Everyone Thinks Theyre Right About Masks – The Atlantic

Is it safe to go outside?

Even if coronavirus particles can move through the air, they would still diffuse over distance. People envision these clouds of viruses roaming through the streets coming after them, but the risk of [infection] is higher if youre closer to the source, says Linsey Marr, who studies airborne disease transmission at Virginia Tech. The outside is great as long as youre not in a crowded park.

In February, scientists in Wuhan, Chinawhere the coronavirus outbreak originatedsampled the air in various public areas, and showed that the virus was either undetectable or found in extremely low concentrations. The only exceptions were two crowded sites, one in front of a department store and another next to a hospital. Even then, each cubic meter of air contained fewer than a dozen virus particles. (No one knows the infectious dose of SARS-CoV-2that is, the number of particles needed to start an infectionbut for the original SARS virus of 2003, one study estimated somewhere between 43 and 280.)

These particles might not even have been infectious. I think well find that like many other viruses, [SARS-CoV-2] isnt especially stable under outdoor conditions like sunlight or warm temperatures, Santarpia said. Dont congregate in groups outside, but going for a walk, or sitting on your porch on a sunny day, are still great ideas.

Read: This is how we can beat the coronavirus

You could tie yourself in knots gaming out the various scenarios that might pose a risk outdoors, but Marr recommends a simple technique. When I go out now, I imagine that everyone is smoking, and I pick my path to get the least exposure to that smoke, she told me. If thats the case, I asked her, is it irrational to hold your breath when another person walks past you and you dont have enough space to move away? Its not irrational; I do that myself, she said. I dont know if it makes a difference, but in theory it could. Its like when you walk through a cigarette plume.

Indoors, experts opinions start to diverge. Consider, for example, the grocery storeone of the last vestiges of public life. There, Santarpia is far more concerned about touching shared surfaces than breathing shared air, and he makes sure to sanitize his hands before he leaves. Marr said that she tries to go when its less crowded, although thats obviously harder in a big city. Bourouibas best advice is to always keep as much distance from other people as possible, and she adds that the onus is on stores to improve their ventilation or limit the number of concurrent customers. Stores must also devise ways of protecting the people at greatest risk: the cashiers and the workers stocking shelves.

Then there are shared spaces like hallways, stairwells, and elevators in apartment buildings. Elevators pose the highest risk, Bourouiba told me, since theyre enclosed boxes with limited airflow. For stairwells and hallways, she advocated a commonsense approach: If you hear neighbors going out, and there are 10 people in the corridor right now, maybe wait and go later.

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Everyone Thinks Theyre Right About Masks - The Atlantic