Gases, Vapors, Solvents & Particulate Matter

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Solvents and Solvent Vapors very high concentrations

(1000s ppm), solvent vapors may cause simple asphyxiation. This is most likely to occur in confined spaces.

Solvents and Solvent Vapors high concentrations

(100s ppm), solvents tend to have a rapid effect on the CNS, resulting in dizziness, disorientation, confusion, euphoria, and giddiness. Prolonged exposure at high levels can lead to loss of consciousness, paralysis, convulsion, and ultimately, death.

Particles of dust are respirable when size is

(<10 μm).

Liquid nitrogen

-Wear proper safety gear when handling to prevent contact or inhalation of the extremely cold vapor. -Cover and insulate skin to avoid exposure, Because it boils so rapidly, the phase transition from liquid to gas can generate a lot of pressure very quickly. -Do not enclose liquid nitrogen in a sealed container, as this may result in it bursting or an explosion

Compressed gas cylinders should

-be securely stored with DOUBLE CHAINS to prevent falling and breaking, -be stored in a WELL VENTILATED area, -have SIGNAGE to indicate the potential hazards, -be STORED and TRANSPORTED with cap on to protect valve & be protected from HEAT, which can generate greater pressures inside than the cylinder was designed to withstand (e.g.: in welding Area)

Electrostatic precipitation...

...is also used in some industrial applications. The application of paint/powder coats make use of electrostatic precipitation. The paint is given a charge, and the surface to be coated is given the opposite charge.

Vapor pressure...

...refers to the pressure exerted by a vapor when it is at the same temperature as its condensed phase (liquid or solid)

Vapor pressure..

..depends highly on temperature

Electrostatic precipitation..

..does not appear to be the case in the respiratory tract.

Additive.

.The more closely the PM-related health effects are, the more appropriate it is to judge them to be

Gases.

.are materials that are in the gaseous state at normal temperature (25°C/80°F) and PRESSURE (1 ATM)

Personal sampling.

.assures that the filter goes wherever the worker goes, and collects particles representative of the airborne concentration of PM wherever that employee works.

Interception.

.is most effective for mid-sized particles.

Surface sampling for PM.

.is not needed where the contaminant is of low toxicity, since a visual observation will suffice.

General area sampling.

.is used extensively in specific settings, asbestos abatement in particular/ building maintenance and renovations

Vapor pressure.

.is very temperature dependent as the temperature rises, the airborne concentration of an equilibrium mixture will rise.

Dry swipe sample.

.method is the least reliable method and it is only used to determine type of PM

Wet swipe sample.

.procedure is more reliable than the dry swipe method since it collects all the particles on the surface. The particles concentration is measured by dividing the number of particles by the surface area

Electrostatic precipitation.

.widely used for air pollution control. Some air filters are designed to charge airborne contaminants and/or attract charged particles.

Under EPA fibers must be

> 0.5 micrometer and meet a 5:1 aspect ratio to be counted under the microscope.

Under OSH and NIOSH microscopic counting rules the fibers must be

> 5 micrometer long and have an aspect ratio of at least 3:1 to be counted.

Transient illness

A few hours of overexposure to some metal fumes from welding can result in

Full calibration

A number of commercially available static-type calibration kits are available for commonly measured gases and vapors. These kits usually contain one or more cylinders filled with a known concentration of a specified gas air mixture. Once the kit is attached to the instrument, a sample of the gas air mixture is permitted to flow into the device. The meter reading of the instrument is then compared with the known concentration of the sample to verify proper response.

Volatile

A substance with a high vapor pressure at normal temperatures (room temperature)

Asphyxiation risk

Adding a lot of nitrogen to the air reduces the relative amount of oxygen

Sedimentation (settling)

All particles are acted upon by gravity. If the particle settles onto a surface, it will be removed from the aerosol

Active Method

Also known as personal sampling, assures that the filter goes wherever the worker goes, and collects particles representative of the airborne concentration of PM wherever that employee works

Lead and Asbestos

An example of a non interactive concurrent exposure would be. While they are both primary occupational hazards, their target organs, health effects, and mode of action are very different. When both exposures are measured simultaneously, the results are treated independently, and if both exposures are below the appropriate limits, the operation is in compliance.

Inertial impaction

As a particle moves within an aerosol, it gains momentum. When an aerosol is forced to change direction abruptly, the gas phase does so easily, however, a suspended particle tends to resist the change in direction and deviates from the airstream. This may cause the particle to impact on the surface (e.g., lung, filter) and stick there.

Environmental Justice Movement

As many workplaces that make intensive use of diesel engines are located in economically disadvantaged neighborhoods

Diffusion (Brownian movement)

As the very small (submicron) particles flow with the air, they tend to wander from the airflow lines, and may bump into a collection surface and be removed from the aerosol.

Synergistic combination of toxicants

Asbestos and cigarette: Latency period of mesothelioma for a smoker person who is exposed to asbestos is 10 years instead of 30 years for a non-smoker, Carbon tetra chloride and ethanol, Particulate matters and So2, Ethanol and alcohol will cause immediate nervous system poisoning.

Organic and Inorganic gases can produce a multitude of hazards

Asphyxiants, Acute Toxins, & Chronic Toxins

Examples of biological sampling

Benzene in the urine, Cadmium in the blood and the urine, Lead in the blood

Inorganic Acids and Bases: Strong acids and bases are

CORROSIVE and can burn the skin and mucous membranes.

Electrostatic precipitation

Charged collection surfaces will attract and hold oppositely charged particles. Most airborne particles carry some net charge.

Nature of health problems caused by inhalation of PM is influenced by a number of factors

Chemical Composition, Isotopic Composition, Crystalline and Structural, Shape of Particles, & Size of particles

Amorphous quartz (non crystalline silica)

Chemically identical to quartz and other free crystalline silica, but lacks a fully formed repetitive crystalline structure. (not same shape and structure). As a result of this difference, glass, natural or manmade, is of low toxicity.

Vapors

Chemicals that are liquids at normal temperature and pressure will exist partially in the gaseous phase

Smoke

Consists of carbon or soot particles resulting from the incomplete combustion of materials.

Direct reading indicator tube

Contain chemical reagent that is sealed in glass. The tubes are broken open and the chemical reagents are exposed to the atmosphere that is tested. The airborne contaminants are indicated by a color change caused by chemical reactions between the contaminant and the tube reagent.

Arsenic and cadmium

Diesel smoke can also contain other carcinogenic PM such as:

Solvents and Solvent Vapors low concentrations

Direct contact with the skin can cause irritation, defatting, and dermatitis

Liquid maybe flammable or explosive

Flash point is the lowest temp. at which it gives off enough vapor to form an ignitable mixture with the air near the surface of the liquid or in a vessel.

Fumes

Form when the material from a volatilized solid (e.g., arc welding) condenses in cool air.

DIFFUSION

Gases spread rapidly throughout a room by

Passive method

General area sampling, accomplished by using high volume pumps to move large quantities of air through a filter medium

Upper flammability limit (UFL)

Highest concentration (percentage) of a gas or a vapor in air capable of producing fire in the presence of an ignition source (arc, flame, heat).

Vacuum collection

If dust is visible on the surface, samples can be collected by using a micro-vacuum. The filter cassette is then sent to a laboratory for analysis.

Wet Swipe Sample

In this method, a filter or a swipe tab is pre wetted with water or another liquid prior to use.

Overall deposition is the sum of five primary mechanisms of particle deposition

Inertial impaction, Interception, Sedimentation, Electrostatic Precipitation, Diffusion

Other Chemical Monitoring Instruments

Infrared (IR) analyzers that measure compounds that absorb IR, Flame Ionization detectors (FID) measure a wide variety of chemicals

DPM

It has been shown to be carcinogenic and cause a range of respiratory tract and cardiovascular problems.

Synergistic

It is the situation where the combined effect of two chemicals is much greater than the sum of the effects of each agent given alone, for example: 2 + 2 >> 4 (maybe 10 times or more) Some PM exposures are synergistic.

Aerosols

Liquid droplets or solid particles that fine enough to remain dispersed in air for a prolonged period.

Functional/bump test

Many direct reading instruments require a functional test in situations where frequent confirmation of the sensor's performance is important because of hazardous conditions.

Asphyxiants

Many of these elements and compounds have no or very minimal odor, and thus have poor warning properties.

Inhalation

Most important route of exposure for most particulate matter

Air Sampling

Most samples collected by this technique, particles are removed from the aerosol by filtration, impaction, or electrostatic precipitation. The collected particles then will be analyzed under the microscope

25 ppm

Nitric oxide (NO) has a Threshold Limit Value of

Acute Toxins Delayed

Nitrogen dioxide exerts its effects several hours after exposure.

Surface Sampling

PM from clothing or skin surfaces (collected as an indication of dermal exposure). Commonly used in research on particles that pose substantial transcutaneous hazards (e.g., pesticides).

Aerosols can be classified into two different kids, based on size of particles

Polydesperse and Monodesperse

Isotopic Composition

Radioactive atom.

Electrostatic Precipitator

Radon example sample testing

Examples of antagonistic effects

Snake bite antidotes, Atropine for organophosphate, Dimercaprol for arsenic and inorganic mercury, Activated charcoal for most poisons

Particulate matter (dusts)

Solid particles of minerals or organics generated by handling, crunching, grinding, impact, or detonation.

Acute Toxins Immediate

Some gases (e.g., phosphine, arsine) can cause acute fatalities with short exposures to relatively low concentrations.

Dual phase monitoring

Sometimes you need to sample for particulate matters and gas or vapor at the same time to get an accurate and full understanding of the exposure

Mists

Suspended liquid droplets generated by condensation of liquids from the vapor state or by breaking up a liquid into a dispersed state.

Personal sampling technique is also considered for the

TLV STEL, TLV C, and the Excursion Limit

Interception

The particle follows the airstream fairly well but still makes contact with the surface and sticks.

Particle deposition

The removal of a particle from an aerosol state

Photoionization Detectors

These types of detectors utilize Ultraviolet light (UV) and they are commonly used on hazardous waste sites.

Electrochemical Detectors

They are specific detectors, commonly measure CO, H2S, and O. A chemical reaction creates an electrical current when the gas enters the cell.

Additive

This action occurs when the combined effect of two or more chemicals is equal to the sum of the effect of each agent given alone (they do not interact in a direct way) for example: 2 + 2 = 4

Potentiation

This effect results when one substance that does not normally have a toxic effect is added to another chemical, making the second chemical much more toxic (example: 0 + 2 > 2 (0 has no effect. If we add 0 to 2 then we will create a chemical that has more toxic effect than chemical 2.))

Surface sampling is conducted for several reasons

To determine adequacy and effectiveness of housekeeping controls, To determine adequacy and effectiveness of engineered controls, When working on laboratory fume hoods, Prior to releasing excess equipment for reuse, utilization, sale, or donation, When necessary to determine what metals are/were used in an area in the past, Where the contaminant has a high percutaneous toxicity, & Whenever working with radioactive PM.

Chemical Composition

Toxic nature of the particle & Solubility of the particle (e.g., how rapidly is it removed from the body, where in the body is it transported-hydrophilic or lipophilic)

Size of Particles

Toxicity of some agent depends very directly on the size of the individual particles to which people are exposed.

When opening drums of liquids (especially hazardous waste drums)

Use a non-sparking tool (brass), we do not want to increase the temperature. Make sure you don't create friction when opening a waste drum with a low boiling point hazardous substance.

Lift tape

Utilizes pressure-sensitive tape to determine the presence of particulate contamination.

Dermal Exposure

When inhalations exposures are controlled, this may be the major route of entry.

The Excursion Limit

Worker exposure levels may exceed 3 times the TLV TWA for no more than a total of 30 minutes during a workday, and under no circumstances should they exceed 5 times the TLV TWA, provided the TLV TWA is not exceeded. But this is not applicable for STEL.

Gas

a formless fluid that completely fills its container and EXERTS AND EQUAL PRESSURE IN ALL DIRECTIONS.

Asbestos fibers are said to have

a high aspect ratio (length divided by width).

When using direct reading instrumentation,

a much greater number of samples and much more information can be obtained and evaluated.

All substances are poisons, there is none which is not a poison, but the concentration is what differentiates

a poison and a remedy.

Use liquid nitrogen in

a well-ventilated area.

Reactivity of the gas may be important: After the exposure, some of the inhaled chemical compounds react with the moisture of the respiratory system's mucous membrane. This reaction forms

acids and toxic substances that causes irritation to the respiratory system.

Combustible gas indicators require

adequate oxygen to work properly. The instrument will give a false result in oxygen deficient area. Many also include detectors for oxygen or toxic gases.

Monodesperse

aerosols that contain one size partcles. This kind is used in research.

Flammable range includes

all concentrations of vapor in the air that are between the Lower Flammable Limit (LFL) and the Upper Flammable Limit (UFL).

AED value

also determines where the particle size will deposit in the respiratory tract

Flammability: Some gases ignite spontaneously when exposed to air

and cause fire hazard or some time explosion hazard

When both exposures are measured simultaneously the TWA fractions of the respective exposure limits found for each agent are added together

and if the value exceeds 1.0, then an over-exposure situation is assumed to exist.

Flammable range

another factor to rate fire hazard of flammable gas or liquid

Flammable and combustible liquids

are classified according to their flash points and boiling point

Particles making up the fume

are extemely fine (usually < 0.1 μm) and respirable.

Pre Existing Health or Genetic Status: Occupational exposure limits for particulate matter (or other classes of stressors)

are generally set for "healthy" workers.

Most important factors in exposure potential

are how the material is used and what controls (e.g., engineering, PPE) are in place.

Typically, Smoke particles

are less than 0.1 μm in size.

Personal integrated industrial hygiene air samples

are most typically collected onto filters placed in the breathing zone of the worker (within ~9 inches of the nose and mouth) with air drawn through the filter at the rate of 0.5 to 4 liters per minute.

The health consequences of concurrent inhalation of cigarette smoke and asbestos exposure

are much greater than the sum of the parts, on the order of 50-100x. Lung infection and exposure to pneumoconiosis producing dust often seem to act synergistically.

Combustible Gas Indicators (CGIs)

are nonspecific detectors. Each indicator contains a sensor that detects any type of combustible gas or vapor in the working area and then display the present of the Lower Flammable Limit (LFL) of these gases or vapors.

Particulate monitors

are particle counting devices that use laser technology and light scattering principles to count individual particles.

Particles of dust

are respirable when size is (<10 μm) (less than)

Filter cassettes

are used for microscopic fibers.

Combustible liquids

are with a flash point greater than 100 F

A court decision has made it clear that a woman cannot be forcibly discharged or even shifted from one job to another to protect her fetus

as long as her exposure and biological monitoring results fall below the minimum OSHA standards.

Asbestos always has an aspect ratio of

at least 10:1.

Dose (concentration and duration)

at some point,everything becomes toxic.

Crystalline and Structural: For example, the toxicity of silicon depends not on the intrinsic toxicity of the element

but on the types of compounds silicon makes with other elements and their crystalline structure

Some types of PM may be hazardous

by ingestion or skin contact.

From the nasopharyngeal region

by physically by blowing the nose clears the particulate matters from the aerosol in the respiratory system.

From the pulmonary region

by the macrophage (asbestos ruin it), or the lymphatic system clears the particulate matters from the aerosol in the respiratory system.

From the tracheobronchial region

by the muco ciliary escalator mechanism (Mucous) clears the particulate matters from the aerosol in the respiratory system.

Number of samples can be determined

by the number of employees in the working area.

PM that persists in lung tissue for weeks or months may

cause chronic lung disease including lung cancer

Species with high specific activities emit a lot of ionizing radiation per unit time and mass, and thus more rapidly affect tissue

causing genetic and somatic cell damage.

Color badges

change their color to indicate a chemical exposure. Color badges are easy to use and they are usually used for acutely toxic gases.

An instrument's response to a concentration of a substance can shift as a result of a variety of factors

chemical degradation of sensors, physical damage, drift in electronic components, exposure to extreme environmental conditions (e.g., high temperatures), extremely high contaminant exposures, or exposures to poisons or inhibitors.

NIOSH analytical method to sample total elemental carbon is difficult to use in environments where

coal dust or organic dust is also present, as these substances lead to positive interference.

Liquid nitrogen (Cryogenic Liquid)

cold enough to cause severe frostbite upon contact with living tissue.

Confined space combustible gas detectors

contain at least three different sensors for LEL, Oxygen, and toxic gas (Co or H2S)

Polydesperse

contain range of particle size. This kind is very common in the workplace.

Remember that in the UFL atmosphere, ventilation control

could be a bad choice because ventilation will reduce and lower the concentration of the flammable gas and produce a mixture within the flammable range before the safe concentration limit can be reach.

In both air sampling methods, analysis of PM samples

could be by microscopic counting or respirable mass fraction

Slow release

decomposition, rotting

From the point of view of chemical kinetics, reaction rates

depend on some factor of concentration.

Airborne concentration of a solvent vapor

depends on the vapor pressure, which is a measure of the volatility of the solvent.

Respiratory Cancer

deposition of radioactive particles in the lungs presents the risk of.

Temperature

directly related to the vapor pressure of any chemical.

Expanded OSHA standards for PM

do generally require some medical evaluation of workers before significant exposure to a specific PM (e.g., lead, asbestos, cadmium, arsenic).

OSHA in general

does not require pre-exposure medical assessment for workers who will be exposed to hazardous particulates. But, the Expanded OSHA Standards (29 CFR 1910.1001-1052) are an exception to this rule.

Volatile chemicals are a big concern in the field of safety and health

due to the high potential of exposure.

Insoluble PM

either will be cleared from the respiratory tract by the various defenses of the lungs, or may remain in the lungs for an extended period of time

Class IB FL Boiling Point

equal to or greater than 100°F

Class II CL Flash Point

equal to or greater than 100°F, but less than 140°F

Class IIIA CL Flash Point

equal to or greater than 140°F, but less than 200°F

Class IIIB CL Flash Point

equal to or greater than 200°F

Class IC FL Flash Point

equal to or greater than 73°F, but less than 100°F

If a liquid is spilled, some will evaporate and, over time,

equilibrium may be established between the gas and liquid phases.

Bioassays (e.g., blood, urine analysis)

exist for many particulates that provide an indication of actual absorbed dose or biological changes resulting from absorbed dose.

Concurrent Exposure to other Toxic Agents

exposure occurs to more than one type of PM, or PM plus gases, vapors or infectious agents. While in many cases these multiple exposures do not interact, in some cases they may interact additively or synergistically.

The range of PM sizes under consideration is

five orders of magnitude (0.001 μm to 100 μm).

In a comprehensive industrial hygiene program, all women should have their workplace evaluated

for potential exposure to teratogenic or fetotoxic exposures, including radiation exposure when applicable.

Solid particles of minerals or organics

generated by handling, crushing, grinding, impact, or detonation. As used in industry, particulate matter (PM) is used to describe airborne solid particles that-range in size from 0.001 μm to 100 μm in diameter (1 μm = 0.00004 in.)

A liquid at high pressure

has a higher boiling point than when that liquid is at normal atmospheric pressure.

A liquid at low pressure (or in a vacuum)

has a lower boiling point than when that liquid is at normal atmospheric pressure.

Toxicity occurs after the particulate matter

has been removed for the air by deposition in the respiratory tract

DPMs carcinogenicity

has traditionally been ascribed to its high content of polynuclear hydrocarbons, which are known carcinogens.

AED value predicts

how a particle will behave when inhaled or passing through a respirator or sampling filter much more reliably than the actual size of the particle.

Direct read instruments for chemical contaminants

identify and/or quantify the concentration of many gases, vapors, and particulates in air, in real time or near real time.

Effectiveness of sedimentation

in a still aerosol is proportional to the particle's mass, and large particles settle out much faster than small particles.

Keep in mind that particles behave differently in different areas of the respiratory tract

in nasal area, tracheobronchial, and pulmonary region

Sedimentation

in small air ways where velocity of air is low and gravity is considered

Surface sampling for PM

in some workplaces is useful as an adjunct to air sampling. This may include taking wipes of surfaces or sampling from an employee's skin or clothing.

Samples can be collected

in the field and returned to the laboratory for analysis, or they may be collected and analyzed on the spot with direct-reading instrumentation.

Particle deposition happens

in the respiratory tract, on industrial hygiene air sampling filters, and inside filter-bag houses in factories (control method).

Organ systems that are affected by some solvents

include the liver, the kidney, the CNS, and the peripheral nervous system.

Low readings could falsely

indicated that no hazard is present

Substantial exposure to PM can

induce a wide variety of biological responses ranging from acute to chronic, local to systemic, mild to life threatening

pneumoconiosis

insoluble PM result in a type of illness (dust in the lungs). The term has been widely used to describe a number of lung diseases after inhaling particulate matters

Aerosol

is a collection of suspended particles and the surrounding gases.

Pressure sensitive adhesive (PSA) tape

is a continuous flexible strip of cloth, paper, metal or plastic coated on one or both sides with a permanently tacky adhesive at room temperature which will adhere to a variety of surfaces with light pressure (finger pressure) with no phase change (liquid to solid)

Exposure to DPM

is a known occupational hazard to truckers, railroad workers, and underground miners.

Vapor pressure

is a measure of the concentration of the chemical in the air at equilibrium.

Decomposition

is a slow combustion refers to reactions that occur between a fuel and oxidant that accompanied by release of heat and conversion of chemicals.

Diesel particulate matter (DPM)

is a specific form of smoke from the diesel cycle internal combustion of diesel fuels.

Pregnancy

is a temporary medical condition that may predispose either the pregnant woman or her fetus to occupational disease.

General area sampling

is accomplished by using high volume pumps to move large quantities of air through a filter medium, Filters are often stacked to remove progressively finer particles for the sampled air.

Direct measure

is also used widely to measure the flammable level, combustible level, oxygen level, and toxicity level of particles in the working area

Equilibrium vapor pressure

is an indication of a liquid's evaporation rate and relates to the tendency of atoms/molecules of the substance to escape from the liquid (or solid).

Impaction

is most effective for large and dense particles in high-velocity air.

Any concentration that is lower than the LFL

is not sufficient to form an ignitable mixture.

Radon

is one of the noble gases, which generally refuse to react with other compounds and, therefore, are almost always found as gases & is a naturally occurring gas that is usually formed by the radioactive decay of uranium. Even though the gas is radioactive, it is not usually an occupational hazard, as it is not significantly absorbed as a gas when in contact with the surface of the lungs.

Concentrated hydrogen fluoride (HF)

is particularly corrosive to tissue and bone. Serious tissue damage may result without the person being aware of it.

Bump test

is performed by briefly exposing the instrument to a concentration of a substance in excess of the lowest alarm set point for each sensor. If the response of the instrument is within an accepted tolerance, then the calibration is verified.

Lower flammability limit (LFL)

is the lower end of the concentration range over which a flammable mixture of gas or vapor in air can be ignited at a given temperature and pressure. And it is usually 10 %

Class 1A

is the most hazardous because it ignites rapidly due to its low flash point.

Antagonism

is the opposite of synergism. It is the situation where the combined effect of two or more compounds is less toxic than the individual effects for (example: 4 + 6 < 10)

As used in industry, particulate matter (PM)

is used to describe airborne solid particles that range in size from 0.001 μm to 100 μm in diameter (1 μm = 0.00004 in.).

Personal sampling

is used to monitor the average exposure for an individual over an 8 hr working period of time as determined by taking one or more samples during the 8 hr working period (TWA).

Asbestos

is usually fibrous.

Quartz (crystalline silica)

is very toxic to lung tissue.

Dry swipe sample

is when the surface is rubbed with a dry filter or special swipe tab.

Pure silicon

is with a low toxicity when inhaled.

As radon radioactively decays by the release of an alpha particle

it turns first into radioactive polonium

Impaction

large and dense particles/due to high velocity air changing direction

Class IA FL Boiling Point

less than 100°F

Class IA FL Flash Point

less than 73°F

Class IB FL Flash Point

less than 73°F

Rapid release

light is produced (eg: glowing amber, flame)

Silicates

make up the bulk of the earth's crust, and vary in toxicity from very toxic to relatively inert.

Sampling and analysis for DPM poses a range of difficulties. When using standard filter methods

many other dusts can be collected as well, resulting in positive interference.

Silica

may be found or made in both a non-crystalline form (glass), or a crystalline form (quartz).

Chronic inhalation of very fine, respirable particles of quartz

may lead to silicosis.

Skin contact with dusts alone

may result in burns, sensitization, systemic toxicity, or cancer.

Interception

medium size fibers

To be of inhalation concern, a particle must

not be too big, as it would not stay suspended in the air long enough to be inhaled, nor too small, as it then takes on the characteristics of a gas rather than a particle.

Aerodynamic Equivalent Diameter. (AED)

of a particle is the diameter of a unit density sphere that would have the identical settling velocity as the particle of interest

PM that is cleared from the respiratory tract is

often swallowed, giving the material another shot at absorption into the body via the digestive tract.

Shape of Particles

often the defining characteristic that makes a particle toxic.

For a working area that has 7 employees or less

one sample is required for each employee.

At higher concentrations, NO reacts rapidly with

oxygen to produce nitrogen dioxide (NO2), which has a TLV of 3 ppm (proposed to drop to 0.2 ppm).

Spray painting

poses a greater exposure risk for the worker than brush or roller application.

Co exposure to any of the pneumoconiosis

producing dusts, as they produce variably related conditions.

An appropriately selected direct reading instrument may be used to

quickly establish a safe zone around a chemical spill, and are often used to assess the exposure of workers to hazardous chemicals.

Organic Compounds

readily permeate the skin or glove materials.

Reducing concentrations

reduces the potential for exposure by limiting the amount of toxic product formed or volatilized

A particulate matters

refers just to the suspended solid or liquid matter.

NIOSH has developed an analytical method meant to

sample for total elemental carbon as a simple indicate for DPM.

Classic chronic lung toxins that can cause pneumoconiosis

silica, coal dust, and asbestos.

Particles larger than about 100 μm

simply fall to the ground quickly

Deposition by diffusion

slow movement of small particles favors

Cold nitrogen gas is heavier than air

so the risk is greatest near the ground.

Chemical Composition

sometimes the primary driver for the toxicity of a material

Particles smaller than about 0.001 μm

start to act like gases, rather than like particles.

Diffusion

submicron particles

PM can indirectly cause

systemic toxicity by triggering inflammation in the lungs.

Airborne radon

tends to accumulate where uranium is stored or inside poorly ventilated basements or in certain geographical locations such as mines

The use of compressed gas cylinders has inherent dangers in their handling if the cylinder were to fall over and the valve snap off

the cylinder can become a projectile.

Air Sampling occupational exposure purposes

the eight hour time weighted average is the most commonly measured value

One concern about the cryogenic liquids is

the frost bite from extreme cold.

For a mixture of two or more flammable gases with LFL of ≤ 10% for each gas

the gas that has the smallest (LFL) will be the one that poses the most flammability hazard.

The higher the vapor pressure

the higher the concentration of the chemical at equilibrium.

The higher the temperature

the higher the vapor pressure.

High readings could lead to

the implementation of unnecessary control measures

Typically, samplers are set up around

the perimeter of an isolate asbestos dust containment area as a means of verifying the adequacy of the controls. These samples are typically taken using aggressive techniques, traditionally using a leaf blower and fans to stir up any settled or residual dust and make it accessible to air filter.

For more of a substance to evaporate (i.e., for the substance to boil)

the temperature must increase.

After radon turns to Radioactive polonium

then through several other radioactive isotopes including two forms of radioactive lead, and finally to lead-206. These intermediate radioactive materials are charged particulate matter and rapidly attach themselves to oppositely charged particles in the air.

As the nitrogen evaporates

there is a risk of violent oxidation of organic matter.

Because asbestos fibers can travel on air currents through the lung lengthwise, like an arrow

they can penetrate much deeper into the lung than a non fibrous particle, As a result, asbestos fibers can make it to the alveolar region of the lungs.

For the same liquid if different boiling point

this depends on the pressure of the atmosphere.

For asbestos control, the best method is

thoroughly wet the surface before removal or renovation

DPM significant contributor

to community cardiovascular morbidity and mortality in communities.

Some compounds react spontaneously in moist air (before inhaling them)

to form compounds that cause irritation to the respiratory system.

Surface sampling is used

to sample for large particles because they settle on the surfaces and do not suspend in the breathing zone.

Decomposition of organic material may produce

toxic (e.g., hydrogen sulfide) atmospheres & flammable (e.g., methane) atmospheres.

Once Asbesto fibers deposited in this region of the lungs, it is believed that the fibers

trigger an ineffective immune response by resident macrophages, which not only fails to remove the relatively insoluble fiber, but kills the macrophages in the process. This sets off a chain of immunological events, which results in scarring of the lungs and development of lung cancer.

Development of pneumoconiosis

typically requires years of exposure.

Soluble PM will be absorbed in

upper respiratory tract system.

General are sampling is also

used for sampling airborne bacterial and fungal spores.

Lower flammability limit (LFL)

usually expressed in volume per cent

Another concern is that if the cryogenic liquid spills, the spill

vaporizes rapidly, producing gas that is denser than the air which causes oxygen deficiency especially in a closed area

Electrostatic precipitation

when particles are charged

PM may also enter the lymphatic system

where they can dissolve or remain.

Any concentration above the UFL

will create an enriched mixture with the atmospheric oxygen. The atmospheric oxygen in this mixture is not sufficient to form an ignitable mixture.

Seven samples are enough for a working area

with 8 to 10 employees,

Flammable liquids

with a flash point < 100 F

Vapor pressures of liquids at ambient temperatures increase

with decreasing boiling points. If the boiling point is low - then we need shorter time to release the vapor

Eight samples are enough for a working are

with eleven employees or more.

Generally, Particles must be

≤ 2 μm to penetrate to the inner recesses of the lungs (less than/equal to)

Generally, particles must be

≤ 2 μm to penetrate to the inner recesses of the lungs.


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