How Effective Are Kid’s Masks at Filtering Air Pollution?

As cities like Delhi, Beijing and Manila face toxic levels of air pollution, people are rushing to find effective pollution masks, particularly kid’s masks.

Kid's masks in Delhi

But there’s a problem. Children’s faces are different from adults’. Add to that, children are constantly growing, meaning that the mask that fit last year might not fit this year.

Kid’s Mask Fit Test

To help worried parents, we ran open-source fit tests of with two children in Mumbai. We tested the small size of the Honeywell H950V mask, which is designed for kids.

Honeywell H950V kid's masks

Two young volunteers helped test the kid’s masks: Pallavi (8 years old) and Vijay (10 years old).

India kid's masks test effectiveness

How the kid’s mask fit test works

We know that masks are highly effective at capturing PM2.5 particles, even down to .007 microns.

PM2.5 pollution particle size in mask


But showing that masks filter particles isn’t enough. We need to know whether they work when children are actually wearing them. This is a pressing question because most masks are made (and tested) on adults, who have larger faces.

The fit test measures effectiveness while a real person is wearing the mask by using the white tube to sample air inside the mask. Meanwhile, the blue tube is sampling air just outside the mask.

Mask fit test India N99 air pollution mask

The TSI PortaCount detects particles down to .01 microns—far smaller than the oft-mentioned 2.5 microns. Then the machine uses this to estimate the percentage of particles going through the mask (as opposed to leaking in around the sides).

TSI PortaCount mask effectiveness test


Effectiveness varied 40% between the two children. This suggests that it’s important to find the best-fitting mask for each child.

India Children's Fit Test Honeywell effectiveness results

In our adult tests, pollution masks averaged 95.4% fit effectiveness. Fit effectiveness was lower on both children.

Help fitting the kid’s masks

To test whether instructing the children carefully on how to put on the mask, we ran each test again after giving each child careful help fitting the mask.

Children's mask important good fit effective

After careful fitting, Vijay’s fit score increased to 94%. However, Pallavi’s score remained at 50%.

Improve kid's masks effectiveness by Careful Fitting of mask

Thus, careful fitting seemed to help only a little bit. The low score for Pallavi may mean she needs a smaller mask.

Bottom Line: How Effective Are Kid's Masks?

Compared to wearing no mask, both children breathed significantly less pollution with the Honeywell mask. However, the 40% variation in effectiveness suggests it is worthwhile to try several masks to find a model that fits your child. 

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Help your child do a kid’s mask fit test

Don’t have access to a $10,000 TSI mask fit-testing machine? You can follow the simple steps of a poor man’s fit test for free with your child.

Air pollution mask poor man's easy fit test

Three More Things You Should Know About Masks

We have more data! Read more about the results of:

  1. Open-data fit tests of 18 masks available in India.
  2. How long do masks last? Just one day? We ran a longevity test of new masks versus masks that have been used for several weeks.
  3. Do masks capture really tiny particles? Is there any documented evidence that masks have real health benefits? Here’s what the empirical data on masks says.


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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