Most malls can't use HEPA filters, but there's an easier way to protect shoppers from COVID-19 particles

• New York Governor Andrew Cuomo seemed to suggest that malls use powerful high-efficiency particulate filters to fight the spread of COVID-19 in a June 29 briefing.
• Multiple news outlets reported that HEPA filters would be a "mandatory" requirement for indoor malls looking to reopen.
• HEPA filters are capable of capturing the COVID-19 virus, but are likely incompatible with most malls' heating, ventilation, and air conditioning systems.
• A subsequent statement from the governor clarified that "air conditioning filters with a Minimum Efficiency Reporting Value (MERV) rating capable of filtering COVID-19 particles or similar air exchange measures will be mandatory for large mall reopenings."

On Monday, New York Governor Andrew Cuomo suggested indoor malls should adopt a powerful class of air filters to protect shoppers from COVID-19.

Speaking about the state's coronavirus-related agenda on June 29, Cuomo brought up high-efficiency particulate — or HEPA — filters during his discussion of boosting air filtration capabilities malls. But installing HEPA filters may be technically untenable for most shopping centers, according to air filtration experts.

"There are HEPA filters that can filter out 0.01, so any malls that will open in New York — large malls — we will make it mandatory that they have air filtration systems that can filter out the COVID virus," he said.

While shoppers have been welcomed back into most retailers throughout New York state, stores at indoor malls have remained an exception. According to the Democrat & Chronicle, "only stores with exterior entrances" at indoor malls have been allowed to open their doors.

"We're currently talking to mall operators​ and as we've done with every step of our phased approach, we will issue guidance for the reopening of these facilities," Jason Conwall, a spokesperson for the governor, told Business Insider in a statement. "Further details will be included in the forthcoming guidance."​

And Cuomo's discussion about air filtration comes at a time that HEPA filtration is being touted as a potential safety measure against COVID-19. With a history dating back to the Manhattan Project, HEPA filters are defined as a "type of pleated mechanical air filter" by the United States Environmental Protection Agency. The New York Times reported that HEPA filtration is proven to "efficiently capture particles the size of (and far smaller than) the virus that causes COVID-19." COVID-19 virus particles are 0.125 microns, while HEPA filters pick up particles sized 0.01 microns and above.

But it's not as simple as slapping a HEPA filter on a mall's extant air filtration system. In fact, even attempting that could backfire in a big way, potentially leading to the extensive damage of a mall's heating, ventilation, and air conditioning system.

Mark Davidson, manager of marketing and technical services at Camfil USA, spoke to Business Insider about HEPA filters. The Camfil Group is an air filtration company based in Stockholm. Davidson said that adding a HEPA filter to an HVAC system is "the equivalent of driving an Indianapolis 500 car on the freeway to work."

"It's a great thing to have and it's got a lot of value, but it needs all of the surrounding environment to go with it," Davidson said.

Basically, HEPA filters provide such powerful filtration that they require specialized systems to operate properly, as well as strong enough fans order to ensure continued airflow through the filter.

"If you could find a way to stick a HEPA filter on your home's AC, the fan that's in your air conditioner isn't strong enough to suck air through those small openings," Davidson said. "So then you don't get enough air downstream and then you're starving for air. And if it's an air conditioning system and you did that, all of a sudden the room you're in is going to get hot because you're not getting enough air in there."

News outlets ran with the angle that Cuomo was mandating that malls install HEPA filters in order to reopen. But a statement put out later on June 29 clarified that the governor was announcing that "air conditioning filters with a Minimum Efficiency Reporting Value (MERV) rating capable of filtering COVID-19 particles or similar air exchange measures will be mandatory for large mall reopenings."

All filters can be graded with a minimum efficiency reporting value, or MERV, from 1 to 16. According to the EPA, MERVs "report a filter's ability to capture larger particles between 0.3 and 10 microns." More effective filters receive higher MERV ratings.

As a measure to mitigate the risks of the coronavirus, the American Society of Heating, Refrigeration and Air-Conditioning Engineers has recommended that, when possible, buildings opt for filtration systems of MERV 13 or higher or upgrade using portable HEPA filtration units.

Davidson said a filter rated a MERV 15 was powerful enough to target the respiratory droplets that serve as COVID-19 carrier particles. That kind of filter would not necessarily capture the COVID-19 virus itself, as it is too small. But it would effectively capture the larger respiratory particles carrying the virus According to the World Health Organization, the evidence indicates that COVID-19 is spread through droplet particles between 5 and 10 microns in diameter.

"That's much more likely to be usable in a lot of these systems that malls have in place," he said.