Dust mask ratings
N, R, and P are the three designations by NIOSH regarding the ability of a particle filter to resist oil.
- N means “not resistant to oil.” These masks should not be used if there is oil mist in the air.
- R means “somewhat resistant to oil.” These masks should be used no longer than eight hours in a work area containing oil mist.
- P means “strongly resistant to oil.” These masks last the longest in an environment containing oil mist.
The second way dust masks are rated is with one of three numbers: 95, 99, or 100. These numbers denote the efficiency of the filter.
- 95 means the mask filters at least 95% of airborne particles in a worst-case scenario.
- 99 means the mask filters at least 99% of airborne particles in a worst-case scenario.
- 100 means the mask filters at least 99.7% of airborne particles in a worst-case scenario.
The above letters and numbers are combined to offer the consumer a total of nine different options when it comes to particle masks: N-95, N-99, N-100; R-95, R-99, R-100; P-95, P-99, P-100.
Q. I have really bad pollen allergies. Will an N95 mask help me while I mow the lawn or do other outside work or cycling?
A. An N95 respirator dust mask should provide sufficient protection against most common forms of backyard pollen and allergens since these masks are designed to filter out any particles larger than 0.3 microns in diameter. However, the overall effectiveness of any dust mask depends largely on the quality of the seal. Make sure you test both the negative and positive pressure (essentially, breath in and out) to make sure dust and pollen cannot enter through the mask’s edges.
Q. I work in an office, but occasionally I have to visit the factory floor to speak with a foreman. Should I wear an N95 mask for protection?
A. Many companies have established safety protocols that determine what protective gear employees need to wear while in certain areas, which might include a NIOSH-approved N95 dust mask. If the environment also contains oil vapor or other chemicals, your employer could require a mask rated for oil resistance or a higher particulate count, such as R99 or P100. The N95 mask is a good all-around dust mask, but it isn’t necessarily the best choice for some environments.
Q. I live in an area prone to forest fires. Will an N95 mask protect me from the hazardous smoke and ash?
A. In most situations, an N95 respirator mask should provide enough protection against prolonged breathing of smoke and ash particles. It’s a fairly common recommendation from safety officials whenever a wildfire or forest fire creates thick plumes of smoke in residential areas. Sometimes retail supplies of these masks can become critically low during an emergency, so it can pay to stock up whenever possible.