Increasingly, officials managing the reopening of local economies are focusing on the role of indoor air filtration to slow the spread of the virus that causes Covid-19. Governor Cuomo’s recent directive to businesses in New York State draws from guidance previously issued by the Centers for Disease Control and Prevention (CDC), the American Institute of Architects (AIA), and the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE). However, these recommendations are creating some real challenges in practical application for businesses not only in New York, but around the country, as they look to safely reopen and remain open without incident.
“The guidance from Governor Cuomo and the experts on indoor air quality essentially directs building owners to utilize the existing air handling system to catch and trap lingering viral matter so that customers, employees and other building occupants can have confidence that the air around them is safe,” explains Christopher Fox, president of R.P. Fedder Industrial, an air filtration company based in Rochester, NY.
Much of the virus matter exhaled by an infected person is on particles that will fall to the ground within a radius of six feet. Outdoors, the rest disperses quickly with air currents. Indoors, however, virus matter that doesn’t fall to the ground could linger in the air as an aerosol or attach to dust particles, which then get recirculated throughout the space. That means occupants spending extended time within an indoor space can be at risk even with social distancing and/or long after an infected person has left the premises. For this reason, much of the focus of indoor air quality has fallen on capturing (or “filtering”) the particles that contain the virus.
Not all filters capture particles equally; the filter’s efficiency is critical in determining its ability to capture the size of particles that contain viruses. (“Efficiency” refers to how much particulate of various sizes is captured by the filters.) ASHRAE has set a filter rating scale – referred to as MERV ratings—where a higher MERV number equates to a greater percentage of ever smaller particles captured by the filter. To remove virus matter from the air, an air handling system pulls air from the room, moves the air through a high MERV filter, and puts the filtered air back in the room. The air circulates through the system typically two to four times an hour, or once every 15-30 minutes.
While it may seem, then, that a building manager just needs to put in a higher MERV filter, it is not that simple. One challenge is that the MERV rating of a filter may deteriorate with time, sometimes in a matter of just weeks. “Many filters weren’t designed with life-saving functionality in mind, so declining MERV ratings didn’t matter. Now it matters because that filter is supposed to be capturing Covid-19 infected particulate,” says Fox. All filters sold in the United States must be tested per ASHRAE standards, and that test includes evaluating performance over the life of the filter. Fox recommends building managers look at a filter’s MERV-A rating, which more accurately represents the filter’s true efficiency in real-life applications.
Another challenge for building managers is that higher MERV filters reduce air flow, resulting in the air handling system working harder to pull the air through, which means more energy consumed. Fox points out, “Our energy consumption models, which we have validated in real-life environments, show that building owners can expect to see their electric bills increase $30 to $50 per filter per year, and more if they don’t change them frequently. Given the number of filters in a typical commercial building, that easily means thousands if not tens of thousands of dollars per year.”
There are ways to design a filter that will meet the higher-MERV rating and keep the energy bill down. While that increases the initial cost of the filter, it is more economical in the long run. “Most people would spend $5-$10 more on filters to save the $30 to $50 in energy if they were given that option, but in many businesses, the person buying the filters is not the person paying the energy bill, so that connection of cause and effect is never made,” adds Fox.
Lastly, there are situations where common sense suggests changing the air every 15 to 30 minutes just isn’t frequent enough given the use of space. For example, the air in a hospital operating room changes over and gets filtered every five to six minutes through High-Efficiency Particulate Air (HEPA) filters.
There are spaces within buildings that owners and managers might want to consider having an extra layer of protection to better protect their customers, employees, and themselves. Examples include spaces where:
- Many different people congregate or pass through for an extended period of time, such as lobbies, conference rooms, dining areas, and other common areas.
- People expel more air from deeper in their lungs, such as from cheering or singing or heavy exertion.
- Occupants need protections, such as in long term care facilities or critical service facilities
In these situations, in-room, portable, HEPA air purifiers can filter and clean the air more rapidly and independently of the air handling system. Many come with UV-C lighting internal to the purifier, which sterilizes any microbials that manage to get through the filters.
“Since April, we’ve provided more than 100 portable air purifiers with UV-C to our local hospitals and long-term care facilities. They work great, are simple to use, and give the room occupants an added sense of safety,” notes Fox.
Demand for air purifiers, especially those with UV-C, has now outstripped supply, and Fox warns the situation will only get worse. “The backlog for these devices is now six weeks, and growing longer,” he adds. “Inquires are coming in from schools, offices, restaurants, salons, dental and medical practices, most any place where people remain in a single place for an extended time.”
Fox expects that, even where not required, supplemental room air purifiers with UV-C will become the norm in many consumer businesses and offices. “People will take comfort in knowing that the air around them is safe, having been recently cleaned and sterilized,” he says. “They don’t want to have to be concerned with who might have been through the space previously or worry that someone on the other side of the office or restaurant or whatever might be contagious.”
R.P. Fedder designs and manufactures custom filters for thousands of engineered products used in industrial and medical applications. The company also warehouses and distributes a wide range of standardized air filters, liquid filters and commercial filtration equipment. More information about R.P. Fedder is available on the company’s website: http://www.rpfedder.com/.