Do Masks Really Work in India’s Air Pollution?

Every year when winter rolls around, a billion people in India are left breathing toxic, polluted air when on the streets. Be it in Delhi, Mumbai, Kolkata or Hyderabad, everyone is forced to become experts in a complicated scientific question to cope with the pollution: Do air pollution masks work?

I’ve heard doubts from smart, skeptical people all across India on this question. There’s little real data out there showing whether pollution masks work, and even less information about the brands most commonly found in India. With the help of Smart Air nerd Dhariyash, who traveled down to a pollution mask lab in Mumbai, I’ll answer those doubts!

1. “There’s no way for pollution masks to capture the really small particles.”

The skeptic case: 

The most dangerous particles are the smallest particles, and levels of these are dangerously high across India. But masks are so thin! How could they possibly get those smallest particles?

The scientific pollution mask test:

Researchers from the University of Edinburgh tested different common masks by running a diesel generator (to mimic car exhaust) and piping the exhaust through different masks. They used a particle counter to see how many particles made it through the mask. This is a great benchmark for pollution in India, data shows that one of the main sources of air pollution is diesel generators (check out this report on Bangalore’s air pollution).

Here’s my super scientific rendering of the setup:

One important detail: the particle counter they used measures down to .007 microns. We’re talking about truly tiny particles here!

First, they tried a simple cotton scarf. Sometimes I see bikers in India wearing these.

can cotton handkerchiefs remove air pollution in India cities

Not great, 28% of particles blocked.

Next they tried a cheap surgical mask like the ones used in most of India’s hospitals:

surgical mask effectiveness at removing PM2.5 and air pollution

Surprisingly good! (Fit tests generally show lower results–see below–but still a lot higher than most people’s intuition.)

Next they tried several bike masks.

cycling masks in India removing air pollution PM2.5

Most were around 80%.

Then they tried several cheap 3M masks.

They all scored over 95%. Pretty good!

Conclusion: Masks capture even very small particles.

2. “OK, they capture the small particles, but when you wear them, all the air just leaks in the side.” 

The skeptic case: 

In theory, masks can catch the really small particles, but those tests aren’t on real faces! When you actually wear them, you can’t get a good enough fit, so they’re basically useless. What’s more, they’ve probably been made to fit foreign, not Indian faces!

The scientific test:

This question is tougher to answer because you have to measure the mask while you’re actually wearing it. For that, you need a US$10,000 fit-test machine. Fortunately, I begged and begged a mask company in Mumbai until they let me use their lab.

We tested a whole range of common masks you can pick up in India – including some of the most expensive, the cheapest as well as the most common. They ranged from cotton surgical masks to N90 (equivalent FFP1), to N95 (equivalent FFP2) to N99 (equivalent FFP3). We covered brands including 3M masks, Vogmask, Honeywell and Venus. Here’s the setup and the masks we tested:

India face mask comparison review including N95 (FFP2), N90 (FFP1) and N99 (FFP3) and 3M, Vogmask, Honeywell brand

And here’s how the machine works:

Dhariyash fit test air pollution mask Mumbai India

The blue tube is sampling air outside the mask, while the white tube is sampling air from inside the mask (more details on the methods here). 

Here are the results.

The 3M and Venus masks performed best. The cotton mask and surgical masks performed worst. Surprisingly, some of the big-name brands were some of the worst – the Honeywell FF2100 and Vogmask N99CV both captured less than 90% of pollutants,

How Well Do Masks Work for the Broader Population?

It’s important to make clear: masks that fit well on Dhariyash’s face might not fit other people’s faces well. However, there is evidence from a broader population that masks fit most people well. A scientific study of 3M masks on 22 Chinese people found a median fit score of 99.5%–essentially the same as the top results from Dhariyash. Results were also nearly identical in our earlier mask tests in Beijing.

Best Mask For The Price

Best yet, the data shows effective masks don’t cost a lot of money.

Cost comparison for India face masks Vogmask and Honeywell expensive. 3M and Venus cheap.

Surprisingly, the most expensive mask we tested – the Vogmask N99CV – was one of the worst performing masks.

Based on these results, we’re now shipping the Venus N99 masks through our online store.

Bike Pollution Mask India

Are Kids’ Pollution Masks Effective?

Two youngsters from Mumbai helped us test Honeywell masks for kids. Learn more about how well kids’ pollution masks work at filtering air pollution »

Kids air pollution mask fit test

Exception: Gas Pollutants

Masks are great, but note that these are tests on particulate pollution (including PM2.5). Most commercially available masks don’t target gas pollutants like NO2 and O3, so masks are not giving 100% protection.

3. Is there a documented health benefit of wearing a mask?

This is probably the hardest question to answer. However, there are two solid studies that have randomly assigned people in Beijing to wear masks or not and measured their heart rate and blood pressure (12).

While wearing masks, people had lower blood pressure and better-regulated heart rates.

Pollution mask health blood pressure smog

We’re yet to see any tests like this done in Delhi or other cities in India, but we’re pretty certain the results would be the same.

Bottom Line: Pollution Masks

Masks capture even the smallest particles—even while people are wearing them (on faces in India too!) — and they have documented health benefits. That should be enough to satisfy even the skeptics!

Smart Air


Along with wearing masks, air purifiers with HEPA filters are also one of the best ways to stay safe from a variety of pollutants in our air including viruses and dangerous PM2.5. A recent CDC study confirmed significantly lower COVID-19 infection rates in schools that used HEPA air purifiers. HEPA filters can significantly lower the risk of a variety of deadly diseases including diabetes, heart disease, cancer, and high blood pressure.

Read More: Four Steps to Choosing the Best Air Purifier

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11 thoughts on “Do Masks Really Work in India’s Air Pollution?”

  1. This time is really dangours for all of us.
    Thanks for the sharing Excellent information on your blog.
    Its really Useful for everyone.

  2. Hi, thank you for the important information.
    I wonder whether masks above listed are disposable or not?
    For example, we assume I have a surgical or N95 mask. How long can I use it?
    Is there any study showing performance chancing of a mask according to use time?
    Thank you for your reply.

  3. Hi Paddy – why cant I see the Venus N99 mask on the comparator graph for cost effectiveness? Thanks, Meenakshi

    • Hi Meenakshi! The Venus N99 is called the “Venus V-430 5LV” in the graphs. It got a a fit test effectiveness rating of 99.4%!

  4. A question/ concern I’ve long had with the PortaCount testing protocol, is what impact does a real-world, moving, body-in-motion, environment have on the test. As compared to walking or cycling down a busy polluted street with outdoor air currents, testing a still body in an office room might or might not produce the same results. Hopefully we’ll see a testing system from PortaCount or other perhaps university research project, explore this matter. It may be quite needed. Uppermost in my mind are the millions of cyclists and motorbike riders using all variety of masks, assuming they have effective protection in those strong air currents.

  5. Are these studies published in a reputed paper or journal? This will make these findings much more useful.

    • Hi Dhruv, they haven’t been published in any journals. You’re right, that getting them in papers would help in getting this information out to more people! If you know of any journals that would be willing to publish the data and information, send us an email at [email protected] and we’ll work on it!


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