Airborne Contaminants
Chapter 296-841, WAC
|
Effective
Date: 04/01/07 |
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| WAC
296-841-200
Evaluate and control employee exposures |
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WAC 296-841-20003
Protect employees from
potentially hazardous exposure while you perform your exposure
evaluation, using all available resources to determine adequate
protective measures.
 |
Note:
Resources include product labels, material
safety data sheets (MSDSs), manufacturer recommendations,
and industry protocols. |
WAC 296-841-20005
Exposure evaluations
You must
(1) Conduct an exposure evaluation to determine
or reasonably estimate whether an employee is or could be exposed
to either of the following:
- An airborne contaminant above a permissible
exposure limit (PEL) listed in Table
3;
OR
- Other airborne hazards, such as biological
hazards.
|
Note:
- When evaluating air contaminants, keep
in mind that oxygen deficient conditions may also occur
due to:
– Processes such as fermentation,
decomposition of organic matter, or combustion of
fossil fuels
– Displacement by another gas
such as nitrogen or carbon dioxide
- Rules for specific substances may contain
additional requirements for determining employee exposure
- Samples from a representative group
of employees may be used for other employees performing
the same work activities, when the duration and level
of exposure are similar.
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(2) Conclude that an atmosphere is immediately
dangerous to life or health (IDLH) when you cannot determine or
reasonably estimate employee exposure.
(3) Do all of the following when you perform
your evaluation:
(a) Determine the form of the airborne
contaminant, such as dust, mist, gas, or biological agent.
(b) Make sure you do not use the amount
of protection provided to employees by respirators as a factor
in determining whether employees are exposed to an airborne
hazard.
(c) Make sure any air monitoring results
used to determine employee exposures are based on personal air
samples taken from, or representative of, the employee’s
breathing zone.
- You may use area sampling to screen for
the presence of an airborne contaminant; however, results
from area sampling cannot be used if they do not adequately
represent exposure of affected employees.
(d) Include potential emergency and rescue
situations that may occur, such as equipment or power failures,
uncontrolled chemical reactions, fire, explosion, or human error.
(e) Include workplace conditions such
as work processes, types of material, exposure control methods,
work practices, and environmental conditions.
(f) Address extended work periods. For
work shifts longer than 8 hours, evaluate the continuous 8-hour
portion of the shift expected to have the highest average exposure
concentration.
(4) Use either of the following types of
documentation to conclusively demonstrate that employee exposure
cannot meet or exceed any PEL for the airborne contaminant during
any reasonably anticipated conditions:
- – Personal air samples that represent
an employee’s usual or worst-case exposure during the
entire shift.
- or
– Specific information about products,
materials, or activities that provide for an estimate of the
level of employee exposure such as material safety data sheets
(MSDSs), observations, previous air sampling results, other
measurements, calculations, or pesticide labels.
|
Note:
You should use methods of sampling and
analysis that have been validated by the laboratory performing
the analysis. |
(5) Use the following formula to evaluate
employee exposure to 2 or more substances that have additive health
effects:
| The symbol |
Is the . . . |
| E |
Equivalent exposure for the mixture. When the value of E
is greater than 1, an airborne hazard is present. |
| C |
Concentration of a specific airborne contaminant. |
| L |
TWA, STEL, or ceiling for that substance, from Table
3, Permissible Exposure Limits (PELs) for Airborne Contaminants |
 |
Helpful Tool:
Mixtures of Airborne Substances
Use this instruction to find out if health
effects of contaminants are additive and if added exposures
represent an airborne hazard. |
|
Note:
- When results from your exposure evaluation
indicate an airborne hazard, follow requirements in WAC
296-841-20010 through 296-841-20020
of this chapter.
- When changes occur that increase the
level of exposure to an airborne hazard, you may need
to conduct a new exposure evaluation to make sure exposure
controls and other protective measures are sufficient.
|
WAC 296-841-20010
Exposure controls
IMPORTANT:
(1) Use feasible exposure controls to reduce
employee exposure to one of the following:
- - A level below the
permissible exposure limits (PEL) in Table
3.
- - A level that removes the airborne hazard,
when no PEL is established.
- - The lowest achievable level, when exposure
cannot be reduced to below the PEL or the airborne hazard cannot
be removed.
(2) Make sure exposure controls do not create
or increase employee health hazards. For example, when ventilation
systems are installed.
- - Prevent contaminated exhaust air from either:
- Reentering the building in harmful amounts
or
- Exposing any employee to a health hazard.
- - Temper make-up air, when necessary
- - Prevent employee exposure to excessive air
velocities.
(3) Use make-up air systems that will not
interfere with the effectiveness of the exhaust air system.
- - For example, make
sure enough make-up air is provided to replace the amount of
air exhausted.
|
Note:
- Table 1 provides examples of possible
exposure controls.
|
Table 1
Examples of Possible Controls
| Preferred exposure
controls include: |
For example: |
| Using a different chemical (this is
also known as substitution) |
- Choose a chemical with a lower evaporation
rate or vapor pressure
- Choose a chemical that's not hazardous
|
| Changing a process
to decrese emissions |
- Use hand rolling or paint dipping instead
of paint spraying
- Bolt items instead of welding them
|
| Separating employees from emissions
areas and sources |
- Use control rooms
- Build an inclosure around process machinery
or other emissions sources
- Automate a process
|
| Using local
exhaust ventilation to remove emissions at or near the source |
- Install exhaust hoods or slots to capture
emissions
- Use an exhausted enclosure (like a blasting
cabinet or laboratory hood)
|
| Other exposures controls include: |
For example: |
Using general
exhaust ventilation to dilute and remove emissions in the
work area
Note:
This is not recommended for control of
highly toxic airborne contaminants such as carcinogens,
where low exposures can still present a health hazard |
- Allow natural air movement to create
an adequate airflow through an area
- Use mechanical fans
|
Limiting the amount of time employees
can spend in a contaminated area |
- Establish a contaminant-free area for
tasks such as prep work that do not need to be done in
the exposure area
|
|
Modifying work practices |
- Change the position of the employee
relative to the work so fumes, vapors, or smoke are not
directed into the employee's face
|
| Implementing an employee rotation schedule |
- Have employees alternate working in
the exposure area so that each employee gets less overall
exposure
|
WAC 296-841-20015
Respirators
- Require employees to use respirators when
airborne hazards haven’t been removed using feasible exposure
controls. For example, use respirators at any of the following
times:
– While exposure controls are being
evaluated or put in place
– When the airborbne hazard isn’t
completely removed
– When exposure controls are not
feasible.
| 
|
Reference:
See chapter 296-842 WAC, Respirators,
for respirator program requirements. |
WAC 296-841-20020
Notification
• Notify employees who are, or
may be exposed to airborne hazards, as specified in Table
2.
|
Note:
- The notification may be provided either
individually, to a group, or by posting of results in
an appropriate location that is accessible to affected
employees.
|
Table
2
Notification Requirements
| Notify employees
of |
As follows |
| Any exposure result above a permissible exposure limit
(PEL) |
Within 5 business days, after the employee's exposure
result is known to the employer |
| The corrective action taken to reduce employee exposure
to or below the PEL and
The schedule for completion of the corrective action
and any reasons why exposures cannot be lowered to below
the PEL |
Within 15 business days, after the employee's exposure
result in known to the employer |
WAC 296-841-20025
Permissible exposure limits (PELs)
Important:
The following information applies to Table
3, Exposure Limits (PELs) for Airborne Contaminants.
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