Extreme Temperature Diary- Friday July 3rd, 2020/ Main Topic: Can Air Conditioning Spread COVID-19?

Friday July 3rd… Dear Diary. The main purpose of this ongoing blog will be to track United States extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: Can Air Conditioning Spread COVID-19?

Dear Diary. First, as promised yesterday that I would start doing for the remainder of this summer, here is our daily assessment for any heat waves across the United States with a ranking of 1-5. Good news. Although seasonably hot for the Fourth of July weekend, we don’t have a heat wave, although small areas of heat advisories are in effect around Minneapolis and the Arklatex area:

Speaking of heat, more of us will be trying to stay comfortable this July using indoor air conditioning. But in these days of the COVID-19 pandemic is this healthy? Researchers are trying to find out whether or not COVID-19 can survive long in AC filtration or can be circulated in the air blown by such systems. Here is more from NBC:


Full coverage of the coronavirus outbreak


Does air conditioning spread the coronavirus?

June 26, 2020, 1:31 AM PDT By Akshay Syal

COVID-19 cases are spiking across Southern and Western states just as rising summer temperatures are drawing people indoors to seek relief in the air conditioning. But can air conditioning facilitate the spread of the coronavirus?

The question comes as states are allowing indoor businesses to reopen, as well as allow increasingly large gatherings of people.

Full coverage of the coronavirus outbreak

“There’s some reports that malls, bars, certain social clubs with air conditioning, that air conditioning may not be cleansing the air of the virus, just recirculating the air with the virus,” New York Gov. Andrew Cuomo said in a briefing Wednesday. “We’re studying that, and as soon as we get some more information, we’ll make an informed decision.”

New York, New Jersey, Connecticut governors announce quarantine for some out-of-state visitors

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But experts say there’s little evidence to link air conditioning to the spread of the coronavirus. Rather, the risk more likely comes from the amount of time spent indoors in close proximity to others.

“The opening up of facilities from my point of view, and I think this is shared by colleagues, that doesn’t depend on the air conditioning, it’s the gathering of the people for long periods of time,” said Dr. William Schaffner, a professor of preventive medicine and infectious diseases at the Vanderbilt University Medical Center.

“You can think of laboratory experiments and theoretical possibilities of how air conditioning might spread this virus, but so far, there really isn’t any noteworthy evidence that this is happening,” he said.

study published in April raised concerns that air conditioning could spread the coronavirus. The research, published in the Centers for Disease Control and Prevention’s Emerging Infectious Diseases journal, detailed an instance in which 10 restaurantgoers in China were sickened after eating at neighboring tables. The authors concluded that the virus was spread by the air conditioning system blowing tiny virus-laden droplets through the air.

Schaffner said this study may be an interesting outlier, but noted that there have been no further stories like this documented with the millions of infections worldwide.

Dr. Amesh Adalja, an infectious disease physician and a senior scholar at the Johns Hopkins Center for Health Security, agreed.

“I haven’t seen any strong evidence that we’re seeing that this is transmitted in an airborne manner,” he said. “This is primarily spreading from droplets that go from one person directly to another person.”



Is the coronavirus airborne? Here’s what we know.

While it’s theoretically possible that air conditioning can facilitate the spread of the virus, a lot of factors would have to align for that to happen, such as the timing of a cough or a gush of air at the right moment, Joseph Fair, a virologist and a NBC News contributor, said.

Spread through air conditioning isn’t a major factor in transmission, as the numbers don’t reflect that, he said.


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“If you think about how many Americans use AC, it’s 9 out of 10 of us, so we’d have a lot more [cases] than what we have right now,” Fair said.

With proper ventilation, coronavirus transmission shouldn’t be an issue, said Bill Bahnfleth, a professor of architectural engineering at the Penn State Institutes of Energy and the Environment. In the instance where the virus may have spread in a restaurant, the ventilation didn’t meet the standards used in the U.S., he said.

Download the NBC News app for full coverage of the coronavirus outbreak

“If you had ventilation at what I would consider a normal or appropriate level, the concentration may have never been high enough for any of those people to receive an infectious dose over the hour and a half that they were the same place,” said Bahnfleth, who is also a member of the American Society of Heating, Refrigerating and Air-Conditioning Engineers.

According to a statement in April from that group, heating, ventilation and air conditioning can actually slow the spread of the virus.

“Ventilation and filtration provided by heating, ventilating, and air-conditioning systems can reduce the airborne concentration of SARS-CoV-2 and thus the risk of transmission through the air,” the statement said. “In general, disabling of heating, ventilating, and air-conditioning systems is not a recommended measure to reduce the transmission of the virus.”

CORRECTION (June 26, 2020, 9:12 a.m. ET): A previous version of this article misstated one aspect of New York’s phase four reopening. Gov. Andrew Cuomo is looking into whether to reopen malls and gyms, in part over concerns that air conditioning may spread the coronavirus, but no decision to keep them closed has been made yet.

Follow NBC HEALTH on Twitter & Facebook.


I hope this information helps. My meteorological tea leaves are telling me that after the 4th it will get very hot even by July standards across a good chunk of the country, so get that AC system tuned up, and for COVID-19, as clean as possible.

Here is more climate and weather news from Friday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

(If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton “The Climate Guy”

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