Industrial Hygiene

The evaluation begins by determining whether an air-purifying respirator is appropriate for the contaminant and workplace atmosphere. Relevant factors include the contaminant's identity, physical form and concentration, oxygen level, IDLH conditions, respirator configuration, assigned protection factor, maximum use concentration, and the cartridge or filter approved for the intended use. For gas- or vapor-removing cartridges, the evaluation should also consider an appropriate NIOSH-certified end-of-service-life indicator or a change schedule based on objective information or data. A cartridge should therefore be evaluated as part of the complete respirator selection rather than in isolation.

Formaldehyde exposure can be assessed by evaluating how and where formaldehyde is used or released, employee tasks, exposure duration, ventilation, process conditions, and representative exposure-monitoring data. Personal breathing-zone sampling can be used to characterize full-shift or short-term employee exposure, while area measurements and process records may provide additional information about sources and workplace conditions. Historical exposure assessments may also use chemical-use records, ventilation information, operating data, and prior monitoring, with uncertainties and assumptions identified. The presence of formaldehyde in a workplace alone does not establish the concentration or duration of an individual employee's exposure.