Health

Can my fan or air conditioner spread coronavirus? Your COVID-19 questions answered

Here are some of the answers to the questions on COVID-19 you asked us this week.

From fans to air conditioning, we answered your hot summer questions

Canada's public health agency said that air conditioning likely won't spread the SARS-CoV-2 virus, but you may want to be careful with fans. (Don Campbell/The Herald-Palladium/The Associated Press)

We're breaking down what you need to know about the pandemic. Send us your questions via email at COVID@cbc.ca and we'll answer as many as we can. We'll publish a selection of answers every weekday on our website, and we're also putting some of your questions to the experts on the air during The National and on CBC News Network. So far we've received more than 45,000 emails from all corners of the country.

Can the air blowing from air conditioning and fans spread the coronavirus?

We've received a lot of questions from readers like Amy C. concerned about the risks of catching the coronavirus from air conditioning and whether the units are safe to use during the pandemic.

First, it's important to understand that the virus that causes COVID-19 isn't airborne, according to the World Health Organization (WHO). The scientific consensus is the virus is primarily spread through droplets when an infected person coughs or sneezes. 

So could turning on the AC or a fan blow these droplets at you? 

In a statement, the Public Health Agency of Canada said there's "no evidence that the SARS-CoV-2 virus gets into and is dispersed by heating, ventilation and air conditioning systems."

The agency said that as a precaution, you should ensure "appropriate ventilation to reduce the risk of propelling droplets between spaces, especially from an infected person's space to that of others."

"The use of fans and single air conditioning units in an indoor space where the space is shared by multiple people could, potentially, facilitate the dispersion of infected droplets," it said.

That means that if someone who has the virus coughs or sneezes, and there's a fan in the room, the fan could potentially spread droplets further than they'd normally go. 

One preliminary, non-peer-reviewed study published on the Centers for Disease Control website suggests the source of a January outbreak of the novel coronavirus in Guangzhou, China, "was prompted by air-conditioned ventilation." 

The woman deemed to have been the source of the outbreak was seated in an air-conditioned restaurant with no windows and was more than a metre away from others who became infected and had no other source of exposure to the virus, the researchers found.

While transmission this way might be possible, air conditioning is not likely to be "the main mechanism of spread in most places," said Dr. Lisa Barrett, an infectious disease specialist at Dalhousie University.

William Bahnfleth, head of the COVID-19 task force formed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, said in the case of the restaurant, the absence of fresh air could have caused a "concentration of infectious material."

So while the research into the coronavirus and air conditioning and ventilation isn't conclusive, there are some things you can do to help ease your mind.

University of Toronto engineering professor Jeffrey Siegel recommends — depending on the space — increasing the amount of outside air, upgrading central air systems to remove particulates or adding portable filtration units in high-traffic areas. 

When it comes to fans, Quebec's public health body said pedestal fans should "not be used in the presence of an infected person unless this person is alone in an isolated room" that has a "consistent source of fresh air from the outside."  

As for whether the virus can spread through an HVAC unit, we answered that question here.

Can blow drying hair spread the virus?

Speaking of blowing air, readers like Rita M. are wondering if the hair dryer at the salon can spread COVID-19.

The experts we asked said it is a possibility, but there isn't any concrete data to back it up. 

Blow drying may spread droplet particles beyond "the two-metre radius that we normally talk about with breathing, coughing and sneezing," said Dr. Mark Downing, infectious disease physician at St. Joseph's Health Centre in Toronto. 

But "the risk is extremely low," said Dr. Zain Chagla, infectious disease physician at St. Joseph's Healthcare in Hamilton.

"If someone were to breathe, cough, or sneeze droplets while the hair dryer is running, it could technically push the droplet around," he said.

The risk of COVID-19 being spread by blow dryers at a salon is "extremely low," experts say — especially if the client and stylist are taking proper precautions. (Alexandre Lauzon/Radio-Canada)

"That being said, the dry air from the hair dryer as well as the heat will likely disrupt the virus within that droplet, making it less infectious."

The real risk in a salon doesn't come from blow dryers, our experts agreed, but from our close proximity to others and the potential contact with high-touch surfaces.

The Alberta government said blow drying is not recommended unless both the stylist and client wear masks. Our experts said that is something everyone should be doing anyway when physical distancing is a challenge. Both stylists and clients should be sure to wash their hands and avoid coming in if they're sick. 

Hair salons should also book appointments in advance to minimize walk-in traffic, maintain adequate spacing between customers — including in the waiting areas — and disinfect surfaces and equipment between each appointment.  

What about hand dryers in public washrooms?

Downing said there is some evidence that hand dryers can disperse "microorganisms that are on your hands into the environment around you." 

But there has been no documented transmission of COVID-19 infection from one person to another through hand dryers in public washrooms, he said.

It may be a good idea to skip the hand dryer if you can.

"It is really just not the cleanest way to dry your hands," Downing said. "Paper towels were the preferred option prior to COVID-19 and the same applies now."  

Saturday we answered questions about travel and hotels.

WATCH | We're also answering your questions every night on The National. Last night, we asked our medical specialists whether the pandemic will continue through the summer and whether recent protests could cause outbreaks.

An infectious disease specialist answers viewer questions about COVID-19, including whether the pandemic will continue through the summer and whether recent protests could cause outbreaks. 3:48

Keep your questions coming by emailing us at COVID@cbc.ca.

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