Hundreds of doctors, scientists call for action on COVID-19 aerosols

Hundreds of scientists, doctors, engineers and other experts are calling on Canada to take stronger action on limiting the airborne spread of COVID-19.

In a letter to premiers, public health officials, Chief Public Health Officer Dr. Theresa Tam and Health Minister Patty Hajdu, more than 500 signatories say while Canada recognizes the transmission of COVID-19 by aerosols, this recognition hasn't led to sufficient change to our behaviours or understandings about indoor air risks.

Ottawa emergency room physician Dr. Sarah Addleman helped draft the letter and is one of dozens of medical doctors who signed it. She says the government's focus on risks posed by large droplets that tend to land on surfaces or the floor has come at the expense of talking about aerosols — the small particles that can linger in the air, especially inside, for a long period of time and can even build in concentration. 

"I think it's really important that we all have a clear understanding of the transmission routes of COVID because this really informs all of our public health guidelines," she told CBC's All in a Day on Monday.

The open letter urges Canada to update provincial guidelines, workplace regulations along with public communications to reflect the fact that COVID-19 spreads through the air, not just by contaminated surfaces and touching our faces.

"With winter upon us, our activities are moving indoors and it is therefore imperative that workplaces, public institutions and individuals understand the risk of aerosol transmission as well as the actions that can be taken to combat it," the letter states.

Signatories call on the government to implement "control strategies" like improving ventilation in places like schools and long-term care homes, ensuring that all health-care workers have access to N95 masks or other fitted masks and developing clear ventilation guidelines for riskier businesses where masks are not always worn, like restaurants, bars and gyms.

"We know that many workplaces, buildings and residences in our communities have substandard ventilation," the letter reads.

Canada falling behind, signatories say

Addleman helped organize to bring HEPA air filters into classrooms in Ottawa's French public school board. She began pushing for the filters last year after seeing little in the way of a ventilation plan at her children's school.

"Other than keeping the windows open there wasn't a lot about ventilation and I wasn't sure how keeping the windows open all winter in Ottawa was really going to work," she said.

"At this point, we should be doing everything we can to increase the safety of our indoor spaces."

The letter follows an earlier call in November asking Ontario to take further steps to control airborne spread of COVID-19. CBC reached out to the province of Ontario for reaction to Monday's letter but has yet to hear back.

On its website the Public Health Agency of Canada advises hosts of gatherings, in areas where people are allowed to gather, to keep windows open and keep noise levels low to limit shouting. The agency also advises Canadians to avoid the three c's: closed spaces with poor ventilation, crowded places with many people and close faces, such as close-up conversations.

Monday's letter points out other countries like Germany have already invested millions into improving ventilation inside public buildings by upgrading air conditioning systems as well as providing air filters to schools. The doctors and scientists call on Canada to join other countries and be a leader in addressing problematic indoor air.

"Investing in ventilation, indoor air quality and appropriate personal protective equipment now will save lives and prevent economic hardship in the future," the letter reads.