Air purifiers have become a hot commodity during the coronavirus pandemic, with demand soaring especially during the winter months.
“The demand for air purification products, in general, has really skyrocketed under SARS-CoV-2,” said Dr. David Kirschman, founder and president of Aerobiotix, an American company that specializes in air disinfection technology.
A portable high-efficiency particulate air (HEPA) filter forces air through a fine mesh that traps air particles, removing viruses and germs from the atmosphere. But if not placed well, experts say it may not be effective and could end up increasing the risk of airborne virus transmission.
“Some air cleaners create a jet of air, particularly going downwards, and if that goes on a surface, it could resuspend or cause droplets to go back into the air,” said Jeffrey Siegel, a professor of civil and mineral engineering at the University of Toronto, in an interview with Global News.
But there is a simple solution, he said. Just elevate the device by putting it on a stool. Siegel also suggested moving the air purifier away from the wall and preferably towards the centre of the room to get the maximum benefit from it.
Last month, Quebec Public Health recommended against installing air purifiers in classrooms. The agency said the purifiers could have the adverse effect of spreading the virus.
During a Jan. 8 press conference, Dr. Richard Masse, the agency’s strategic medical advisor, laid out five reasons for the recommendation. He said there is not enough evidence that purifiers can limit transmission, they are not efficient over a large distance and if not placed well, this could cause droplets to suspend in the air. He also said they can be noisy and can create a false sense of security.
Siegel said he was “very surprised by those comments,” adding: “They’re not supported by evidence.”
While there is a technical possibility for air purifiers to spread droplets, Siegel said the known benefits outweigh the “tiny risk of harm.”
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Ohio-based Aerobiotix manufactures air decontamination systems that use ultraviolet (UV) light to clean the air. Their devices are currently being used in U.S. hospitals, nursing homes, schools and government buildings. A first shipment arrived in Canada last month.
Kirschman told Global News the units, based on clinical trials, have proven to be effective in killing SARS-CoV-2, which causes the COVID-19 disease. They were specifically designed to avoid horizontal airflows, he said.
“One of the risks of any kind of ventilation system is it can create too much airflow in a room and that can blow in from one area or one person onto another.”
With a variety of air cleaning products on the market, picking the right one is important.
Checking consumer reports can helpful, as well as the clean air delivery rate (CADR), which is a measure of its cleaning power.
“There are certainly types of air cleaners which people do not want to be buying,” Siegel said.
These include ionizers, bipolar ionizers, plasma air cleaners and photocatalytic oxidation purifiers, he said.
“There’s no direct independent evidence that they work at all and some of them can also emit byproducts that are harmful, ozone being the big one.”
Other ways of making indoor spaces safer include natural ventilation by opening a window or door and through efficient heating, ventilation and air conditioning (HVAC) systems.
Humidifiers, fans and UV light can also be helpful in improving indoor air quality.
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