{"id":9714,"date":"2026-03-09T11:38:03","date_gmt":"2026-03-09T03:38:03","guid":{"rendered":"https:\/\/smartairfilters.com\/?p=9714"},"modified":"2026-03-09T11:38:04","modified_gmt":"2026-03-09T03:38:04","slug":"n95-mask-surgical-covid-19","status":"publish","type":"post","link":"https:\/\/smartairfilters.com\/en\/blog\/n95-mask-surgical-covid-19\/","title":{"rendered":"N95 Masks vs. Surgical Masks: Which Is Better For COVID-19?"},"content":{"rendered":"

Scientists have actually randomized people to wear N95 or regular surgical masks, then tracked how many people got infected with viruses similar to COVID-19 such as the flu. This data can tell us whether N95 or surgical masks are more effective at preventing infection of respiratory viruses including COVID-19. The results surprised me.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n
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<\/h4>\n

COVID-19 & Mask Livestream<\/h4>\n

Wondering whether masks work to protect you against COVID-19? Check out our livestream recap covering all the info here<\/a>!<\/p>\n<\/div>\n\n\n\n

People\u2019s Intuitions About N95 Masks and COVID-19<\/h3>\n\n\n\n

The results are surprising because I\u2019ve seen several people claim that we need<\/strong> N95 masks to stop the coronavirus. They say surgical masks just won\u2019t cut it when it comes to COVID.<\/p>\n\n\n

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\"Coronavirus<\/figure><\/div>\n\n\n

Similarly, a doctor interviewed on CNN<\/a> said that masks don’t work.<\/p>\n\n\n

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\"Coronavirus<\/figure><\/div>\n\n\n

And to be honest, that\u2019s my intuition too. N95 masks fit a lot tighter than surgical masks, and they capture a higher percentage of particles<\/a><\/span>. They\u2019re what I wear in Delhi and Beijing to protect against air pollution.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

<\/h3>\n\n\n\n

The Surgical Mask vs. N95 Mask Test<\/h3>\n\n\n\n

Scientists tested this question by randomly assigning over 2,000 nurses to wear N95<\/a><\/span> or surgical masks. Then they tracked how many of them caught the flu.<\/p>\n\n\n

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\"Surgical<\/figure><\/div>\n\n\n

I polled people on Twitter<\/a><\/span> to see what people guessed. A majority (68%) guessed N95, so I\u2019m not alone in my intuition.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

But when the data came back, it turned out that rates of infection were the same!<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

Differences weren\u2019t significant, although surgical mask users actually had slightly lower infection rates.<\/p>\n\n\n

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\"\"<\/figure><\/div>\n\n\n

OK, Maybe That Study Was a Fluke<\/h3>\n\n\n\n

Data can be flukey. That\u2019s just one study. But it\u2019s not the only one.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

Researchers in Canada randomly assigned 446 nurses<\/a><\/span> to wear N95 or surgical masks during a few months of cold and flu seasons (September to December). Then they tracked how many got the flu or a cold.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

Again, no significant difference! Both masks performed just as well at preventing the transmission of the viruses. About 9% percent of nurses wearing surgical masks got sick versus 10% wearing N95 masks.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

Entirely Reasonable Skepticism<\/h3>\n\n\n\n

At this point, there must be at least a few savvy readers thinking, \u201caha!\u201d<\/p>\n\n\n

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\"\"<\/figure><\/div>\n\n\n

I know what\u2019s going on! These studies didn\u2019t have a control group, so we don\u2019t know whether the masks worked. If they both don\u2019t work, then of course there\u2019s no significant difference!<\/p>\n\n\n\n

That\u2019s a great question. It\u2019s just hard to test because, what are we going to do? Assign nurses to NOT wear masks? That seems irresponsible.<\/p>\n\n\n\n

What we need is some situation where people face infection but don\u2019t normally wear masks. It turns out, scientists found just such a place:<\/p>\n\n\n

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\"\"<\/figure><\/div>\n\n\n

Home!<\/p>\n\n\n\n

The No-Mask Test on Viruses<\/h3>\n\n\n\n

Researchers in Australia studied parents taking care of their children<\/a><\/span>, who were sick with the flu.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

Because people often don\u2019t<\/strong> wear masks at home (even around sick people), researchers could defensibly randomly assign people to wear masks or not. They randomly assigned parents to wear no mask, a surgical mask, or an N95 mask like the one I\u2019m wearing here.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

Then they tracked how many parents got the flu.<\/p>\n\n\n\n

About 16% of parents not wearing a mask got sick, compared to 8% in the surgical and N95 mask groups (called \u201cP2\u201d masks in Australia). Thus, masks seemed to work! But again, surgical masks were just as effective as N95 masks. And the effect size was fairly large\u2014half the infection rate.<\/p>\n\n\n

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\"Surgical<\/figure><\/div>\n\n\n

Perhaps not surprisingly, the masks only worked for people who actually wore them. There was no benefit among people who often forgot or just gave up on wearing the mask.<\/p>\n\n\n\n

Maybe this <\/strong>study was a fluke too? A different group of researchers tried the same test in German homes<\/a> and found similar results.<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

How Could Surgical Masks Work as Well as N95 Masks at Capturing Viruses & COVID-19?<\/h2>\n\n\n\n

OK, at this point, there must still be some skeptical readers out there. There\u2019s no way that surgical masks can capture particles that small! I saw a doctor on Quora say that \u201cmost masks\u201d can\u2019t capture particles the size of viruses and COVID-19.<\/p>\n\n\n

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\"It<\/figure><\/div>\n\n\n

But when we ignore our intuition and look at actual test data, reality is far more interesting. Test data shows surgical masks are surprisingly effective<\/a><\/span>, even for tiny particles<\/a><\/span>. For example, in one study, researchers tested particles down to .007 microns<\/a><\/span> (even smaller than viruses and COVID-19<\/a><\/span>) and found that a simple surgical mask blocked 80%.<\/p>\n\n\n

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\"surgical<\/figure><\/div>\n\n\n

Yet still, N95 and N99 masks outscore them<\/a><\/span>. For example, in that study, N95 masks captured 96% (see also 1<\/a><\/span>).<\/p>\n\n\n

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\"N95<\/figure><\/div>\n\n\n

So it\u2019s downright surprising that surgical masks are just as effective! Maybe virus particles are actually easy to capture because they fly on water droplets. Or maybe mask usage prevents people from touching their mouth and nose. For now, I can only speculate.<\/p>\n\n\n

Bottom Line<\/div>
Bottom Line: N95 Masks and Surgical Masks Are Equally Effective Against Viruses<\/div>
<\/span><\/p>\n

There\u2019s scientific evidence finding that (1) masks prevent flu infection and (2) surgical masks prevent infection of viruses like COVID-19, as well as more sophisticated N95 masks.<\/div>

Smart Air<\/div><\/div>\n\n\n\n

Breathe safe!<\/p>\n\n\n\n

P.S. Do we even know whether masks capture tiny virus particles? Aren\u2019t they too small for masks?<\/strong><\/p>\n\n\n\n

This is a solid intuition I\u2019ve seen several times, including here on Quora<\/a><\/span>, repeated by a doctor.<\/p>\n\n\n

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\"Can<\/figure><\/div>\n\n\n

The only problem it doesn\u2019t fit the data. I summarize that data here: Can wearing masks stop the spread of the coronavirus?<\/a><\/span><\/p>\n\n\n\n

<\/h2>\n\n\n\n

<\/p>","protected":false},"excerpt":{"rendered":"

Scientists have actually randomized people to wear N95 or regular surgical masks, then tracked how many people got infected with viruses similar to COVID-19 such as the flu. This data can tell us whether N95 or surgical masks are more effective at preventing infection of respiratory viruses including COVID-19. The … <\/p>\n

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