Sudbury mining ventilation specialist urges businesses to consider better air flow in addition to distancing

As store owners continue to open their doors, they're making sure to think about the health and safety of their customers and staff.

Of course physical distancing measures are still in place, and many communities, like Sudbury, have made face coverings a required accessory for indoor public spaces.

But a Sudbury physicist who develops ventilation systems for the mining industry, feels we need to take more than just physical distancing into consideration when we're indoors.

Daniel Cluff is the CEO of CanMIND Associates, which develops ventilation systems for the mining industry. He even worked on the first clean room underground for the Sudbury Neutrino Observatory (SNOlab).

Clufffeels that physical distancing is important with COVID-19 to ensure droplets or large particles of the virus, from an infected person, fall to the floor instead of passing on to someone else.

He admits he's not a medical expert but he's been following much of the researchon ventilation systems connected to COVID-19.

He thinks it's possible that smaller particles could continue to linger, suspended in the air, long after the large particles have fallen.

"Eventually they might even hit the roof, depending on if there's a little bit of turbulence. As time goes by these [small particles] will build up."

In order to clear these built-up particles from the air within indoor public spaces, Cluff says proper ventilation is essential.

But he says there is a danger if the air flow speeds up or blows too quickly.

"The more the air is moving the more the larger particles can get entrained in the air, then it has the reverse effect. It's actually more dangerous because now you've got all the big particles flying around. They could splash you in the face, get in your eye."

He suggests a fine balance of air changing, called laminar flow.

Time, ventilation risk factors

Paul Bozek is a professor in the Occupational and Environmental Health Division with the Dalla Lana School of Public Health at the University of Toronto. He teaches about ventilation to students pursuing a career in public health.

He says the risk is low of contracting the virus through small particles in the air. But it's not impossible.

If air flow is closed off in a space, then anyone spending a long time in that space could be affected.

"It's not just distance when you're talking about living or working or shopping indoors. Time and ventilation canaffect your risk of being infected," Bozek said.

"For a well ventilated space where you're keeping your physical distance and you're minimizing your time, it's not a risk." He adds the same goes for just momentarily passing through a poorly ventilated space.

Research from recent cases

Bozek cites one instance where individuals contracted COVID-19 at a restaurant in Guangzhou, China.

A cluster of COVID-19 developed after several groups of patrons had been eating at tables which were far enough apart for physical distancing. It was the air conditioning unit that turned out to be the culprit.

To improve ventilation, Bozek suggests letting some outdoor air in to help dilute any indoor air that could have lingering particles of COVID-19.

Public Health guidelines

Bozek says he's rather disappointed with what the provincial government has offered up for ventilation directives on its website for businesses that are looking to reopen. It simply says to "Open doors and windows to let in more fresh air."

In an email to CBC News, Public Health Ontario (PHO) offered general advice on ventilation in indoor and general public settings, such as increasing outdoor air ventilation, maintaining air handling systems and possibly running them longer, and increasing air flows with portable fans and air conditioning.

PHO also added that reducing the risk of infection also means following current public health guidance, like physical distancing, and using a non-medical face mask while in indoor public spaces.