The pandemic that began a year ago has changed everything. From closed businesses and lost jobs to our hyper-awareness of the people who wander into our socially distanced space and undeniable fear of anyone who dares to cough in public.

We now know that the coronavirus that causes COVID-19 is not only on surfaces, but it lurks in the air as well. An infected person expels virus when they cough, speak or breathe. Larger respiratory droplets are heavy enough to fall to the ground within a few feet, but the tiniest particles are too light to fall, and can linger in the air for hours, traveling great distances from the source.

Clean air has always been an issue, but now we are fighting viruses at the micron level. To a large extent, the viability of businesses such as retailers, shopping centers, hotels, airlines, and commercial real estate are dependent upon the customer’s comfort level and their willingness to return.

Today’s technology offers four effective measures to clean and sanitize the air. All four have pros and cons, but can be used together to remove the vast number of particulates and pathogens in the air, no matter how small.

Red virus cell surrounded by positive and negative ions representing needlepoint bipolar ionization.

Bipolar Ionization

Also called Needlepoint Bipolar Ionization, it’s an air cleaning system that has been around for decades and is kind of having a moment. Bipolar refers to positive and negative ions. The system releases millions of them into the air stream. The ions cling to pathogens in the air, cluster around them, and disrupt the surface protein bond. Without it, the virus becomes inactive. Inactive viruses can’t make people sick. Laboratory studies by equipment manufacturers show up to a 99% reduction of airborne pathogens in minutes.(2) The ionization process does release ozone, though it’s a fraction of the amount released by ionization systems of the past. The amount released is minimal and would be negligible ten feet down the air duct.

Ultraviolet Germicidal Irradiation

UVGI has also been around for decades and is used to eliminate pathogens using UV light emitting radiation at a narrow bandwidth. UV-generated radiation kills pathogens by disrupting their DNA or RNA. It has a proven track record in hospital settings. The downside to UV is that the bulbs need to be replaced on a regular maintenance cycle. The pathogen also needs to be exposed to the UV for 10 to 15 minutes to kill it.

Outside Air Exchanges

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) provides standards for outside air exchanges in in different types of buildings. The minimum air exchange rate to dilute the air and reduce the risk of virus transmission is a six, which means the air in a building is replaced with outside air six times an hour. Most office buildings are only exchanging air at a rate of three or four times per hour. One way to increase the air exchange rate in a building is to open the economizer/air dampers on the HVAC system to bring in the maximum amount of outside air the system will allow. The problem is that HVAC systems have parameters, and by bringing in very hot or cold outside air and humidity the building may be uncomfortable, especially in extreme weather. This also means that energy costs may be increased.

Portable Air Purifiers

Portable air purifiers use both UV and bipolar ionization to render viruses harmless and exchange tainted air with clean air. There is a formula for figuring out how large of a machine is needed for a certain sized space, in order to bring that space to the equivalent of six air exchanges per hour. The formula incorporates the area of a room, the height of the ceiling and the number of individuals occupying the space. However, portable units may only have limited uses in multi-tenant and multi-story office buildings.

Filtration

Filtration alone is not enough to protect people from COVID-19. But it works well in conjunction with other methods such as bipolar ionization or UVGI. Typically, buildings will use a filter with a MERV-8. The coronavirus that causes COVID-19 can be as small as 0.1um, and a filter with a MERV-13 is required to trap particles this small. The problem with using high MERV filters is that it can result in a pressure drop in the HVAC system, as the fans work overtime to push the air through the system. This restriction of airflow can severely tax your HVAC equipment.

And finally, it is critical that your customers understand what you are doing, and that the air and surfaces in your building are clean. This requires a strong marketing campaign to convey this information. In our opinion, the airlines have done a great job by continuously reminding their customers about their clean air exchanges and cleaning procedures. It’s almost to the point where you feel safer on a plane than in a grocery store.

(1) Centers for Disease Control and Prevention. SARS-CoV-2 and Potential Airborne Transmission. (October 5, 2020) https://www.cdc.gov/coronavirus/2019-ncov/more/scientific-brief-sars-cov-2.html

(2) https://purifilabs.com/wp-content/uploads/2020/06/Surrogate-Aerosol-Test.pdf; https://globalplasmasolutions.com/independent-testing#field-testing