL and C for this work. • Is this worker at risk of heat illness when working at 30°C?

Laboratory-acquired Infections

• Chain of Infection - 1. Presence of pathogen in the laboratory - 2. Mode of transmission to the worker - 3. Portal of entry into the worker - 4. Worker must be susceptible to the pathogen Laboratory-acquired Infections • First recorded LAIs in the late 1800's - Typhoid (1885) - Cholera (1886) - Brucellosis (1887) - Tetanus (1893) - Cholera (1894) • > 5,500 reported cases (1930 - 2004) • 204 deaths • Known cause of infection in 16-18% of cases Laboratory-acquired Infections • Smallpox (1978) • Lab worker infected, spread to 2 family members • SARS-CoV (2004) • Lab worker infected, resulted in 9 cases • Pneumonic Tularemia (2004) • 3 lab workers at Boston University • Q-Fever (2006) • 3 lab workers infected at Texas A&M

Noise Controls

• Engineering - Acoustic materials - Noise blankets/barriers • Administrative - Hearing Conservation Program • PPE - Ear plugs/muffs

IAQ Controls

• Engineering • Building Design • Ventilation • Balance/Adjust HVAC System as needed • Temp/RH control • Administrative • Work practices (e.g., restrict indoor pesticide use) • Scheduling (e.g., cleaning, maintenance, renovations) • Good housekeeping • Communication • PPE?

Clothing

• Clothing insulating values are measured in clo units. • One clo equals the insulating value needed for someone to be comfortable sitting in a typical office environment of 21ºC (70ºF), 50% relative humidity, and air speed of 10 cm/s). • The clo needed is a function of the metabolic heat production. • Properly chosen clothing reduces or enhances conduction, convection, evaporation, and radiation in such a way that the metabolic heat production maintains core body temperature and skin temperature. • A strong draft (i.e., convective heat loss) alters the clo level needed for comfort, as does an increase in metabolic rate. Insulation of clothing required at different metabolic rates to maintain thermal comfort at different air temperatures. One (1.0) MET equals the resting metabolic rate of approximately 100 W (3.6 mL/kg of body weight/min of oxygen consumption, or an average of 200-250 mL/min).

Clothing

• Clothing insulating values are measured in clo units. • One clo equals the insulating value needed for someone to be comfortable sitting in a typical office environment of 21ºC (70ºF), 50% relative humidity, and air speed of 10 cm/s). • The clo needed is a function of the metabolic heat production. • Properly chosen clothing reduces or enhances conduction, convection, evaporation, and radiation in such a way that the metabolic heat production maintains deep-body temperature and skin temperature. • A strong draft (i.e., convective heat loss) alters the clo level needed for comfort, as does an increase in metabolic rate. Insulation of clothing required at different metabolic rates to maintain thermal comfort at different air temperatures. One (1.0) MET equals the resting metabolic rate of approximately 100 W (3.6 mL/kg of body weight/min of oxygen consumption, or an average of 200-250 mL/min).

IAQ Summary

• Complex occupational health challenge. • Requires a team-based approach, especially for BRI. • Ensure you know the nature of the IAQ problem(s). • Need to know building, HVAC terminology, design and maintenance practices. • Follow an investigation process, be thorough. • Exercise caution in allowing the "issue owner" to dictate the course & nature of the investigation. • The goal is improved IAQ, not collection of data. • Improved IAQ is both subjective & objective. • Risk communication is an important skill.

Hearing Loss

• Conductive • Sensorineural - Noise Induced Temporary Threshold Shift - Noise Induced Permanent Threshold Shift - Tinnitus • Acoustic Trauma (explosion) - Can be conductive and/or Sensorineural

Alpha () Particles/Radiation

• Consists of helium nucleus (2 protons & 2 neutrons). • Generated from the nucleus. +2 charge. • Heavy (4 atomic mass units). • Typical energy: 4 - 8 MeV. • Limited range: <10 cm (air); 60 m (skin). • Easily shielded (paper, skin, etc.) internal hazard. • Isotopes with very heavy, unstable nuclei decay via alpha radiation, e.g., uranium, radium, etc. • High Linear Energy Transfer (LET) energy (QF=20).

Gamma () & X-Rays

• Consists of photons ejected from nucleus. • Often found with and emissions (decay). • No charge or mass. • Typical energy: in MeV range, but unlimited. • Range: unlimited at the speed of light (C). • Dermal burn hazard. • Very penetrating, but light damage (QF=1). • Shielded with earth, concrete, lead. • Emitters: Potassium-40, Iodine-131, Cobalt-60.

Temperature & Relative Humidity

• Critical parameters for acceptable IAQ • ASHRAE Standard 55-1992: Thermal Environmental Conditions for Human Occupancy • Regardless of ASHRAE settings, individual tastes and susceptibilities can make acceptable thermal comfort difficult

Fungi

• Different from plants in that they do not make their own food (i.e., no photosynthesis) • Includes mushrooms, molds and yeasts • Get nutrition by breaking down dead plants or decaying human tissue • Non-toxic varieties may be useful in industrial processes (e.g., production of alcohol, enzymes, cheese) Fungi • Examples - Aspergillus fumigatus and A. flavus • Opportunistic human pathogens • Causes Aspergillosis in immuno-compromised patients - Histoplasma capsulatum • Causes histoplasmosis • Typically from exposure to bird or bat droppings

Characteristics of Sound

• Displacement of molecules (sound) propagates as a wave. We can identify and measure characteristics of this wave. c = λf c = speed (speed of sound in air = 344 m/s) λ(lambda) = wavelength (meters), f = frequency (cycles per second, Hz) • Amplitude is height of wave

Non-Ionizing Radiation PPE

• E-field: basic clothing, gloves with block • M-field: more transparent, clothing won't block • Sunscreen • Respiratory protection is unnecessary

EMF Hazards

• EMF can cause biological effects in humans, but the evidence of health effect is limited. • At low frequencies, external electric and magnetic fields induce small circulating currents within the body. The levels of induced currents inside the body are too small to produce obvious effects. • The main effect of radiofrequency electromagnetic fields is heating of body tissues. • Despite extensive research, to date there is no evidence to conclude that exposure to low level electromagnetic fields is harmful to human health. • The focus of international research is the investigation of possible links between cancer and electromagnetic fields, at power line and radiofrequencies.

EMF Measures

• Electric field strength (V/m) • Magnetic field strength (A/m) • Power density: watts per square meter (W/m2): - Cross product of electric and magnetic fields. - Increasing field strength increased power density. • Specific absorption rate (SAR): - Energy absorption in tissue. Measured in W/kg • Specific absorption (SA): - Absorption rate, time dependent.

Hearing Conservation Program (HCP)

• Employers shall administer a Hearing Conservation Program when employee(s) is at or above an 8-hour TWA 85 dBA. - In keeping with many OSHA regs, this is an AL of 50% of the PEL • Minimally, a HCP must include: - Monitoring, feasible engineering or admin controls, audiometric testing, hearing protection, education & training. Hearing Conservation Program (HCP) • Monitoring - Sound levels from 80 to 130 dBA integrated into noise measurements • Feasible Controls - Engineering controls, administrative controls. PPE in the interim while above are sought. • Audiometric Testing - Performed by licensed/certified Audiologist - No cost to employee - Baseline within 6 months of first exposure at AL - Annual testing thereafter Hearing Conservation Program (HCP) • Training & Education - Performed annually and includes effects of noise on hearing, proper use of PPE, audiometric testing and interpreting results. • Record Keeping - Legal requirements to maintain records for duration of employment. - Realistically maintain records for lifetime of employee (for legal ramifications).

Engineering Controls

• Engineering controls can be employed to improve safety and productivity in hot and cold environments. • For example, reducing the heat loss from kilns by improving seals and insulation saves energy and lowers the heat strain in the surrounding areas. • Installing radiant heat shields may be very cost-effective in many situations because of the resulting increase in worker productivity. • Job redesign may be necessary to lower worker metabolic rates (i.e., lower metabolic heat production) to reduce heat strain, which can increase productivity.

Rickettsia

• Eubacteria • Very small gram negative intracellular parasite • Non-motile • Non-spore forming • Non-encapsulated • Live in the cells of ticks and mites Rickettsia • Examples - Rickettsia rickettsii • Causes Rocky Mountain Spotted Fever • Transmitted by ticks - Rickettsia australis • Causes Queensland Tick Typhus • Transmitted by ticks

Quantitative Exposure Assessment

• Exposure assessment: - What's the purpose? Characterize exposures? Assess controls? Incident investigation? - Immediate/short-term/continuous - Direct read vs integrated air sampling - Area vs personal. - Whole body vs body part(s). • Compare resulting data to what standard(s) - Are they significant, legal, representative? • What action should be taken?: - Controls? Biological monitoring? Education? Notification? etc.

Activity-Based Risk Assessment

• Fort Detrick 1950's • Infectious agents dispersed during: - Blending - Pipetting - Removal of stoppers and cotton plugs from culture tubes - Removal of hypodermic needles from vaccine bottles - Pouring and streaking of plates - Transferring with inoculating loops - Inoculating animals - Macerating tissues & harvesting fluids "Practically every manipulation in the microbiological laboratory creates aerosols, and these aerosols are probably the source of many laboratory infections" Reitman & Wedum 1956

Definitions

• Frequency: related to pitch of the sound. - Audible range for humans with good hearing is between 20 Hz and 20,000 Hz. - High frequency noise generally more annoying than low frequency noise - Pure tones (narrow frequency bands) more harmful than broadband (many frequencies) noise. - Hz = cycles/second • Intensity (amplitude) is related to the loudness of the sound. • Wavelength is the distance the sound wave travels in one cycle (distance between two analogous points on two successive parts of a wave). • Wavelength is an important property of sound. - Sound waves with wavelengths much larger than an obstacle are hardly effected by that obstacle - Sounds with small wavelengths in comparison to size of an obstacle will reflect and scatter the wave in many directions c = λf c = 344 m/s

Frostbite

• Frostbite is more common than hypothermia. • It is a result of freezing the extra cellular fluid in the skin, which can permanently damage the tissue. • Though not life threatening, frostbite damage can be severe and permanent, so prompt medical attention is required. • It usually occurs on the extremities, such as the tips of the fingers, ears, and nose, and manifests itself with initial pain at the afflicted site, which subsides as nerves are damaged. The tissue becomes white or grayish. • Because the face is often less protected than other body parts, the victim may be unaware of the first signs of frostbite on the nose and ears because they cannot see the discoloration. • Problems can arise before serious cold injury occurs. • Rapid heat transfer by conduction can occur if a body part comes in contact with a very cold object, even if the ambient air temperature is mild. • Workers should be trained to avoid direct contact with cold metal (<0°C) or with liquids of low vapor pressure such as alcohol or cleaning fluids, all of which can increase the possibility of frostbite. • Workers exposed to extreme cold or moderate cold with high wind (>10 m/s), are in danger of frostbite and hypothermia. • Frostbite can occur even in warmer temperatures if workers are not properly clothed. • Cold exposure can reduce dexterity and strength. • Even if the deep-body temperature is normal, dexterity begins to decline when hand skin temperature falls to 15 - 20°C, which is a very common temperature for work in cold environments.

Ozone

• Generated by O2 in the presence of a corona discharge (e.g., ionization or high voltage source) • Ionic air purifier • Laser printers • Arc welding • Component of ambient photochemical smog • Primary pulmonary irritant • OSHA PEL: 0.1 ppm 8-hr TWA • ACGIH TLV: 0.05 ppm (heavy work), 0.08 ppm (moderate work), 0.1 ppm (light work); 0.2 ppm (exposures ≤2hr)

Agent-based Risk Assessment

• Hazardous Characteristics of an Agent - Pathogenicity (ability to cause disease) - Virulence (severity of disease)

Mechanisms of Thermal Exchange

• Heat Production -> From muscles • Evaporation -> Dissipates heat through sweat • Convection -> From (1) blood circulation inside the body and (2) movement of air/water across the skin • Conduction -> heat transfer by direct contact Radiation -> electromagnetic transfer of heat without direct contact

Beta () Particles/Radiation

• High speed electron ejected from the nucleus. • Can be either positive or negatively charged: - Negative = electron (-); Positive = positron (+) • Much lighter than -- 0.0005 AMUs. • Typical energy: low KeV - 5 MeV. • Range: 12'/MeV (air); low mm (tissue). • Low LET (QF = 1). • High MeV beta affects skin; watch the eyes! • 1 an internal (inhalation/ingestion) hazard. • Shielded by clothing, eyeglasses, thin aluminum. • emitters: - Tritium, Carbon-14, Strontium-90, Phosphorous-32,

Laboratory Procedure Risks

• High-energy operations - Blending, mixing with pipette, dropping samples, sonicating • 1.0 - 7.5 µm • Surface contamination - Vortex mixing by hand, opening containers, pipetting, pouring, spills, shaking • Large droplet contamination

UV Radiation

• Highest photon energy range. • Limited penetration. Target organ: skin, cornea. • Three ranges: - UVA (Near): May affect lenses. - UVB (Actinic): Most hazardous. - UVC (Far): High photon energy; absorbed by atmosphere • ACGIH TLV @ 270 nm limits: 1 mW/cm2 - Protection against sunburn, conjunctivitis, skin cancer. • UV hazardous because of the delay effects.

thermal stress

• Hot and cold environments are thermal stressors that can cause physiological stress and may reduce both safety and productivity • Besides the obvious dangers from frostbite or heatstroke, even a milder thermal strain can be problematic. • Environments do not have to be life threatening to cause problems.

3. Select Instruments

• WBGT can be calculated by measuring: • Globe temperature • Air temperature (dry bulb) • Natural wet bulb temperature • Or measured directly with an appropriate instrument

Building-Related Illness

• Hypersensitivity diseases: • IgE-mediated (asthma, allergic rhinitis, etc.). Objective symptoms. • Hypersensitivity pneumonitis: • IgG and cellular immune-mediated. Objective symptoms. • Infection: • Influenza (H1N1, H1N5, etc), cold, tuberculosis, Legionnaire's disease, Pontiac fever. • Chemical: • Acute or chronic (organ-specific or systemic) conditions associated with exposure to IAQ pollutants (CO, NOx, VOCs, etc). Normally objective symptoms.

Hypothermia

• Hypothermia is the most dangerous cold threat, but fortunately it is rare in industry. • Extremely low temperatures can interfere with vital biochemical processes. Symptoms include: • Uncontrollable shivering • Intense feelings of cold • Falling blood pressure • Irregular heartbeat • Incoherent/disoriented behavior • Drowsiness • Once hypothermia begins, the blood vessels near the skin may dilate, causing further heat loss, which may result in further reduction in deep-body temperature and cause death even after a person is moved to a warmer environment. • The best data suggest that humans with deep-body temperatures <25°C will die.

Characteristics of Heat Acclimatization

• Increase in the amount of sweat à increases evaporative cooling potential • Earlier onset of sweating à reduces heat storage prior to activation of evaporative cooling • More dilute sweat (lower salt concentration) à reduces electrolyte (chiefly sodium and chloride) losses • Increased skin blood flow à provides greater convective heat transfer between deep body and skin • Reduction in heart rate at any given work rate à lowers cardiovascular strain and the oxygen requirements of the heart • Greater use of fat as fuel during heavy work à conserves carbohydrates that are useful when very high rates of energy production are needed • Reduction in skin and deep-body temperature at any given work rate à maintains a larger heat storage reserve and permits the worker to work at a higher rate

Airborne Particles

• Inhalable versus respirable • Organic versus inorganic • Environmental tobacco smoke • Sources: • Printing • Paper handling • Smoking & other combustion • Outdoor sources (e.g., pollen) • Deterioration of materials • Construction/renovation • Vacuuming, sweeping • Insulation • Human/animal dander

4. Measure the Thermal Environment

• Instruments should be placed in actual working locations • Allow stabilization to the environment • Dry bulb and wet bulb thermometers should be shielded from sun/radiant sources • Wicks on the wet bulb should be clean and fully wetted • Repeated readings may be useful if conditions change • Determine temperature and amount of time at each location

EM Spectrum Expressed

• Ionizing radiations (expressed in photon energy): - X-ray >100 eV (typical) - Gamma rays >100 KeV (typical) • "Optical" radiations (expressed in wavelength): - Ultraviolet (UV) 0.4 m - 0.1 m - Visible 0.7 m - 0.4 m - Infrared (IR) 300 m - 0.7 m • Radiofrequency radiations (expressed in frequency): - Microwave (MW) 300 MHz - 300 GHz - Radiofrequency (RF) 300 Hz - 300 MHz - Extremely low frequency (ELF) 30 Hz - 300 Hz

Recognition

• It is difficult to evaluate problems when workers are entirely clad in coveralls, respiratory protective masks, and other equipment . • EXAMPLE: for workers in hazardous environments, the need for respirators and decontamination before drinking fluids may greatly hamper adequate hydration. • Self-monitoring is often difficult. • Therefore, it is imperative that both workers and work site supervisors appreciate the importance of the symptoms the worker may display. • Workers should be paired with others for work in hot or cold environments, with instructions to watch for signs of thermal strain in each other. • It is also important for workers and supervisors to realize that there is tremendous variability among workers in thermal tolerance • What one worker may find merely uncomfortable could result in a dangerous level of heat strain for other workers doing the same work in the same environment. • Often it is the most industrious "get-the-job-done" employees who place themselves at greatest risk for heat or cold injury. Recognition The first and simplest step in assessing the thermal environment is to recognize that many jobs are inherently thermally stressful: o Fire fighting o Smelting o Boiler cleaning or maintenance o Plastics extrusion or molding o Asphalt paving or roofing in the summer, among others. Very low temperature jobs include: o Emergency work in inclement weather (including unseasonable but otherwise mildly cool weather) o Any task where workers may become wet in cold environments

9. Determine Thermal Components

• Knowledge of specific thermal components can provide assistance with controlling heat. • High globe temperatures -> radiant shielding • Low air velocity -> increased ventilation • High natural wet bulb temperature -> moisture control

Biohazard Exposure

• Laboratories • Biotechnology • Healthcare • Emergency responders • Agriculture • Veterinary science • Food handling

Heat Exhaustion and Heat Cramps

• Less dangerous but more common than heatstroke • Not necessarily life-threatening, but may be first sign of impending heat stroke • Workers who experience undue fatigue or muscle cramps while working in the heat may be suffering from heat exhaustion and should be required to sit or lie down in a cooler environment • If heat cramps persist, an intravenous infusion will be required • Often people will have a headache and may feel nauseous. • Their skin is usually pale, and they may feel faint. • Because it may be difficult to distinguish between heat exhaustion and heat stroke, it is wise to observe all heat exhaustion cases very closely. • If sweating stops suddenly, or the worker loses consciousness or becomes disoriented, they should be treated as having heat stroke, and medical help should be summoned immediately.

Cold Exposure Limits

• Limits for exposure to cold environments are difficult to specify because the amount of clothing and its insulating characteristics have such a dominant effect on the extent of cold exposure. • A sleeping bag can provide enough insulation to withstand extreme cold conditions, even though the contribution of metabolic heat is low. • The effects of exposure to cold environments also vary dramatically based on the amount of metabolic heat being generated by any work being performed. • Workers can go through zones of comfort, heat stress, and cold stress with the same clothing and thermal exposure. • For example, a worker dressed in heavy clothing may be comfortable at light work, sweating inside these clothes during heavy work periods, then very cold during a subsequent rest break with the damp clothing and low metabolic heat.

Administrative Controls

• Warning signage • Designated areas • Training & education • Policy & procedures • Job safety analysis • Work permit system • Job rotation

ELF Radiation

• Main focus: power frequency at 60 Hz (US) - Magnetic field is primary concern. • Body absorbs little energy at these frequencies. • Concern: childhood leukemia near power lines - 5 - 10 mG (1/1000 TLV). • ACGIH TLV: 1 mT or 10 G from 60 Hz. • Measured using a frequency-specific meter - Looks at magnetic field.

Other Factors: Medications

• Many therapeutic and social drugs as well as alcohol can have an impact on a worker's tolerance for thermal stress • For example, excessive alcohol use can leave someone chronically dehydrated • Nearly any drug that affects central nervous system activity, cardiovascular reserve or body hydration could potentially affect thermal stress tolerance • Beta-blockers (for controlling heart-rate) can compromise work ability in jobs with high heat stress • Vasoactive (affecting blood vessel size) drugs can influence heat loss and blood supply, increasing susceptibility to hypothermia and frostbite • The Physician's Desk Reference Guide to Drug Interactions, Side Effects and Indications lists medications that may affect heat tolerance or hydration levels in some manner. • Any worker who is taking any medication should receive medical clearance before being exposed to hot or cold conditions.

Job Rotation

• May be included as part of a work-rest cycle For example, rotating between an activity with high metabolic activity (e.g., active movement) and one with low metabolic activity (e.g., sitting)

Dosimeters

• Measure accumulated dose. • New instruments measure dose rate. Film badges, Thermoluminescence detectors (TLD), pocket dosimeters

Evaluation: Core Body Temperature

• Methods for estimation of core body temperature include: • Rectal • Gastrointestinal • Aural • Oral -temporal

Viruses

• Microscopic pathogenic infectious agents • Multiply in connection with living cells • Found in all living things (incl., bacteria, fungi) • Varying morphologies - Spirals, 20-sided figures, etc. • Mostly genetic material (DNA, RNA) - May be single or double stranded • Not considered "cells" - Cannot carry out life functions independently Viruses • Examples - Common cold - Influenza - Viral Hepatitis A, B, C, D, and E - Herpes - Polio - Rabies - HIV

Scheduling

• Most industries do not have a great degree of scheduling flexibility, but annual planning and careful scheduling to minimize stressful exposure to heat or cold when possible can improve safety and increase productivity. • Factors to be considered in scheduling include time of day, season, and location. • When possible, work in very hot outdoor environments should be scheduled for night or for early/late in the day. • Outside work requiring protective clothing should, when practical, be scheduled for the coolest months.

Neutron () Particles/Radiation

• Neutron ejected from a nucleus (nuclear fission). • Not part of natural radioactive decay. • 1 AMU with neutral charge. • Neutrons are unstable and decay by emission. • Readily absorbed by nuclei of other atoms. • Range & LET dependent on speed. • 3 types: - Slow neutrons (<10 KeV; QF=1) - Thermal neutrons (QF=3) - Fast neutrons (>10 KeV; QF=10) • activation: ability to initiate radioactivity in other substances, including human tissue.

Exposure Standards & Guidelines

• No OSHA or MSHA standards, e.g., PEL, STEL, but: - Welding goggles expected to be protective for EMF. • NIOSH: "NIOSH and other government agencies do not consider EMFs a proven health hazard." • ACGIH: don't exceed Electric: 25 kV/m (0-100Hz) Magnetic: 10 G Workers with pacemakers E= 1kV/m M=1G ICNRP see notes

HPD & Noise Reduction Rating

• Noise Reduction Rating (NRR) Lp = Lm - (NRR - 7) dBA Lp = Protected Sound Level Lm = Measured Sound Level NRR = mfg published noise reduction value • NRR is based on testing under IDEAL, LABORATORY conditions (perfect fit, favorable frequency etc.,). • NOISH reduction factors: - Muffs 75% - Formable 50% - Pre-molded/other 30%

Non-Ionizing Radiation

• Non-ionizing radiation has less energy than ionizing radiation, but can cause changes in vibrational and rotational energies of molecules of tissue, usually dissipated in the form of energy. • Does not cause structural changes to atoms • Includes electric & magnetic fields (EMF) which are created whenever electricity is generated or used. • Produced by power lines, electric wiring, electric equipment and appliances. • Risk is focused primarily on magnetic fields. • The most common frequency for EMF is 60 Hz, the North American power standard.

Guidance Documents

• OSHA has also published fact sheets on both heat stress and cold stress • "Water. Rest. Shade" Campaign: https://www.osha.gov/heat/index.html • Heat Safety Tool app • OSHA, DOL, CDC, NIOSH collaboration • The most recent NIOSH document on heat stress is Criteria for a Recommended Standard - Occupational Exposure to Hot Environments, Revised Criteria 1986, Publication No. 86-113, 1986. • The ACGIH document on cold stress is Cold Weather Workers Safety Guide, Publication 9758 (1995). • Their recommended exposure guidelines appear in the TLV booklet (more on those later....)

Standards

• OSHA has published no regulations specifically for protection of workers from heat stress or cold stress. • However, the General Duty Clause would apply • The U.S. Department of Health and Human Services, NIOSH and OSHA have issued advisory documents on heat stress, and the ACGIH has published an advisory document on cold stress. • These advisory documents are consistent with standards on the subject published by International Organization for Standardization (ISO). • The ISO documents are widely referenced and used; they are legally binding only if they are included in state or local laws, labor contracts, or other agreements.

1. Preliminary Review

• Observe work site: • Type of work • Thermal characteristics • Type of clothing • Other relevant job/worker characteristics • Review records of previous heat-related injuries/illnesses

Heat Acclimatization

• Occurs very rapidly, with substantial adaptation apparent after only 2 hours of heat exposure per day for 8 consecutive days. Additional acclimatization continues to occur with additional exposure. • Despite a high degree of acclimatization, when environmental conditions are extreme, productivity will inevitably fall, and this reduced productivity should be anticipated. • If workers must wear impermeable encapsulating chemical protective clothing, some of the value of acclimatization may be reduced. • However, it most likely enhances work tolerance and reduces cardiovascular strain from heat exposure while in protective clothing.

Bacteria

• Oldest and most abundant life on Earth • Found almost everywhere • One cell microbes that grow by simple division • Unlike animal and plant cells, bacterial cells lack a nucleus • 3 morphologies: - Spherical (cocci) - Rod-shaped (bacilli) - Spiral (spirilla) • Relatively few bacteria cause infectious disease in humans Bacteria • Examples - Escherichia coli • E. coli O157:H7 or "flesh-eating" bacteria • Found with fecal matter contamination - Mycobaterium tuberculosis • Historically very significant in US • Spread by coughing/sneezing

hvac components:

• Outside air intake • Dampers • Mixing chamber/plenum • Filtration • Heat & cooling exchanger • Ducting • Supply register/diffusers • Exhaust register/grilles • Fan unit(s) • Thermostat & other controls

OSHA noise

• PEL: 90 dBA • AL: 85 dBA • Exchange Rate: 5 dBA exceeding the AL requires implementation of a Hearing Conservation Program

Prions

• PROteinaceous INfectious particles • Lack nucleic acids • Composed of abnormal variant of normal cellular protein Prions • Examples - Bovine spongiform encephalopathy • "Mad Cow Disease" • Only affects cows - Creutzfeldt-Jakob disease • Human form of Mad-Cow Disease • Fatal degenerative brain disease

Microwave & RF Radiation

• Penetrate deeper than optical radiation. • Can affect internal organs at "thermal intensities:" - Heat stress, increase heart rate, ocular changes, etc • General symptoms not recognized in the US - Depression, headache, irritability, memory loss, etc. • OSHA standard: 10 mW/cm2 averaged over 6 min. - Protects against thermal load. • MW measured using dipole antenna (E field) & loop antenna for magnetic field. • RF measured using both fields since exposures can occur within a few wavelengths.

Carbon Monoxide

• Product of incomplete carbon combustion • Multiple indoor & outdoor sources: • Idling vehicles near intake • Heaters/furnaces • Heavy equipment, etc. • Smokers more susceptible. • Chemical asphyxiant (carboxyhemoglobin) • Causes front-lobe headache, dizziness, confusion, nausea • Odorless, colorless - if uncertain, don't assume! • OSHA PEL: 35 ppm 8-Hr TWA.

Anticipation

• Protecting against thermal strain disorders is primarily a matter of anticipating problems and trying to prevent even mild disorders from developing. • Most important defensive measures: • Gradually acclimatizing workers, • Keeping them well-hydrated • Detecting symptoms early • Workers showing initial signs of any heat or cold disorder should be removed from exposure and given fluids for rehydration. • The use of encapsulating protective clothing may hamper both the worker's temperature control AND rehydration.

Radon

• Radioactive decay of Uranium-238 to Radon-222. • Radon is an inert gas - but produces particles. • Risk comes when particles attach to dust and get inhaled • Evaluate with charcoal canister • Controlled with ventilation, typically under the foundation/basement • EPA guideline for inhabited buildings: 4.0 Pci/L

Radon

• Radioactive decay of Uranium-238. • Inert gas. • Evaluate with charcoal canister - basement? • EPA guideline for inhabited buildings: 4.0 Pci/L

Sound Pressure

• Relative scale vs. absolute scale • Decibel: 1/10th of a bel and is the minimum difference in loudness that is perceptible. • Bel: used to compare 2 power levels, equal to the log to the base 10 of the ratio of the 2 powers. • SPL = Lp = 20log(Pm/Pref) SPL: sound pressure level = Lp Pm: measured Pressure Pref: reference Pressure

Exposure & Dose Terms

• Roentgen (R): ionization in air due to X or . • Rad (radiation absorbed dose): energy absorbed from radiation in any material. • 1 rad = 100 ergs/gm = 10-2 Joule/kg. • Rem (Roentgen equivalent man) (Not: "radiation exposed man"): relates effectiveness of different radiations in producing biological damage, to the quantity of radiation (dose equivalent). • Dose equivalent (rem) = rad X QF • Sievert: SI unit for dose equivalent (1 Sv = 100 rem) • Gray: SI unit for absorbed dose (1 Gy = 100 rad)

Controlling Cold Stress

• Several steps that can be taken for minimizing thermal stress in cold environments include: • Reducing air velocity and minimizing drafts • Placing windbreaks as needed • Balancing work rate so that periods of intense work are not followed by low work rates • Increasing the clothing insulation • Using windproof clothing as appropriate • Providing capability to dry clothing that is wet or damp • Increasing radiant heat with micro- or spot heaters

Controlling Heat Stress

• Several steps that can be taken to minimize thermal stress in hot environments include: • Macro cooling (i.e., cooling the general work environment) • Reducing ambient humidity and/or increasing air velocity • Lowering metabolic rate by implementation of slower work rate or provision of mechanical assistance • Adjusting clothing or adding micro-environmental cooling • Providing radiant shielding • Providing a cool location, or spot cooling, for rest breaks • Providing plenty of palatable fluids of the workers' preference for rehydration

Hearing Protection Devices (HPD)

• Several types of HPD available - Premolded - Formable - Semi-insert - Earmuffs - Helmet

Half-Value Layer (HVL)

• Shield thickness needed to reduce intensity by 50%. • Measured by: HVL = 0.693/ • = Linear absorption coefficient: fraction of a beam of x-rays or gamma rays absorbed or scattered per unit thickness of the absorber.

Controls

• Shielding to reflect radiation. • Shielding to absorb radiation. • Restrict access to radiation. • Increase distance from the source. • Limit time of exposure. • Substitute for less hazardous radiation.

Parasites

• Single or multicellular organisms • Live on or in a host, where they get nutrients but provide no benefit • Assumed to be detrimental Parasites • Examples - Toxoplasma gondii • Causes toxoplasmosis • Spread from contaminated cat feces • Fatal infection/death possible • Pregnant women especially at risk - Trichinella spiralis • Intestinal roundworm that causes Trichinellosis • Spread by poorly cooked foods (especially, pork)

Sound vs. Noise

• Sound: any pressure variation in air, water or other medium that the human ear can detect. • Noise: sound that bears no information and whose intensity usually varies randomly in time. - Sound that is unwanted by the listener. - Interferes with perception of wanted sound. - Likely to be harmful.

Filter or Weighting

• Sounds have components at many frequencies • A-weighted response (dBA) simulates sensitivity at moderate sound levels - weight of low freq sounds reduced and high freq sounds slightly increased - After weighting, levels summed logarithmically to give A-weighted sound level • C-weighted response simulates sensitivity of human ear at high sound levels. • Modern noise dosimeters make these weightings (calculations) internally • Octave band Analyzer measures sound levels at a range of frequencies. Useful for choosing control or PPE.

Heat Rash

• Sweat glands can become clogged and often become infected, causing discomfort that may reduce worker productivity. • If large areas of skin become affected, sweat production can be compromised, reducing heat tolerance.

Other Heat-Related Problems

• Sweat in the eyes à can become a safety hazard • Dripping sweat à can damage sensitive equipment or be an electrical hazard • In impermeable clothing, quantities of sweat can collect in boots and gloves. • Heat stress can also reduce concentration and lead to early fatigue in workers. • Any worker who has experienced a previous heat injury is more susceptible to a subsequent injury and should be afforded more protection (e.g., reduced exposure time, more rest periods, etc.)

Effect of Electrolytes

• Sweat is a mixture of water, electrolytes, and lactic acid. Electrolytes essentially are minerals (e.g., sodium, chlorine, potassium, calcium) which are vital to the normal functioning of the body. • Sweat of acclimatized workers contains 1-4 g/L of electrolytes, and the sweat of unacclimatized workers contains even more. • The losses of sodium and calcium resulting from 6 hours of work can exceed the normal daily intake. • This suggests that workers exposed to repeated days of profuse sweating may incur electrolyte deficits that can pose a health risk. • It has been argued that rehydration is not complete until all the electrolytes lost in sweat are restored such that all the body fluid compartments are returned to preexposure status. • The thirst drive may be reduced too quickly by drinking low-concentrate drinks, which his why it is often recommended that the drinks be high in electrolytes.

ACGIH NOISE

• TLV-TWA: 85 dB • Exchange Rate: 3 dB Ceiling: 140 dB

WBGT Comparison to OELs

• Table 24.9 summarizes and compares several of the proposed WBGT threshold limits where workload levels have been specified. When the different metabolic heat assumptions are considered and threshold limit proposals are compared, a pattern of consistency is observed: • resting 32-33 ºC • light 30 ºC • moderate 27-28 ºC • heavy 25-26 ºC • very heavy 23-25 ºC • Given the imprecision associated with estimating metabolic workload and the variability of metabolic costs during the day and from day to day, the WBGT threshold values in Table 24.9 are all basically equivalent.

Worker Training

• Teaching workers to recognize potential hot/cold problems and training them to deal with these should improve both safety and productivity. • For example, training workers to maintain good levels of hydration and to select protective clothing that provides the maximum protection with the minimum heat strain • If workers select impermeable protective coveralls when only a regular (uncoated) fabric is needed, the heat strain is much higher than necessary, and worker productivity and safety are reduced. • Workers and supervisors should be taught that therapeutic and recreational drugs may alter hot/cold tolerance, and that workers who report a fever should be protected from heat exposure.

WBGT

• The WBGT (Wet Bulb Globe Temperature) was originally developed for use in controlling heat casualties at military training centers. • The WBGT combines the effect of the four main thermal components affecting heat stress: air temperature, humidity, air velocity, and radiation, as measured by the dry bulb (Tdb), natural wet bulb (Tnwb), and globe (Tg) temperatures. • For indoor conditions (or outdoors without solar load, e.g., cloudy or shaded), WBGT values can be determined from the following equation: WBGT = 0.7 Tnwb + 0.3 Tg • For conditions with solar radiation, the equation becomes: WBGT = 0.7 Tnwb + 0.2 Tg + 0.1 Tdb WBGT • Different forms of these equations have been proposed to define WBGT estimates under different conditions, but these two are the most widely used and accepted. • In 1969 a panel of international experts from the World Health Organization (WHO) reviewed several thermal indices including CET and HSI. • The panel determined that none of the indices specifically predicted the physiological strain to be expected from exposure to heat. • NIOSH later established five principal criteria for a standard heat stress index for industrial use. • Based on these criteria it recommended the WBGT index as the standard heat stress index. The Occupational Safety and Health Administration (OSHA) Advisory Committee, ACGIH, and ISO also recommend the WBGT as the primary heat stress index. WBGT • NIOSH (1972) suggested the use of a tripod with thermometers measuring air, natural wet bulb, and globe temperature as the standard means for determining the WBGT. • Integrated electronic instruments for measuring WBGT, are available commercially. • Such instruments provide a direct or digital readout of WBGT and, in some models, air velocity, dry bulb, wet bulb, and globe temperatures as well. • The stabilization time required for the WBGT standard tree is at least 20 min, due to the large globe thermometer (15 cm in diameter) • The stabilization time required for the integrated electronic instruments is usually about 5 min, because all the sensors are resistance thermometers, and the globe has a small diameter (~4 cm)

Thermal Measurements

• The dry bulb temperature (Tdb) is measured with a thermometer (e.g., a liquid-inglass thermometer). Temperature units are expressed in degrees Celsius (ºC), Kelvin (K) (), or degrees Fahrenheit (ºF) (F=9/5 Celsius+32). • The term air temperature is synonymous with dry bulb temperature. • Celsius (or centigrade) and Kelvin units are SI units. K = ºC + 273 ºF = 9/5(ºC) + 32 • The psychrometric wet bulb temperature, commonly called wet bulb temperature, is measured by a thermometer on which the sensor is covered by a wetted cotton wick that is exposed to forced movement of the air. • Accuracy of wet bulb temperature measurements requires using a clean wick, distilled water, and proper shielding to prevent radiant heat gain. • The natural wet bulb temperature (Tnwb) is the temperature measured when the wetted wick covering the sensor is exposed only to naturally occurring air movements. • The globe temperature (Tg) is a measure of radiant heat. It is obtained by placing the sensor of a thermometer in the center of a hollow copper sphere, usually 15 cm in diameter and painted a matte black to absorb the incident infrared radiation. Globe temperature also can be obtained from electronic instruments that use black spheres with diameters ~4 cm. • The relative humidity is the ratio of the actual amount of moisture in the air to the amount of moisture that the air could hold if saturated at the same temperature. The percentage value of this ratio is usually used to describe relative humidity. • The vapor pressure is the pressure at which a vapor can accumulate above its liquid, if the vapor is confined over its liquid and the temperature is held constant. Normal units for vapor pressure are mmHg, torr, or kPa, where 1 mm Hg=1 torr, and 7.5 torr=1 kPa. • The dew point temperature is the temperature at which condensation of water vapor in a space begins, for a given state of humidity and pressure, as the vapor temperature is reduced. • There is a unique dew point temperature associated with each combination of dry and wet bulb temperatures. • The velocity of the air movement is also called wind speed. SI units for air velocity are meters per second (m/s). • Feet per min (ft/min) is often used for ventilation • Miles per hour (mph) or kilometers per hour (km/hr) is often used in meteorology • The mean radiant temperature is the temperature of an imaginary black enclosure, of uniform wall temperature, that provides the same radiant heat loss or gain as the environment measured. It can be approximated from readings of globe temperature, dry bulb temperature, and air velocity. • A comprehensive discussion of the instruments and methods for measuring the components of thermal environments can be found in ISO 7726.

Other Factors: Physical Fitness

• The greater the physical fitness level of the worker, the more the worker will adapt to and/or tolerate thermal stresses • Physical fitness leads to better thermal tolerance primarily because fitness leads to increased blood volume and improved cardiovascular capabilities • Aerobic fitness is known to increase blood volume, cardiac stroke volume, maximal cardiac output, and capillarization of the muscles. • These changes lower the cardiovascular strain for any given work rate, as well as increase the physiological reserves. • For example, the increased blood volume becomes important when blood must simultaneously supply the muscles with oxygen at the same time it must transport heat to the skin for dissipation.

Distance: Inverse Square Law

• The intensity of radiation from a radioactive point source follows the inverse square law, i.e., as distance increases, the intensity decreases proportionally to the square of the change in distance. • Consequently small changes in distance near a source mean large changes in radiation exposure.

Cold-Related Problems

• The most common problems related to cold exposure are: • Hypothermia • Frostbite • Cold stress is often associated with outdoor occupations, but even moderately cold environments inside can pose a hazard. Industries where cold stress could be an issue include: • Outdoor maintenance • Search and rescue workers • Construction • Utilities • Refrigeration

Importance of Hydration

• The most easily controlled factor in heat tolerance is the hydration level of workers. Fluid replacement lowers body temperature and cardiovascular strain during work in the heat, both of which are linked to heat stroke probability. • Providing substantial amounts of fluids to workers is considered to be one of the most important precautions that can be taken to maintain the highest blood volume.

Radioactivity

• The property of some atoms to spontaneously give off energy as particles or rays. • The atoms that make up the radioactive materials are the source of radiation. • Any electromagnetic or particle radiation capable of producing ion pairs by interacting with matter, i.e., ionization. • Ionization: Removal of an electron resulting in an ion pair -- electron (e-) and the residual atom (+). • Ionization alters the media occurring within, e.g., cell injury and/or death, change in cell reproduction, division, mutation. • Scope: alpha, beta, positron, neutron and proton particles, and x-ray and gamma rays.

Monitoring

• The thermal environment can be assessed by measuring its thermal components: • Dry bulb (air) temperature • Psychrometric wet bulb temperature • Natural wet bulb temperature • Globe temperature • Relative humidity • Vapor pressure • Dew point temperature • Air velocity • Mean radiant temperature

WindChill Index (WCI)

• The windchill index (WCI) represents the most universally accepted scale for describing the combined cooling effects of air temperature and wind velocity. • The index was developed using the freezing rate of a container of water • Provides a means of estimating those combinations of temperature and wind speed likely to freeze human flesh. • WCI provides a more accurate description of cold thermal conditions than air temperature alone because, at constant temperature, the risk of tissue freezing increases with air movement (convection). WCI = 13.12 + 0.6215Ta - 11.37(Var0.16) + 0.3965(Var0.16) Where WCI = windchill index (ºC) var = relative air velocity (km/hr) Ta = air temperature (ºC)

7. Estimate Metabolic Heat

• Thermal balance is affected by cumulative heat load • Consider all tasks and rest periods to assess metabolic heat

Biological Hazards

• Those agents capable of interacting with living cells/tissues and as a result of that interaction propagating itself (or its effects). - Bacteria - Fungi - Parasites - Prions - Rickettsia - Viruses (other than Arboviruses) - Arboviruses

Octave Band Analyzer

• To analyze sources and/or develop controls, the frequency content of the sound, not just the sound levels, must be determined • Audible frequencies are usually divided into 9 octave bands from 31.5 to 8000 Hz • Spectrum is typically analyzed in 1/3 octave bands using a Type 1 SLM

Monitoring Body Weight

• To detect dehydration, consider monitoring body weight very carefully. It is suggested that workers try to drink enough to make up for about 80% of the working sweat loss. For example: • If workers lose 1 kg of sweat, they need to replace the lost sweat with 800 mL of fluid intake. • Between shifts, the remaining deficit should be recovered so that workers start each shift fully hydrated. • Workers chronically exposed to hot environments should have their body weights monitored. • NIOSH suggests that body weight loss in a workday should not exceed 1.5%. • It may take a great deal of effort for workers to maintain body weight within 1.5% over the course of a work shift when engaged in heavy work resulting in heavy sweating. • The goal should be to achieve complete rehydration before the start of the next shift.

Mycotoxins

• Toxins produced by fungal metabolism • Diverse chemical compounds • Some are cytotoxic, carcinogenic, or cause immune system disruption. • Routes of exposure: inhalation, ingestion, dermal. • Current consensus: not a major IAQ threat; however, that may be more a reflection of research than true epidemiology and toxicology.

Phons

• Two different 60 decibel sounds will not in general have the same loudness. • Saying that two sounds have equal intensity is not the same thing as saying that they have equal loudness. • Sound loudness is a subjective term describing the ear's perception of a sound. It is related to sound intensity but can by no means be considered identical to intensity. • Since the human hearing sensitivity varies with frequency, it is useful to plot equal loudness curves. • Since 1000 Hz is chosen as a standard frequency, then each equal loudness curve can be referenced to the decibel level at 1000 Hz. This is the basis for the measurement of loudness in phons. • If a given sound is perceived to be as loud as a 60 dB sound at 1000 Hz, then it is said to have a loudness of 60 phons.

thermal stress

• Unacclimatized workers exposed to moderately warm temperatures or acclimatized workers exposed to hot temperatures should be continuously monitored to detect signs of potential heat injury, including: • Heat Stress • Heat Exhaustion • Heat Cramps Heat Rash

Arboviruses

• Viruses transmitted or borne by insects • Examples - West Nile Virus • Spread by mosquitos preying on birds - Ebola Virus • Extremely fatal (70% in African outbreaks)

Evaluation

• Whether a worker is cooling off or heating up depends on the balance of heat production through metabolism combined with heat gains or losses caused by interaction with the environment • Work involves the production of energy through metabolism, so workers are constantly producing heat. The higher the work rate is, the higher the rate of heat production. • The body uses metabolic production to help control body temp. Hence, shivering is an involuntary mechanism that causes the muscles to raise their metabolic rate to produce more heat. • Lethargy reduces the metabolic rate and results in less heat production. • At any given moment, different parts of the body are individually generating various amounts of heat and experiencing different interactions with the external environments, making the heat balance equation very complex. • This partly explains why simple equations cannot be used to accurately predict how workers will respond to a given environment. • However, understanding the heat balance equation is very useful in predicting thermal problems for workers and in devising solutions. • Because humans are so highly variable, the only way to determine the true thermal strain is to measure the individual's response. • In hot environments, deep-body temperature should be monitored as the best single gauge of heat strain. • In the cold, skin temperature is also important, because frostbite can easily occur while deep body temperature is normal.

Equivalent Chill Temperature (tch)

• Windchill reflects the cooling power of wind on exposed flesh and is commonly expressed as an equivalent chill temperature (tch), in ºC. • The tch is the temperature under lower wind (v = 1.8 m/s), which would provide cooling of the skin • In other words, the same windchill index (WCI) equivalent to that found with other combinations of temperature and wind. • Flesh may freeze within 30 seconds in the high danger area (<-60ºC), and within 1 minute in the near danger area (-60 to -30ºC). • Temperature and wind speed combinations in the low danger (-30 to +10ºC) area pose potential cold injury problems, unless the skin is completely dry and exposure time is <5 hours. tch = (33 - (WCI / 22) • When equivalent chill temperature is below freezing, cold injury can occur. The WCI does not recognize the amount of clothing being worn, but relates instead to bare skin such as the face and hands. • WCI exaggerates the importance of wind for the person dressed in heavy clothing and having face/hand protection and therefore provides values that are conservative.

Worker Selection

• Worker selection as an administrative control raises ethical and moral issues. • For example, excluding women from some hot jobs may be unethical and illegal discrimination, but exposing known pregnant women to jobs that threaten heat strain is certainly unethical. • Keeping workers with heart conditions from performing certain jobs may be ethical in some situations and unethical in others, depending on the circumstances. • Ethical issues must be considered on a case-by-case basis. • Can workers be selected based on the nature of the work? What about other criteria? • For example, an acclimatized, fit worker generally would be expected to tolerate greater heat stress than an unfit, unacclimatized worker. • The only real way to determine worker tolerance is to observe workers over a period of time to see who is most tolerant of a given work load and environmental combination. • Measuring deep-body temperature response to work would be desirable but may be impractical.

Heat Stroke

• Workers in the early stages of heatstroke typically have hot, dry skin • However, in exertional heatstroke, the skin can also be wet • The skin is typically red but may be mottled or pale blue-gray (indicating very low oxygen delivery) • Deep-body temperature will be very high • The person may evidence mental confusion or lose consciousness • Breathing may be faster and deeper than normal • All workers who may be exposed or supervisors of workers that may be exposed to heat stress, should know these symptoms • Heatstroke is a life-threatening medical emergency, and trained medical help should be summoned immediately, even if diagnosis is uncertain.

Industrial Radiography

•Gamma & x-ray radiation sources. •Commonly Iridium-192 & Cobalt-60. •Gas & oil pipelines, pipes, boilers pressure vessels in chemical plants, vehicles, and aircraft.

Building Factors

•Naturally-ventilated •Natural building materials • Mechanically-ventilated • Synthetic materials -Closed/tight envelope • Age of initial construction • Architectural design • Building materials • Subsequent renovations • Tight or loose envelope (infiltration/exfiltration) • Floor plan (open, offices, cubicles) • Occupancy (what's happening on adjacent floors?) • Direct sun/partial shade/downtown Manhattan • Maintenance & energy conservation practices

Inverse Square Law

•The intensity of radiation from a radioactive point source follows the inverse square law, i.e., as distance increases, the intensity decreases proportionally to the square of the change in distance. •Consequently small changes in distance near a source mean large changes in radiation exposure. I2 = I1 [d1/d2]_2 •Near field vs far field conditions.