According to the Centers for Disease Control (CDC), the SARS-CoV-2 virus, cause of COVID-19, is thought to be transmitted via person-to-person contact, contact with contaminated surfaces, and airborne droplets. In light of this conclusion, Americans are being urged to follow certain protocol and etiquette for general protection.

The greatest risk of transmission is present in interpersonal contact and aerosolized droplets from sneezes and coughs. Below are a few things that can be done in your facility to reduce the likelihood of virus surviving in the indoor air.

Indoor Air Quality

KERAMIDA recommends the management of indoor air quality (IAQ) parameters consistent with standards from the American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE). 

Relative Humidity (RH)

Viral inactivation occurs at a faster rate when RH is 50%.

• It is a convenient truth that the same RH parameters encouraged by ASHRAE for optimal comfort are in agreement with viral transmission studies performed by several credible entities over the years. In 2010 a study was published in the Journal of Applied and Environmental Microbiology which undertook the task of determining the effects of RH on coronavirus survival time on hard, non-porous surfaces. 

• The study concluded that at 68°F the survival time at 50% RH was approximately 72 hours, while the survival time at 20% RH was up to 28 days. The test was also performed at 80% RH, and the resulting survival time was approximately 14 days. Viral inactivation occurred at a faster rate when RH was 50% rather than at either 20% or 80%.

Temperature

Higher temperatures appear to reduce the survivability of the virus better than cooler temperatures do. 

• The same study mentioned above also addressed the temperature aspect of coronavirus survivability. Tests were performed at 39.2°F, 68°F, and 104°F. The resulting data indicated that at any RH level, survivability was lowest at the highest tested temperature. The ambient temperature of 68°F performed better at deactivating the virus than 39.2°F but neither performed as well as 104°F.

Filtration

HEPA filters are effective.

• Generally, the highest level filter readily accessible and used in HVAC configurations are those rated as High-Efficiency Particulate Air (HEPA) filters. HEPA is defined as a filter capable of removing 99.97% of particles 0.3µm in aerodynamic diameter, with efficiency increasing for particles that are both larger and smaller than 0.3µm.

• Coronavirus virion have a diameter of approximately 0.120µm. This means the HEPA filtration rating is appropriate for capture of the particles of concern. Though these virion are smaller than the pore size of a HEPA filter, the effects of Brownian Motion retain these particles when flow rates do not exceed recommendations of the filter manufacturer.

Maintaining these parameters does not ensure virion will not survive on surfaces as other factors exist; however, a reduction of survivability rates has been observed. The research mentioned above was performed on transmissible gastroenteritis virus (TGEV), a non-human coronavirus, as a surrogate. Another similar study was performed by the CDC on flu virus survivability in air with results showing approximately 55.5% reduction in survivability at RH >43% when compared with RH <23%.

KERAMIDA recommends adhering to all CDC public guidelines for sanitizing surfaces and avoiding transmission factors. 

KERAMIDA is prepared to assist with your Indoor Air Quality concerns as well as the development of plans for Coronavirus decontamination and inhibition of Coronavirus or other contaminants, biological or chemical. Contact us today or call (800) 508-8034.

Blog Author

Dan Engling, M.S., CIH
Director of Industrial Hygiene Services
KERAMIDA Inc.

Contact Dan at dengling@keramida.com.