Noise and Vibration Hazards

Control Methods: PPE

Anti‐Vibration gloves

Control Methods: Engineering

Mechanically isolate the vibrating surface with shock absorbers, e.g., Anti‐Vibration tools / seats -replace old springs in equipment

Sensorineural Hearing Loss (Noise induced)

- Caused by damage to the inner ear, or auditory nerve pathways in brain - Not reversible

3. Inner Ear

- Cochlea - Organ of Corti - Hair Cells - Auditory Nerve

OSHA Exposure limits:

- Eight-hour average exposure cannot exceed 85 dBA. - Single exposure cannot exceed 140 dBA. - Continuous exposure cannot exceed 115 dBA

2. Middle Ear

- Ossicles - Oval window

1. Outer ear

- Pinna - Ear canal - Tympanic Membrane

Control Methods: Administrative

- Training on safe work practices - having employees take frequent breaks -Job rotation

Presbycusis

- gradual loss with age, (affects 1/3 of those >75yo) due to gradual cumulative loss of hair cells and neurons - Not reversible

Noise Dose

-100% dose = 90dBA for 8 hours (or equivalent) -50% dose = 85dBA for 8 hours (or equivalent)

Hearing Conservation Program

-29 CFR 1910.95 -Program components: • Monitoring noise levels • Providing hearing protection devices • Informing and training employees • Conducting audiometric tests • Retaining records

Conductive Hearing Loss

-Caused by a mechanical problem in the ear canal or middle ear that blocks conduction of sound - reversible

At 85 dBA (TWA):

-OSHA requires a Hearing Conservation Program that includes: • Exposure monitoring • Training • Hearing tests -Hearing protection must be made available and is required for any individuals who have experienced a standard threshold shift*.

At 90 dBA (TWA):

-OSHA requires that employees wear hearing protection. -Employers must: • Supply hearing protection at no cost to employees. • Provide a variety of hearing protection types for employees to choose from. • Evaluate effectiveness. • Assure proper use.

HAV Symptoms

-White Fingers (Reynauds Syndrome) • Peripheral neuropathy, with or without increased cold sensitivity -Myelin sheath damage -Musculoskeletal disturbances, such as weakness, lancinating forearm pain, and bone and joint degeneration

Engineering Controls (3)

1. Absorption 2. Isolation 3. Damping (adding weight onto object to reduce vibration)

How sound travels through the ear... Three different forms of energy

1. Acoustic Energy 2. Mechanical Energy 3. Electrical Energy

Noise Controls: Hierarchy of Control

1. Identify sources of hazardous noise (equipment, areas, operations) 2. Determine if engineering controls can reduce or eliminate noise hazards 3. Identify and label noise hazards 4. Recommend enrollment of personnel in the HCP

Human Ear consists of

1. Outer Ear 2. Middle Ear 3. Inner Ear

Chemical (Ototoxicity) and Noise Exposure

Certain chemicals, called ototoxicants, may cause hearing loss or balance problems, regardless of noise exposure.

Personal Noise Survey Purpose:

Determine personnel occupational noise exposure during a work shift. Determine if personnel should be enrolled in the Hearing Conservation Program.

3. Electrical Energy

In the inner ear, the vibrations enter the fluid-filled cochlea where tiny hair-like cells—"hair cells"—convert them into electrical impulses that are sent to the brain by nerves and perceived as sound.

What is Noise?

Noise is sound that is not wanted by the perceiver, because it is unpleasant, loud, or interferes with hearing.

1. Acoustic Energy

Sound waves enter the outer ear and travel down the ear canal to the ear drum, which then vibrates

What is "Sound"?

The sensation resulting from stimulation of the auditory mechanism by air waves or other vibration

2. Mechanical Energy

The vibrations of the ear drum are transmitted to the inner ear by three small bones called ossicles

Whole Body Vibration (WBV)

WBV refers to mechanical energy oscillations transferred to the body as a whole (in contrast to specific body regions), usually through a supporting system such as a seat or platform.

Intensity (loudness) is a function of...

amplitude -0 dB is auditory threshold (log scale, so 0 dB is not the absence of sound) • 120 to 140 dB is pain threshold

At 80 dBA (TWA):

‒ Provide hearing protection. ‒ Encourage proper use. ‒ Create a Hearing Conservation Program.

Frequency:

• Also known as pitch • The number of cycles a sound wave makes per second • Measured in Hertz (Hz)

Baseline testing:

• Begins the audiometric testing regimen. • Determines the current hearing threshold of all employees. • Must be conducted within 180 days of employment. • Must be preceded by 14 hours of quiet time

Sound is a pressure wave...

• Consists of a repeating pattern of high pressure and low pressure regions moving through a medium • Amplitude of wave reflects loudness

Annual hearing tests:

• Employees must have worn their hearing protection during the previous shift. • A review of the noise reduction of the hearing protection used will be conducted. • The audiologist will work with the employee to check the fit of the hearing protection.

Retention:

• Exposure measurements • Audiometric tests • Training records

Providing hearing protection devices: Types of hearing protection devices:

• Foam plugs • Rigid plugs • Canal caps • Custom fitted molds • Circumaural devices (ear muffs) • Helmets

HAV Health Effects

• HAV can cause a range of permanent injuries to hands and arms including damage to the: - Blood circulatory system (e.g. vibration white finger) - Sensory nerves - Muscles - Bones - Joints

Hand‐Arm Vibration (HAV)

• HAV is vibration transmitted from work processes into workers' hands and arms. • Regular and frequent exposure to high levels of vibration can lead to permanent injury

Risk Factors for Hearing Loss

• Intensity of Noise (sound pressure level) • Duration of Daily Exposure • Frequency..etc

Negative effects of noise:

• Irritability • Reduced efficiency • Stress • Loss of sleep • Difficulty concentrating • Fatigue

Monitoring:

• Make use of proper equipment: • Examine all forms of noise: - Continuous - Intermittent - Impulse

The Noise Reduction Rating (NRR):

• Must be on all hearing protection devices used in the workplace. • Is an estimate of noise reduction when a hearing protection device is properly worn. • Is based on testing under controlled laboratory conditions. • Must be adjusted to account for real‐ world conditions.

If there is a threshold shift:

• Notify the affected employee within thirty days. • Have a physician evaluate the results. • Retrain and refit the employee for hearing protection.

Standard Threshold Shift (STS)

• Permanent hearing loss • Can be caused by long term overexposure. • Is related to damage in the inner ear. • Cannot be treated medically

Hearing protection devices must be:

• Provided at no cost. • Evaluated for noise attenuation. • Reviewed for effectiveness annually. • Replaced when necessary.

Temporary Threshold Shift (TTS):

• Ringing in the ears • Temporary Hearing Loss • Trouble understanding speech • Temporary hearing loss or dampening of sound after completing a shift

Administrative Controls:

• Rotating job tasks • Conducting preventive maintenance

Train employees on:

• The effects of noise on hearing. • Hearing protection: - Selection - Fit - Use - Care • The purpose of testing procedures.

Health Effects

• The most widely reported WBV injury is back pain. • Additional effect is: - Decreased concentration ability - Impaired vision - Loss of balance, fatigue

Decibels:

• Used to measure the power of a sound • Based on sound wave pressure • Frequency corrected and abbreviated as dBA • Determine noise exposure