As Nell Thorn Restaurant & Pub in La Conner prepared to reopen for indoor dining late last spring, it wanted to go above and beyond in keeping customers and employees safe.

One step was to upgrade the restaurant’s HVAC system, said Albie Bjornberg, general manger and managing partner.

The upgrade included adding medical-grade MERV-13 filters that trap coronavirus particles, and increasing the amount of outdoor air that circulates into the space, he said.

“If I can take one extra step, or two or three extra steps, I’m going to do that,” Bjornberg said. “I want guests (and staff) to know that they are safe coming in.”

The business is also trying to keep windows and doors at least partially open through the winter to ventilate the space.

Though the restaurant is limited to takeout and outdoor seating until Jan. 4 due to COVID-19 restrictions, Bjornberg said he is “100%” sure it can provide a safe indoor dining experience when restrictions are lifted.

Other Skagit County businesses have also taken steps to make indoor air safer.

Increasing ventilation and air filtration indoors, when combined with mask-wearing and social distancing, can help reduce COVID-19 risk, the Centers for Disease Control and Prevention (CDC) states on its website.

The CDC’s recommendations include using portable high-efficiency particulate air (HEPA) filters, installing systems that disinfect the air with ultraviolet light, and keeping windows and doors open.

How air can transmit the virus

While the virus primarily spreads through close contact with an infected person, it can also spread through small droplets and particles that linger in the air for hours, in scenarios in which people are more than 6 feet apart or after an infected person has left the space, according to the CDC.

The CDC updated its website in October to acknowledge airborne transmission.

The Skagit Valley Chorale outbreak — in which a single infected person transmitted the virus to 52 others during a March choir practice and resulted in two deaths — is widely cited as evidence that the virus can spread through singing, breathing and talking, especially in poorly ventilated spaces.

In a video presentation posted to YouTube, Shelly Miller, a professor of mechanical engineering at the University of Colorado in Boulder, said ventilation and air cleaning can reduce “superspreading” events such as the Skagit Valley Chorale practice.

“We want to aggressively increase the ventilation rates, (and) do that by increasing outdoor air supply, opening windows and doors, and supplementing with additional air cleaning,” she said in the video.

Miller notes in her presentation that ventilation and air cleaning will not reduce spread of the virus between people in close contact (within 6 feet), which is why masks and social distancing are needed.

Investing in cleaner air

For Nell Thorn in La Conner, HVAC system upgrades, including regular maintenance, have cost more than $5,000, Bjornberg said.

Some businesses have taken it even further.

Anacortes dermatologist Andy Hines estimates he has spent between $15,000 and $20,000 this year on protocols to ventilate and clean the air in his building, which houses his business Anacortes Dermatology, a massage therapist and a naturopathic physician.

He added a medical-grade HEPA filter to his HVAC system to ensure that “even if someone outside your room had COVID, the air coming through the vent is purified,” he said.

The air inside patient rooms is further treated through standalone HEPA filters and ultraviolet light.

“The total air volume in our entire exam room is filtered approximately every 2.5 minutes,” Anacortes Dermatology states on its website. “This means during the average appointment, the air in our exam room will have been purified over 12 times.”

Hines said he was familiar with steps to reduce airborne transmission of viruses because of experience working in laboratories and in tuberculosis units in hospitals.

He said because patients may need to remove masks for certain procedures, he wanted to do everything he could to keep them safe.

“I didn’t really see another choice,” he said.

Hines has implemented another protocol to clean the air. He performs daily ozone-gas sanitation of exam rooms, which occurs at night when no one is in the building and the process is activated remotely, he said.

On Anacortes Dermatology’s website, results are posted from a test showing that ultraviolet light and ozone treatments killed 99.9% of respiratory bacteria on exam room surfaces.

“It sounds like really extreme, but in order for me to sleep at night and make sure my patients don’t get sick, I have to do that,” Hines said.

There are far simpler — and cheaper — steps to making indoor air safer.

In Mount Vernon, elSage Designs purchased two portable air purifiers with HEPA filters in November for about $600, said owner Phoebe Carpenter Eells.

She bought the purifiers to help make the space safer during winter, when the clothing/gift shop would be unable to keep its doors open for fresh air.

“We’re still strict about everyone wearing masks,” Carpenter Eells said. “It’s an added precaution.”

She said she also plans to use the purifiers during smoky wildfire seasons.

Miller, the University of Colorado professor, recommended in a blog post on her website that people do research before buying a portable air cleaner. She has produced a report, which is available online, that recommends brands and includes prices.

There is also a downloadable calculator, developed by the university and the Harvard T.H. Chan School of Public Health, to help people select the right portable air cleaner based on the size of a room and how much outdoor air ventilation they have.

A layered approach

In downtown Oak Harbor, third-generation commercial building owner Sarah Schacht has been thinking about making indoor spaces safer since the start of the pandemic.

Because of her background in public and environmental health, she watched closely as scientists demonstrated how COVID-19 could spread indoors through the air.

She purchased air purifiers for her tenants and installed transoms — small windows above doors — to improve ventilation.

Schacht said similar steps can make air safer inside homes. She said many last summer bought air purifiers with HEPA filters to protect against wildfire smoke particles, and they should turn them back on.

“Many of us unwittingly purchased one of the strongest protections we could possibly have,” she said.

She said there are also zero-cost steps, such as opening windows or turning on bathroom and kitchen exhaust fans, which suck indoor air out of a room.

Schacht recommends another tool — a carbon dioxide monitor. While it won’t measure the virus in the air, it can tell you if your space is stuffy and needs to be ventilated, she said.

She said the strongest protection is a “layered approach” that utilizes multiple strategies to create safer indoor environments. Public health agencies need to do more to educate businesses and individuals on how they can make indoor spaces safer, she said.

”It is not enough to just encourage mask use, distancing, and staying at home,” Schacht said. “We need more tools to reduce the risk.”

She said such an approach could help struggling small businesses reopen and operate safely.

— Reporter Jacqueline Allison:, 360-416-2145, Twitter: @Jacqueline_SVH

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