HEPA Filters May Assist In The Fight Against COVID-19


Harvard environmental health researcher Joseph Gardner Allen was one of 239 scientists who wrote an open letter to the World Health Organization and other health agencies asking for a change in their guidance to the public on how coronavirus can spread.

Current guidance only focuses on "hand washing, maintaining social distancing, and droplet precautions," the letter said.

The health agencies are ignoring the tiny droplets of virus that sputter and spray from our mouths, become aerosolized and then float away into the air.

"They don't want to talk about airborne transmission because that is going to make people afraid," co-author Donald Milton, a professor of environmental health at the University of Maryland said. "The best vaccine against fear is knowledge and empowering people to take care of themselves. Why wearing a mask is important is because it blocks the aerosols at their source, when it is easy to block them."

A study found SARS-CoV-2 can survive in microscopic respiratory droplets which can remain airborne and viable for up to three hours or more.

Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, made a groundbreaking discovery that flu virus could float in the air in microscopic droplets for an hour or more. Top-rated N95 and surgical-grade masks will work against the droplets, and scientists are scrambling to study and tweak the effectiveness of homemade masks.

New York mall owners are talking about HEPA filters, which have the highest MERV (minimum efficiency reporting value) ratings, between 17 and 20. The MERV ratings go from one to 20: Filters with higher MERV ratings are more effective than filters with lower ratings.

HEPA filters are used by hospitals to create sterile rooms for surgeries and to control infectious diseases. Unfortunately, most businesses and home owners may find it difficult to retrofit their existing system. Doing so can actually impair the system's performance.

So, what should one do? Focus on following public health recommendations, wear masks, stay away from large crowds, wash your hands with soap frequently, and try to only go to outdoor locations with excellent air circulation and filtration.

There are also personal HEPA air purifiers on the market that can clean a standard room of a home. Some have built-in humidifiers that will measure the air and keep the room between 40% and 60% humidity, and others incorporate UV light technology that can kill airborne germs.

"Properly balanced UV light will inactivate viruses and bacteria in the air, which just adds an extra layer to the protection coming from the air purifier," Bromage said.

They can cost from a few hundred dollars to over a thousand dollars. No matter the price you're looking for a machine with a HEPA filter designed for the size of your room. If the machine that you purchase is too small for the room won't clean the air. Keep in mind that HEPA filters can be expensive!

Some say that the cost of filters and the expense of retrofitting buildings may not be worth the money. "That's not always the case", Allen said.

"It's a total misnomer that healthy building strategies and higher ventilation rates and filtration are expensive strategies," Allen said. "When people know and understand how it's transmitted, then they're empowered to make better decisions.

"And that includes right in your home: You'd have people over, open up those windows; you're in your car with somebody else, roll down the window, a few inches," Allen said.

"No one strategy alone is going to work. But if we layer enough of these on top of each other, we can significantly reduce risks."

Photos by Getty Images


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