Exposure Assessment
When? What? How Much?

Employers must characterize the nature and magnitude of employee exposures to respiratory hazards before selecting respiratory protection equipment. Paragraph 29 CFR 1910.134(d)(1)(iii) requires the employer to identify and evaluate the respiratory hazard(s) in the workplace. Employers must make a "reasonable estimate" of the employee exposures anticipated to occur as a result of those hazards, including those likely to be encountered in reasonably foreseeable emergency situations, and must also identify the physical state and chemical form of such contaminant(s). The final rule does not specify how the employer is to make reasonable estimates of employee exposures for the purposes of selecting respirators.

When must an employer conduct an exposure assessment?
When you expose your employees to a respiratory hazard and/or require them to wear respirators. Examples of when you should consider assessments may include but are not limited to:
What is the identity and nature of the airborne contaminant?
Specific characteristics of the airborne hazard must be established in order to select an appropriate respirator.
How much employee exposure is there in the workplace?
The final rule permits employers to use many approaches for estimating worker exposures to respiratory hazards.