New NIOSH Bulletin Explains How to Sample and Test Stockpiled Respirators
Suggested steps include pulling 40 units at random from each production lot, running three pass/fail lab tests and checking storage conditions when units fail.
- By Danielle Naidu
- Nov 09, 2026
Respirator stockpile managers can use a technique called lot quality assurance sampling to choose units for lab testing, according to a Nov. 5 Science Bulletin from the National Institute for Occupational Safety and Health (NIOSH). Makers often recommend shelf-life limits and storage conditions because respirator materials break down with age. Outside those limits, makers cannot promise the expected protection, the agency said.
Where no sampling expert is available, NIOSH suggests following its stockpile study model, which draws 40 respirators at random per production lot from a mix of pallets, boxes and cases where practical. Every pallet, case, box and unit should get a visual check during collection, with findings recorded to spot trends. Warning signs include heavy dust, light exposure, nearby chemicals and crushed packaging or units.
Third-party test labs are an excellent option, NIOSH said, as long as their accreditation covers filter efficiency along with inhalation and exhalation resistance. Each test follows a NIOSH Standard Test Procedure for N95 filtering facepiece respirators.
Both resistance tests run at 85 liters per minute. Exhalation passes under 25 mm H2O column, and inhalation passes under 35 mm H2O column. Filter efficiency passes at 5.0% particulate penetration or less, and labs must run it last because it uses a salt compound.
Newly bought units of the identical model should be tested alongside the stored ones as reference units, which add confidence that any failures in stored units trace to long-term storage.
If stored units fail, NIOSH advises reviewing inspection notes for storage problems the failed units share, confirming that humidity and temperature stayed within the manufacturer's recommended limits and correcting any poor storage. Units that fail despite proper storage and an unexpired shelf life should be reported to NIOSH at [email protected] and to the manufacturer. Passing tests does not make respirators NIOSH Approved once their shelf life has ended, the agency noted.
About the Author
Danielle Naidu is assistant editor for Occupational Health & Safety and Environmental Protection Online.