The CDC says that “less than 10%” of Covid transmission occurs outdoors.
Which sounds like a lot of outdoors transmission. If anything close to 10% was correct, it would mean thousands of deaths were from outdoors transmission.
But the number doesn’t stand up to scrutiny. 
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If you read the academic research that the CDC has cited in defense of the 10% benchmark, you will notice something strange. A very large share of supposed cases of outdoor transmission have occurred in a single setting: construction sites in Singapore. How could that be?
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In one study, 95 of 10,926 worldwide instances of transmission are classified as outdoors; *all* 95 are from Singapore construction sites. In another study, four of 103 instances are classified as outdoors; again, all four are from Singapore construction sites.
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It turns out that academic researchers defined places that were a mix of indoors and outdoors as outdoors. One study defined all of these settings as outdoors: “workplace, health care, education, social events, travel, catering, leisure and shopping.”
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In the case of Singapore, some of the supposedly outdoor construction sites had many enclosed spaces. So there is a very good chance that many of these transmissions classified as outdoors were actually indoors.
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And yet even counting all the Singapore cases as outdoors still suggests only about 1% of transmission was outdoors. Other studies — from Ireland and China — put the share at 0.1% or less.
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Saying that less than 10 percent of Covid transmission occurs outdoors is akin to saying that sharks attack fewer than 20,000 swimmers a year. (The actual worldwide number is around 150.) It’s both true and deceiving.
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The CDC’s exaggeration of outdoor transmission isn’t just a gotcha math issue. It is an example of how the agency is struggling to communicate effectively, and leaving many people confused about what’s truly risky.https://www.nytimes.com/2021/05/11/briefing/outdoor-covid-transmission-cdc-number.html?referringSource=articleShare …
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The government list of recommendations is so long and complex that it’s useless to many people, as
@zeynep has noted. All the while, the scientific evidence points to a much simpler conclusion: Masks make a huge difference indoors and rarely matter outdoors.51 replies 114 retweets 873 likesShow this thread -
Replying to @DLeonhardt @zeynep
What about an outdoors Supreme Court nomination party?
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It was a multi-day event with a large indoor component.
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