Masks for Coronavirus May Be Lowering Blood Pressure for Millions

The coronavirus has made millions around the world regularly wear masks to reduce the spread of the virus. It is clear, masks help mitigate virus spread. But widespread mask wearing may be having another unintended benefit: lowering blood pressure for millions.

With mask wearing to prevent coronavirus spread, people are accidentally protecting themselves from air pollution. Whoops!

Let’s take these subway riders I saw in Beijing in January. Everyone’s masked up.

Mask Wearing on Beijing Subway (masks lowering blood pressure)

Well, except this guy, who seems to be floating blissfully in his own world.

Mask Wearing on Beijing Subway (masks lowering blood pressure)

 

What are the Health Effects of Wearing a Mask?

Are all those masks doing anything? We can get a rough estimate of the effect size from this study.

Mark Cardiovascular Heart Benefits (masks lowering blood pressure)

In this study, researchers randomly assigned people to wear N95 masks or no mask.

N95 Mask Helps Lower Blood Pressure

Then they walked around central Beijing, near the Forbidden City (that rectangle on the right).

masks lower blood pressure test

While they walked, devices were tracking their blood pressure, heart rate, and other metrics. The masks lowered people’s blood pressure and improved their heart rate variability.

masks lower blood pressure

Thus, we could infer that all this mask wearing is lowering people’s blood pressure.

But That’s Just One Study 

That’s only one study, and there aren’t many studies like this. However, another study replicated the results. It’s also consistent with studies that have randomly assigned people to use their air purifiers at home and found that it lowered their blood pressure.

Masks Lower Blood Pressure

But Those Are N95s…

OK, OK, but those are N95 masks. For the coronavirus, lots of people are wearing weaker surgical masks or even cloth masks. Those things can’t capture tiny pollution particles, right?

Cloth Masks Lower Blood Pressure

The data is surprising. Let’s take an extreme example. Researchers tested a cheap surgical mask they bought off the streets of Kathmandu.

Street Masks Lower Blood Pressure

Let’s look at 1-micron particles. Those are about 1/60th the width of a human hair.

Air Pollution Raises Blood Pressure

For those particles, the surgical mask captured as much as the N95 mask—over 90%.

Masks Lower Blood Pressure

For the smallest 0.03-micron particles (30nm), the N95 did better. But the cheap surgical mask still captured over 60%. Surprising, no? But this is just one of several studies that have found that surgical masks are surprisingly effective against pollution, even after taking into account how tightly they fit.

Bottom line: Masks may be lowering blood pressure for millions

Based on the data, we could estimate that cotton and surgical masks could improve people’s blood pressure and heart rates. Those effects might be approximately 30–50% of the effect of N95 masks.

Masks Lower Blood Pressure

P.S. Caveat
This data doesn’t address gas pollutants like NO2 and O3. Masks like N95s capture particles, not gases. Thus, they’re good, but not 100% protection. But they’re good enough for me to bike through Delhi traffic.

Masks Lower Blood Pressure


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