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.

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?

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.

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.”

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.

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.

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.

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

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.

Britain, notably, seems to have figured this out. Officials have been more aggressive about restricting indoor behavior — and aren’t trying to get people to wear masks outdoors.

Despite the outdoor masklessness, Covid deaths are down 99+%. https://www.nytimes.com/2021/05/11/briefing/outdoor-covid-transmission-cdc-number.html?referringSource=articleShare