COVID-19 Fact Sheet: Workers Need Respirators

COVID-19: Workers Need Respirators

Anyone can be a source. Anyone can be a receiver.

With an N95 filtering facepiece respirator (FFR)…

…he has 1-10% inward leakage and outward leakage.

Workers need a fit-tested* respirator to prevent inhalation of infectious particles. Better respirators with higher protection factors should be used for high particle concentrations.

With a surgical mask…

…he has 50% inward leakage and outward leakage

A surgical mask may be appropriate for patients to wear as source control. It does not provide adequate protection for workers from inhalable infectious particles.

With a cloth face covering (Cloth FC)…

…he has 75% inward leakage and outward leakage.

A cloth face covering may be appropriate for the public to wear as source control, but they should limit proximity to others and time spent in an indoor space.

*N95 FFRs have an assigned protection factor of 10 (10% inward leakage) but must receive a fit factor of 100 (1% inward leakage) on an individual worker.


According to CDC, an uninfected person with no face covering can be infected if within 6 feet of an infected person for 15 minutes. The time increases to 27 minutes if both are wearing a cloth FC, and to 25,000 hours if both are wearing a fit-tested N95 FFR. The table below indicates time to infection for other combinations.


Time to Infectious Dose for Someone Not Infected with COVID-19

INWARD LEAKAGE = Percentage of particles entering the facepiece to be inhaled by a receiver

OUTWARD LEAKAGE = Percentage of particles exhaled by a source exiting the facepiece

WARNING: If respirators are required for other workplace hazards, do not stop their use. Treat COVID-19 as a new hazard that may require additional protection.