(1) The employer must make sure employees are protected from potentially hazardous exposure while the employer performs an evaluation.
(2) The employer must perform the evaluation without considering the protection provided to employees by a respirator.
(3) The employer must determine the form of the hazard, such as dust, mist, gas, oxygen deficiency, or biological agent.
(4) The employer must make sure to consider:
(a) Potential emergency and rescue situations that may occur, such as equipment or power failures, uncontrolled chemical reactions, fire, explosion, or human error;
(b) Workplace conditions such as work processes, types of material, control methods, work practices and environmental conditions.
(5) The employer must determine or reasonably estimate whether any employee is or could be exposed to any of the following:
(a) Any airborne substance above a permissible exposure limit (PEL) listed in Table 3;
(b) A substance at or above the action level (AL) specified in the rule for that substance;
(c) Any other respiratory hazard.
(6) The employer must use any of the following to determine employee exposure:
(a) Information that would allow an estimate of the level of employee exposure, such as MSDSs or pesticide labels, observations, measurements or calculations;
(b) Data demonstrating that a particular product, material or activity cannot result in employee exposure at or above the AL or PEL;
(c) Personal air samples that represent an employee's usual or worst case exposure for the entire shift.
Notes: | 1. Rules for specific substances may contain additional requirements for determining employee exposure. |
| 2. Use methods of sampling and analysis that have been validated by the laboratory performing the analysis. |
| 3. 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. |
(7) The employer must consider the atmosphere to be immediately dangerous to life or health (IDLH) when the employer cannot determine or reasonably estimate employee exposure;
(8) The employer must make sure employee exposure, to 2 or more substances with additive health effects, is evaluated using this formula:
The symbol | Is the . . . |
E | Equivalent exposure for the mixture. When the value of E is greater than 1, a respiratory hazard is present. |
C | Concentration of a particular substance. |
L | TWA, STEL, or ceiling for that substance from Table 3. |