Transcript Focus on 2006

Occupational Exposures
BY BILL EVANS – INDUSTRIAL HYGIENIST
Understanding
Occupational
Exposure
Dose – Response Curves
are different for all toxic
agents.
The most disconcerting
factor is that the most
harmful exposures come
from particles, fibers and
gases smaller than the
human eye can see.
“Targets” of OSHA Compliance

Updating of OSHA PELs Status – 11th Cir. Court
gutted PELs by vacating standards for 212
substances in 1991 moving back to levels of 1971

OSHA LEPs – Local Emphasis Programs vary slightly
by Region, but the items called out below are
consistent

Noise, Hazard Communication/GHS, Gut-Rehab,
Silica, Lead, Asbestos, Hexavalent Chromium,
Cadmium and Carbon Monoxide
Industrial Hygiene Method
of Assessment

Unhealthy noise exposure is used as an example
to show:

Pathway of Exposure

Body System Affected

Mode of Transmission

Symptoms of Exposure

Acute Effects

Chronic Effects

Health Codes: Legal Exposure Limits (PELs) &
Guidelines (TLVs, RELs, OELs)
Video of Hazardous Noise
Objectives
29 CFR 1910.95

Distinguish between sound and noise

Discuss types of hearing loss

Become familiar with types of noise measuring equipment

Understand the requirements of 29 CFR 1910.95
Sound Versus Noise

Sound is a pressure change detectable by the
human ear.


Pitch/frequency ranges between 20 to 20,000 Hertz
(cycles/sec)

Volume ranges between 0 to 140 dB
Noise is a type of sound.

Generally described as undesirable or unwanted sound
Types of Hearing Loss


Middle ear hearing loss results from lack of conduction.

Impacted wax

Broken ear drum
Inner ear hearing loss results from lack of neural connections.

Naturally due to aging

Loud noises

Disease
Occupational Noise Loss
Cannot
be treated or
corrected medically
Initially affects high frequencies
Progresses to lower frequencies
Threshold Shift

Temporary Threshold Shift (TTS)


Hearing returns to normal after noise exposure
Permanent Threshold Shift (PTS)

Repeated noise exposure without a return
to normal

OSHA Standard Threshold Shift (STS)

> 10 dB average loss of hearing ability at 2000, 3000, & 4000 Hz in
either ear
Non-Auditory Effects of
Noise

Affects cardiovascular & nervous systems

Interferes with speech and concentration

Causes annoyance, stress, and fatigue

Reduces work efficiency

Lowers morale

Masks warning sounds
Noise Measuring
Equipment

Sound level meters


Basic instrument to measure
sound pressure variations in air
Noise dosimeter

Combines sound pressure
and time for employee
exposure monitoring
Permissible Exposure Limits 1910.95(b)

No employee can be exposed above the permissible
exposure limit (PEL) w/o hearing protection.

OSHA PEL = 90 dBA for a 8-hour time-weighted average (TWA)

Feasible administrative or engineering controls are required.

Hearing protection provided and used to reduce sound to
within levels of Table G -16.
Table G-16 - Permissible Noise Exposures
Duration per day, hours
Sound level dBA slow response
8
90
6
92
4
95
3
97
2
100
1½
102
1
105
½
110
¼ or less
115
Footnote(1) When the daily noise exposure is composed of two or more periods of noise exposure of different levels,
their combined effect should be considered, rather than the individual effect of each. If the sum of the following
fractions: C(1)/T(1) + C(2)/T(2) C(n)/T(n) exceeds unity, then, the mixed exposure should be considered to exceed
the limit value. Cn indicates the total time of exposure at a specified noise level, and Tn indicates the total time of
exposure permitted at that level. Exposure to impulsive or impact noise should not exceed 140 dB peak sound
pressure level.
90 dBA PEL?
 90
1910.95(c)-(d)
dBA PEL (early 1970s) not
protective enough
 Recommended TLV = 85 dBA for 8
hrs is better
Noise Action Level

OSHA Action Level (AL) = 85 dBA for a 8-hour TWA


1910.95(c)-(d)
Determined without regard to hearing protector
reduction
Hearing Conservation Program (HCP) required at this level

Audiometric testing
 Baseline
& Annual Tests
A
qualified person performs the hearing test (e.g.,
audiometric tech, audiologist).
 Compare
annual test to baseline test to check for STS
Example of Audiogram
STS Notification

1910.95(g)
Recall standard threshold shift definition:

> 10 dB avg. loss @ 2000, 3000 & 4000 Hz

Employer may retest within 30 days to verify the
STS.

Employer shall notify the employee of the STS in
writing within 21 days.
STS Requirements

1910.95(g)
If STS is work-related:

Employee is fitted for hearing protection and trained

Refitted and retrained if already wearing hearing protection

Referred for audiological or otological exam, if necessary.
Hearing Protectors

Must be available to “action level” employees

Must be required for those employees:
1910.95(i)

Exposed at or above 90 dbA

Exposed at or above 85 dbA (without an audiometric baseline)

Who have an STS
Hearing Protectors

Provided at no cost to the
employee

Selected from a variety of
types and brands

Properly fitted
1910.95(i)
Noise Reduction Rating (NRR)
Appendix B

Laboratory-based reduction in decibels that the hearing
protector will provide.

NRR specified on hearing protector packages.

NRR example for A-weighted exposure data


Estimated exposure (dBA) = TWA (dBA) - (NRR - 7)/2
3M Fit Test System – example of Field Attenuation Estimation
System (FAES); use the term Personal Attenuation Rating (PAR)
Some research, particularly in Europe,
suggest links between hazardous noise
and diabetes, arthritis and
cardiovascular ailments.
Carbon Monoxide

Chemical asphyxiant
 CO
binds to hemoglobin forming
carboxyhemoglobin (COHb).
 Hemoglobin
has affinity for CO 240X greater
than that for oxygen.
 COHb
decreases oxygen saturation and shifts
the O2 hemoglobin dissociation curve to the left.
 COHb
 At
levels of 6% may cause impairment.
40-60%, alterations in mental status and
death may occur.
Silica
29 CFR 1910.1000
Table Z - 3

Basic component of soil, sand, granite, and many other
minerals

Exposure only when crystalline silica particles are in the air

If materials containing silica do not generate dust, there is little
chance of inhaling the silica

29 CFR 1910.1000 Table Z-3

OSHA PEL (mg/m³) = (10 mg/m³)/(2+% respirable quartz)
Lead – 29 CFR 1910.1025/1926.62

In bloodstream, lead is bound to red blood cells.
 Distributed
to soft tissue (liver, kidney, brain,
 Eventually
deposits in the bone
muscle)
 Half-life
of 10-30 years (bone)
Asbestos
1910.1001
1926.1101

Airborne fibers range in size from 0.1 to 10 µm in
length.

ACM: “asbestos-containing material,” any
material containing >1% asbestos.

PACM: “presumed asbestos-containing material”
– thermal system insulation and surfacing
material found in buildings constructed
no later than 1980.
Hierarchy of Protection

Engineering

Mechanical ventilation (e.g., draw bad air
away from BZ)



Work practice/administrative controls

Equipment

Housekeeping

Hygiene facilities
Employee information and training
PPE (last because it puts onus on employees)

Respiratory protection

Protective work clothing