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Pollution Mask Specifications, PM2.5, N95, N99, Etc.Pollution masks come in various claimed specifications, based on government standards, which include PM2.5, N95, N99, N100, R95 ..., P95 ..., EN 143 ... and others. In this article, I will try to explain in plain English what this is all about, and organize it so you can quickly and easily decide what is of interest to you, and can forget about a lot of the rest. However, you should also understand some of the serious caveats of these standards. This section is to help you know the terminology and understand the different standards, including their limitations and shortcomings. PM is an acronym for Particular Matter, not Pollution Mask. For example, PM2.5 refers to particles in the air of size 2.5 microns or less, and PM10 refers to particles of 10 microns or less.
N95 masks filter a minimum of 95% of all airborne particles (see caveats below),
This is not the percent of PM2.5, this is the percent of all particles, such as larger pollution particles. They are actually tested against particles down to around 0.3 microns in size. (See our page on "ailments" to see some caveats about that. Basically, the amount removed is based on the total mass, not the number of particles. Since one 10 PM radius particle equals about a million 0.1 PM radius particles, and one 2.5 PM radius particle equals around 15,000 particles of 0.1 PM, and the 0.1 PM particles can be far more damaging to long term health due to their ability to enter cells and cross the blood brain barrier, the government standards are actually very questionable as regards the novice general public who follow simple standards, but this is what our political and business system has generated as a standard to date. See also what many scientists are publishing...) The most damaging particles for many people are the smallest, which can pass through cell membranes and the blood-brain barrier, for which there are no regulations against and which the N99 and other standards do not significantly address. Larger particles can irritate the lungs and cause other symptoms, but the smallest nanoparticles can get into your bloodstream and affect many different organs. The public should also keep in mind that the tests are done using air samples which might or might not apply well to the air around you in particular, which I discuss in the section about kinds of pollution. For example, diesel engines on highways emit an abundance of different kinds of invisible microscopic particles, whereas gasoline engine cars and other sources of particles predominate in other environments. These latter issues are discussed in other sections on this website. This page is mainly about the standards, but the standards should be understood to have major shortcomings. Back to the standards: The higher the N number, the more difficult it is to pass air through the filter (of a given size), including for breathing. For example, an N95 mask may be more appropriate for bicycling. Large filters are best. These N standards were set by the government of the United States of America, in particular the National Institute for Occupational Safety and Health (NIOSH). The above N numbers seem to be the most commonly stated specifications in the market. There are some other specifications, too, which I'll mention here just because you might hear about them. NIOSH also has R95, R99, and R100, as well as P95, P99, and P100. The N filters are for "Non oil resistant", because if there are oil particles suspended in the air, these can degrade the ability of the filters to remove particles. The R designation is for "oil Resistant" filters which will work for awhile with oil particles around (standard is up to 8 hours), and the P is for "oil Proof" which work even longer than the R filters when oil particles are around (standard is 40 hours of usage or 30 days of age). Most people don't need to worry about oil particles being around in significant quantities. There is also an old standard called HEPA, High Efficiency Particulate Arrestance, which is essentially N100 in that it is supposed to remove 99.97% of particulate matter.
European standards include EN 143, which has 3 subcategories:
However, just because you have a pollution mask with a rating of N95, that doesn't necessarily mean that you are filtering out 95% of the particulate matter around you. Typically, the higher the N number, the harder the filter material. One of the main problems is leakage around the mask. Many masks on the market of N95 or higher spec do not bend and contour around your face well, even with uncomfortably tight rubber bands around the ears and a metal nose clip, but even with a relatively tight fit, you can feel air going around the mask in places, which is air entirely bypassing the mask, 0% filtration. That may be an easier way for air to get in, without the resistance of the filter. This is why our masks are designed with additional soft material to conform to your face, to seal leaks. As noted, the higher the rating of the mask, the more difficult it is to breathe through the filter, so for high mask ratings, it is important to have large filters to minimize the difficulty of breathing through the mask. We provide large filter sizes for this reason.
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