N95 Pollution Masks: A Buyer’s Guide

I’m a big fan of using air pollution masks when the AQI is over 200 and the Chinese market has a lot of new competition since last January’s airpocalypse. Even in convenience stores such as 7-11 you can now find a big display of pollution masks stamped with N95, 99% or something similarly impressive on their labels. “Wow, this 5 RMB surgical mask says it’s 99% effective — plus, it’s imported from Japan!” Not so fast. Any marketing person can throw any numbers on these packages — we consumers need to dig a bit deeper and find out just where these numbers are coming from. Air pollution is such a serious issue here in China that we really need to stick with the best masks — with proven results from independent labs, not just TV advertorials and website testimonials. Here’s my advice on how to find the best mask.

What The Heck Is N95, Anyway?

We hear and read about this “N95” so much — are you sure you know what it means? Here’s a nice synopsis of what N95 certification means, from Nelson Labs, an independent testing center in the USA:

…If you are a manufacturer of respirators, one of the most important processes you must go through is to receive certification from the National Institute for Occupational Safety and Health (NIOSH). NIOSH respirator certification is necessary in order to label your respirator with one of the three “N” certification categories: N95, N99 or N100. N95 respirators are used to filter contaminants such as dust, fumes, mists, as well as microbial agents including tuberculosis bacteria and flu virus. They are certified to filter greater than or equal to 95 percent of all challenged particles free of oil and greater than 0.3 microns in size. N99 respirators filter greater than or equal to 99 percent…

Let’s say that again: a mask rated N95 filters out more than 95% of particles (PM) larger than 0.3 microns — that’s much smaller even than PM2.5 microns. This is a good thing, since most of air pollution’s bad health effects are caused by particles 2.5 microns and smaller (the width of a human hair is 70 microns). These masks really work.

But here is an important point: almost every mask you see on the Chinese market, except for 3M, isn’t officially certified N95. Only the USA’s governmental agency NIOSH gives out the N95 certification, and if it’s not on their lists here or database here, then it’s notcertified N95. But just because it’s not on this list does not mean it’s a crappy mask — a handful of masks not on this official list actually have proven 95% effectiveness from testing. It’s actually very expensive and difficult to jump through all those government hoops for official NIOSH certification. N95 is more for industrial worker safety, and mega-companies such as 3M can easily afford those tests, while smaller consumer start-ups can barely afford local testing, much less certification. Other countries have their own ratings which you may see on packages, such as the European EN149 FFP2 or Chinese YY-0469, both equivalent to N95.

Not All Tests Are Created Equal

My second major point in this article is that there are two important but extremely different tests of a masks’ effectiveness. The first tests the material itself, pushing a microscopic chemicals such as latex through a swatch of the fabric and seeing what percentage make it to the other side. These are called particle challenge tests. Quite a few of the most popular masks have results way over 99%. Vogmask gets 99.978%; Totobobo 99.85%; Lvdun 绿盾PM2.5口罩 99.45% … Those are incredible numbers, yes?

Yes, they are — but the problem is this: this test means nothing in the real world. You could do a particle test on a rock and get 100% efficiency, but you’re not going to wear it on your face. The best fabric in the world is totally useless if the mask itself doesn’t fit your face well, with air leaking all around it. This is why it’s far more important to make sure your mask has fit test results. During these tests, an actual human being is wearing the mask, and special sensors are sticking out of it, measuring efficiency over a span of 15 minutes. There are two types of fit tests: qualitative, which are personal impressions of a masks’ fit; and quantitative, the hard data showing efficiency at filtering out PM2.5, PM0.3 and even smaller particles. Of these two, the quantitative data is far more useful for us. A person could love the comfort and give the quantitative results an A+, but if the hard data only shows 50% filtration, then who cares how comfortable it is?

Why is this important? Because a bunch of mask companies are bragging about being 99% effective — but they’re only talking about their particle challenge results, not fit test results. This is the major reason why I am not thrilled with Respro masks, which have impressive 99% results on particle challenge but are only 88% effective on their fit test results. Why buy a mask like this when there are a handful of other masks which filter better (and also are cheaper)? For the same reason, I am not a big fan of the newly popular Chinese branded mask, Lvdun 绿盾PM2.5口罩, available at 7-11. Their particle challenge results are just as impressive as the rest, again far above 99%, so their filter fabric is excellent. But I don’t see a fit test report on their website or their Weibo. Plus this filter is not the entire mask at all, it’s a smallish rectangle which you insert inside the fabric of the mask. I personally tried this for a few days and noticed air leakage and street smells, so I highly doubt they could get a fit test of 95% or above. Maybe they can, but again, given the gravity of our air pollution, why buy any mask that doesn’t have a fit test report over 95% when so many others do?

In the same vein, there are a bunch of surgical masks and other masks online and in stores bragging about 95% or 99% on their shiny packages, many claiming to be from Korea and Japan. But again, there’s almost no way any of these throwaway surgical masks are truly 95-99% effective in the real world, as it’s obvious there’s massive air leaking around most of these. OK, they are better than a simple cotton mask, as one study showed surgical mask effectiveness at 80%, compared to 28% with a simple cotton handkerchief. But if you’re buying cheap disposables anyway, why not stick with 3M, which are proven much more effective?

Fit Testing (Quantitative)

So Which Have These Fit Test Reports?

There are four brands that I am aware of which have both particle challenge results over 99% and quantitative fit test results over 95% for PM2.5:

I personally have used all of these and feel that all are good choices. I continue to use them on different occasions, and I have no strong preference for any of them. I have them stashed at work, at home, in my briefcase and in my bike saddle bags.

So take your pick! If you don’t like the fit of one, try another. Experiment, and leave your own personal feedback below in the comments section. An educated consumer is always a better consumer.

If you want more information on masks, you can read a few key earlier articles (herehere and here) as well as wander around my air pollution archives.

What About Kid Sizes?

As of this month there are finally good options for kids. The Vogmask company now has two versions that fit a kid’s smaller face; they are first on the market to pass fit test results on children, showing over 95% effectiveness on a 9 year old boy. Totobobo also has a new model which you can custom mold to faces using hot water, which you can trim down to a child’s face. This custom molding may lead to better fit and thus higher effectiveness.

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