PPE Guides & FAQ

While the KN95 standard requires a particulate filter efficiency that is comparable to the N95 standard for respiratory protection, the quality of KN95s available for retail has been less consistent. The National Personal Protective Technology Laboratory at NIOSH published results of filtration efficiency tests on KN95s which demonstrated the inconsistent performance of many KN95 masks available for purchase. This distinction also factors into the sale of masks by retailers - see Amazon's posted note on KN95s.

The respirator resources hub includes N95 respirators which are similar in style and fit to KN95 masks. For more information on types of respirators, see the NIOSH poster on types of respiratory protection.

These types of masks are not guaranteed to be effective against airborne viruses, and they are not rated for their ability to filter viral respiratory pathogens. Consider ASTM Level 3 surgical masks, which meet the strictest rating for surgical masks. ASTM International sets the standards for medical facemasks used by the United States Food and Drug Administration. Level 3 rating corresponds to the highest bacterial filtration efficiency, resistance to simulated body fluids, and particulate matter filtration. 

As noted in this state public health primer, while these masks protect the user "against fluids, microorganisms, and particulates at the level to which the mask is rated ... these masks do not provide protection against airborne diseases." Surgical masks and cloth face masks are not rated for protection against airborne viruses. Bacterial filtration efficiency does not equate to viral or particulate filtration efficiency because bacteria are much larger than viruses. 

For a quick comparison between surgical masks and N95 respirators, see this NIOSH graphic illustrating the differences.

When worn appropriately, valved/vented respirators protect the wearer. They do not necessarily protect the people around them.

In all the valved respirators listed on this website, the valve’s airflow is one-way and opens only to vent the user’s exhaled breath. There is no guarantee that a valved respirator filters the wearer’s exhaled breath. This reduces source control of airborne and droplet-borne respiratory viruses. 

Some manufacturers of particulate respirators, especially elastomerics, produce filter pieces which fit over the exhalation valve. These filter pieces sometimes must be ordered separately from the respirator itself. When these are unavailable, an ASTM Level 3 surgical mask can be worn on the outside of the respirator over the exhalation valve in an effort to enhance source control of respiratory pathogens. We reiterate that this is not official guidance and that this practice has been implemented as a contingency plan.

As for comfort, we believe this depends on your preferences. If you have never worn an N95, they are relatively easy to acquire. Some people find N95 masks more comfortable than surgical or cloth masks because many types of N95s use two bands that fit around the head instead of ear loops.

Most of the equipment listed in our hub is available at online retailers and regularly in stock. Many of these respirators are available in bulk packs that cost less than $20 USD.

Regarding difficulty, we trust that individuals who have never worn a respirator can learn to wear one with confidence with the right information. Our aim is to make this information easily accessible and to link to free, high quality resources from an unofficial central hub.

The National Institute for Occupational Safety and Health (NIOSH) is the federal agency tasked with vetting and approving particulate respirators used in US workplaces. For more information on how respirators are approved by NIOSH and how to identify counterfeit N95s, see this NIOSH publication.