Respiratory Protection Program Practice Test

End-of-service life is determined by the cartridge or filter manufacturer. The typical indicator is the ESL—end-of-service life—or the specific protection-life guidance provided by the maker. When the ESL is reached, or when the manufacturer’s guidance says protection can no longer be guaranteed under the given conditions, the cartridge or filter must be replaced. If a product doesn’t provide an ESL, you still follow the manufacturer’s instructions for replacement, which may be based on time in service, exposure levels, breakthrough monitoring, or other performance criteria.

Color change in the material and smelling odors are not reliable signs of when protection has failed; many filters won’t visibly change color, and odors can be misleading or absent even when breakthrough is occurring. The fact that a cartridge is out of stock is not an indication of its end-of-service life.

In short, rely on the manufacturer’s ESL or replacement guidance as the standard indicator for changing cartridges or filters.