Scientists urge provinces to take action to curb aerosol spread of COVID-19

Doctors, engineers and microbiologists are recommending that provincial governments tighten public health guidelines, given COVID-19’s ability to spread through the air.

Recommendations include wearing a mask, even when distanced from others

Specialists say provinces should improve measures to protect health-care workers since the Public Health Agency of Canada identified the risk of COVID-19 transmission through aerosols. (Graham Hughes/The Canadian Press)

A group of health experts is calling on provincial health ministers to update guidelines to reflect the fact that COVID-19 is transmitted through the air. 

In an open letter sent Monday, more than 300 medical and scientific experts say provinces aren't educating the public enough about the risks of COVID-19 airborne transmissions in closed spaces. 

It comes as cases in Canada have steadily increased in recent weeks, with more than 600,000  COVID-19 cases and more than 15,000 deaths as of Jan. 4.

Among the various recommendations is promoting strategies such as wearing a mask — even when far from others — and avoiding closed or crowded spaces.

Specialists who signed the letter include doctors Amir Khadir and Alain Vadeboncœur, former Quebec health minister and doctor Gaétan Barrette and epidemiologist Nimâ Machouf.

"The message is completely unclear," said Dr. Marie-Michelle Bellon, an internal medicine specialist at Notre-Dame Hospital who also signed the letter. 

"It's rare that COVID-19 spreads through [contact with] objects, but people are always being told to wash their hands and disinfect door knobs. Disinfecting door knobs is great, but maybe we're devoting energy to something that would be better spent elsewhere."

Last July, 239 scientists from 32 countries called global health authorities' attention to the potential for the virus to spread by air. The Public Health Agency of Canada has since updated its guidelines and identified the risk of COVID-19 transmission through aerosols or respiratory droplets.

But signatories say the acknowledgement hasn't led to a noticeable improvement in measures to protect health-care workers and other workers in essential services. 

The experts are also asking provincial governments to: 

  • Inspect ventilation systems of public institutions, including schools and long-term care centres and fund their replacements. 

  • Hire engineers and other ventilation specialists to develop clear ventilation standards and incorporate those standards into guidelines for reopening businesses at higher risk of aerosol transmission, such as restaurants, bars, washrooms and sports.

  • Recommend and distribute carbon dioxide (CO2) monitors when ventilation is inadequate, to reduce the risk of distant airborne transmission.

  • Ensure that no high-risk health-care worker is denied access to a respirator (N95 or equivalent) whose fit hasn't been approved.

In an email, a spokesperson for the Quebec's Health Ministry said Monday the ministry is "interested in aerosol transmission" and waiting for Quebec's public health research institute, the INSPQ, and a group of experts to release reports on ventilation and COVID-19.

The report is expected in the coming days.

Ontario's Health Ministry, meanwhile, said Tuesday it recognizes evidence that COVID-19 can spread through aerosols and will "take appropriate action should the need arise."

"The vast majority of transmission of COVID-19 is by droplet spread between person-to-person," a ministry spokesperson said in an email.

with files from Radio-Canada’s Thomas Gerbet and Tout un matin


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