To put it simply, the N/R/P series is the American standard, that is, the N, R, and P levels of 3M brand masks represent the standards of different levels and types of 3M brand masks.

N means "Non-oil" (not resistant to oily particles). Usually non-oily particulate matter refers to coal dust, cement dust, acid mist, microorganisms, etc. In the current raging haze pollution, suspended particles are mostly non-oily. Oily particulate matter refers to oil smoke, oil mist, asphalt smoke, etc.

R refers to "Resistant to Oil" (restricted oil-resistant particles).

P refers to "Oilprotective" (anti-oil particles), which means it can filter both oily and non-oily particles.

Extended information:

Use time of each grade of 3M brand mask:

When used to protect oily particles, the cumulative use time of R type at one time shall not exceed 8 hours;

The cumulative usage time of category P does not exceed 40 hours, or the cumulative usage time reaches 30 days from the beginning, whichever arrives earlier.

Notes:

1. 3M protective masks cannot be washed, because washing will destroy the mask filter material and mask structure; if they are not contaminated or damaged, and meet the hygienic requirements , you can consider using it again.

2. N95 masks are not product trademarks or brands. N95 is the lowest level of filtration efficiency required by NIOSH (National Institute for Occupational Safety and Health) in the United States for occupational particulate respirators in the United States. It refers to the standard stipulations. Under the test conditions, the filtration efficiency of non-oily particles (such as dust, paint mist, acid mist, microorganisms, etc.) is at least 95.

Reference material: People's Daily Online - How to choose a "haze" protective mask