Respiratory Hazards

Chapter 296-841, WAC

Effective Date: 01/01/04

Helpful Tools

Evaluate and Control Employee Exposures

WAC 296-841-200

For printing


To protect your employees from exposure to respiratory hazards in the workplace by identifying and controlling the hazards

You must

WAC 296-841-20005

Identify and evaluate respiratory hazards

WAC 296-841-20010

Control employee exposures

WAC 296-841-20015

Use respirators

WAC 296-841-20020

Notify employees

WAC 296-841-20025

Permissible exposure limits of air contaminants


WAC 296-841-20005

Identify and evaluate respiratory hazards

You must

  • Make sure employees are protected from potentially hazardous exposure while you perform your evaluation
  • Perform your evaluation without considering the protection provided to employees by a respirator
  • Determine the form of the hazard, such as dust, mist, gas, oxygen deficiency, or biological agent.
  • Make sure you consider:
    • – Potential emergency and rescue situations that may occur, such as equipment or power failures, uncontrolled chemical reactions, fire, explosion, or human error
    • – Workplace conditions such as work processes, types of material, control methods, work practices and environmental conditions.
  • Determine or reasonably estimate whether any employee is or could be exposed to any of the following:
    • – Any airborne substance above a permissible exposure limit (PEL) listed in Table 3
    • – A substance at or above the action level (AL) specified in the rule for that substance
    • – Any other respiratory hazard.
  • Use any of the following to determine employee exposure:
    • – Information that would allow an estimate of the level of employee exposure, such as MSDSs or pesticide labels, observations, measurements or calculations
    • – Data demonstrating that a particular product, material or activity can’t result in employee exposure at or above the AL or PEL
    • – Personal air samples that represent an employee’s usual or worst case exposure for the entire shift.


– Rules for specific substances may contain additional requirements for determining employee exposure.

– Use methods of sampling and analysis that have been validated by the laboratory performing the analysis.

– 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.

You must

  • Consider the atmosphere to be immediately dangerous to life or health (IDLH) when you can’t determine or reasonably estimate employee exposure
  • Make sure employee exposure, to 2 or more substances with additive health effects, is evaluated using this formula:

The symbol

Is the


Equivalent exposure for the mixture. When the value of E is greater than 1, a respiratory hazard is present.


Concentration of a substance.


TWA, STEL, or ceiling for that substance, from Table 3.

Helpful Tool

Helpful Tool:

Mixtures of Airborne Substances

You can find additional information about mixtures of airborne substances in the Resources section of this chapter.

WAC 296-841-20010

Control employee exposures


Using respirators and other PPE isn’t a substitute for the feasible controls required by this section.

You must

  • • Use feasible controls to protect employees from exposure to respiratory hazards by:
    • – Reducing employee exposure to a level that removes the respiratory hazard, such as to a level below the permissible exposure limit (PEL) in Table 3;

    • – Reducing the exposure to the lowest achievable level, when the respiratory hazard can’t be removed.


The following table gives you examples of control methods

Table 1
Examples of Possible Controls


For Example

Using a different chemical (substitution)

  • Choose a chemical with a lower evaporation rate or vapor pressure
  • Choose a chemical without hazardous ingredients

Changing a process to lessen 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

Removing emissions at or near the source (local exhaust ventilation

  • Install exhaust hoods or slots to capture emissions
  • Use an exhausted enclosure (like a blasting cabinet or laboratory hood)

Diluting and removing emissions in the work area (general exhaust ventilation)

  • Allow natural air movement to create an adequate airflow through an area
  • Use mechanical fans

Modify work practices

  • Change the position of the worker relative to the work so fumes, vapors, or smoke doesn't go into their face

Rotate employees

  • -Some specific rules prohibit the use of this control method
  • Move employees to another job that is without exposure, on a schedule to keep their total exposure below the permissible exposure limit


WAC 296-841-20015

Use respirators

You must

  • Require employees to use respiratory protection when respiratory hazards haven’t been removed using feasible controls. For example, use respirators at any of the following times:
    • – While controls are being evaluated or put in place
    • – When the respiratory hazard isn’t completely removed
    • – When controls are not feasible.



See chapter 296-842 WAC, Respirators, for respirator program requirements.

WAC 296-841-20020

Notify employees

You must

• Notify employees who are or may be exposed to respiratory hazards, as specified in Table 2.



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 can't be lowered to below the PEL

Within 15 business days, after the employee's exposure result in known to the employer

An exposure to these substances:

  • Acrylonitrile
  • Arsenic (inorganic)
  • Asbestos
  • Benzene
  • Butadine
  • Cadmium
  • Coke oven emissions
  • Cotton dust
  • 1,2-Dibromo-3-chloropropane
  • Ethylene oxide
  • Formaldehyde
  • Lead
  • Methyene chloride
  • Methylenedianiline
  • Vinyl chloride

In writing, as specified in the rule specific to the substance


WAC 296-841-20025

Permissible exposure limits of air contaminants


The following information applies to Table 3, Exposure Limits for Air Contaminants.

  • Exposure needs to be determined from personal air samples taken in the breathing zone OR from monitoring representative of the employee’s breathing zone.
  • Ppm refers to parts of vapor or gas per million parts of air by volume, at 25° C and 760 mm Hg pressure.
  • (Mg/m3) refers to milligrams of substance per cubic meter of air.
  • For a metal that is measured as the metal itself, only the CAS number for the metal is given. The CAS numbers for individual compounds of the metal aren’t provided. For more information about CAS registry numbers see the website:
  • Time weighted averages (TWA8) represent the maximum allowed average exposure for any 8-hour time period. For work periods longer than 8-hours the TWA8 needs to be determined using the 8 continuous hours with the highest average concentration.
  • Short-term exposure limits (STEL) represent maximum allowed average exposure for any 15-minute period, unless another time period is noted in Table 3.
  • The ceiling represents the maximum allowed exposure for the shortest time period that can feasibly be measured.
  • An “X” in the “skin” column indicates the substance can be absorbed through the skin, either by airborne or direct contact.
  • Additional requirements for the use of gloves, coveralls, goggles, and other personal protective equipment can be found in WAC 296-800-160.
  • The respirable fraction of particulate is measured by sampling with a size-selector having the following characteristics:
  • Mean aerodynamic diameter in micrometers

    Percent passing the selector



















    Table 3
    Exposure Limits for Air Contaminants Table

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