Researchers put 6 types of mask on dummy heads beside busy roads in Ho Chi Minh City. Cloth and surgical masks blocked only 25 to 60% of traffic particles. N95-type masks blocked 60 to 80%. Most of the loss came from gaps around the face.

9 pollution masks were tested on volunteers. The filter material worked, but gaps around the edges let in 3 to 68% of particles. Only 1 mask kept leaks under 10%.

105 men were fit tested for N95 masks. Not one man with a full beard passed. Only about half of clean-shaven men passed.

12 healthy men exercised to their limit with no mask, a surgical mask and an N95-type mask. The most air they could breathe fell from 131 to 99 litres a minute with the N95. This was measured at full effort, not normal riding.

After one hour wearing an N95, the hot, humid air inside the mask felt like 54°C.

Of 158 frontline health workers, 81% got new headaches from wearing N95s and other protective gear. Wearing it more than 4 hours a day made headaches much more likely.

Researchers tested used masks from 109 people. Bacteria grew on the side touching the face, and fungi built up the longer a mask was reused.

66 people with acne or rosacea wore masks 6 or more hours a day. Their skin got worse where the mask sat.

US workplace safety rules rate any half-face mask, disposable or rubber, at only 10 times protection once worn. They also ban facial hair under the seal.

3M's own data sheet: the P100 filter stops at least 99.97% of particles in a lab test. That's the filter alone, not the whole mask on a face.

In a hospital trial, 92% of people passed a fit test first time with a reusable rubber mask, about the same as N95s.

Health workers wore reusable respirators for 12 weeks. Many reported facial heat (64%), sweat (70%), skin irritation (72%) and muffled speech (76%). They were indoors, not riding in traffic.

Reusable respirators must be taken apart, washed, disinfected, rinsed and dried. Leftover disinfectant can irritate your skin.

3M's spec sheet: the 7500 rubber facepiece alone weighs about 135 g, before the filters are added.

With the right cartridges, 3M respirators remove some gases and smells. Cartridges must be changed on a schedule, or as soon as you can smell through them.

Price check, October 2026: 3M Aura N95 masks cost about US$1 to 1.30 each in boxes of 20.

Price check, October 2026: a pair of 3M 2091 P100 filters costs about US$9. Gas cartridges cost more.

Price check, October 2026: boxes of 50 surgical masks sell for roughly US$1 to 15, about US$0.10 a mask. One a day comes to about US$35 a year.

3M doesn't give a fixed filter life. You change the filters when breathing gets harder or they're damaged. Our estimate assumes one US$32 facepiece a year plus a new US$9 pair of filters each month, about US$140.

Easi Breezi filters cost US$0.35 each in packs of 10. Changing one every week comes to about US$18 a year. Riders in light traffic may go longer between changes.

H11 is a European filter grade (EN 1822) that must catch at least 95% of particles at the hardest size to stop. We also tested our own filter on a TSI 8130A filter tester: 4 samples captured 97.07 to 97.64% of fine aerosol. This is a lab test of the filter, not a street test.