As Covid-19 continues to sweep across the United States and the world, many facilities have concerns with regard to the indoor air quality. Air filtration products are one component of a harm reduction or mitigation strategy to lower the probability of infection within a commercial facility. Please refer to the Center for Disease Control and the World Health Organization for guidance in terms of prevention from acquiring illness. Our focus as a company continues to be in providing the appropriate air filtration customized for each application.
How Does COVID-19 Spread?
COVID-19 is thought to spread mainly through close contact from person-to-person. Some people without symptoms may be able to spread the virus. We are still learning about how the virus spreads and the severity of illness it causes.
Person-to-person spread
The virus is thought to spread mainly from person-to-person.
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- Between people who are in close contact with one another (within about 6 feet).
- Through respiratory droplets produced when an infected person coughs, sneezes, or talks.
- These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs.
- COVID-19 may be spread by people who are not showing symptoms.
The virus may be spread in other ways
It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes. This is not thought to be the main way the virus spreads, but we are still learning more about how this virus spreads.
Source: CDC
Does COVID-19 Spread Through Airborne Droplet Nuclei?
There is mounting evidence that a secondary source of transmission may be through airborne droplet nuclei. Corona virus infects a host and exists within the moisture droplets that we expel into the environment through talking, singing, coughing, sneezing, etc.. The moisture droplets are called Droplet Nuclei. Those droplets that are larger in size (>40 microns) will fall to surfaces quickly within 6 feet of the source. Smaller droplet nuclei (Generally 1-5 Microns) have the potential to remain airborne for longer periods of time. In Healthcare and Commercial facilities, the HVAC system is designed to run and recirculate air within the space. These smaller particles could be picked up by the HVAC system and dispersed to adjacent areas within the facility. Currently there are non-peer reviewed research studies that support the possibility of airborne transmission.
Some of the strongest evidence that airborne transmission of the new coronavirus may be possible comes from a study published late last month in Nature. In it, researchers measured the virus’s genetic material, or RNA, in aerosols sampled in February and March at two hospitals in Wuhan, China—the city where the outbreak is widely believed to have begun. The researchers found very low levels of airborne viral RNA in the hospitals’ isolation wards and in ventilated patient rooms. But there were measurably higher levels in some of the patients’ toilet areas. They also found high levels of viral RNA in places where medical workers remove protective gear, as well as in two crowding-prone locations near the hospitals. “Our study and several other studies proved the existence of SARS-CoV-2 aerosols and implied that SARS-CoV-2 aerosol transmission might be a nonnegligible route from infected carriers to someone nearby,”
Source: Scientific American: How Coronavirus Spreads through the Air: What We Know So Far
What Level of Filtration Should I Use For COVID-19
In all filtration applications a facility must identify the target size range for the contaminant that we would like to capture. In this case, COVID-19 is thought to have a size range of 0.12 microns. This would mean that only HEPA filtration (Minimum 99.97% on 0.3 microns, >99.99% on smaller and larger particles) would be effective. That is a not true though, since the virus does not exist outside of host in its natural state and size range. The COVID-19 virus must be carried into the environment within a droplet nuclei moisture particle. As stated above, larger droplets are deposited on surfaces within a 6 foot range. Smaller droplet nuclei have an general size range of 1.0 – 5.0 microns in size. So our target particle of concern is airborne particles in the 1.0 – 5.0 micron size range. Increasingly higher levels of filtration product efficiency lowers concentration levels within the airstream. This leads to reducing the probability of infection. Various organizations have now published guidance on what efficiency of air filtration product is effective on reducing COVID-19 particles. ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), is now recommending:
- MERV ranges from 1 to 16; higher MERV = higher efficiency
- MERV ≥13 (or ISO equivalent) are efficient at capturing airborne viruses
- MERV 14 (or ISO equivalent) filters are preferred
- High efficiency particulate air (HEPA) filters are more efficient than MERV 16 filters.
Source: ASHRAE: COVID-19 Technical Resources
The reason for this recommendation is that MERV 13 – 16 filtration products have the following collection efficiencies of airborne particulate in the 1.0 – 3.0 micron size range, when tested for the ASHRAE 52.2 standard:
- MERV 13: > 85%
- MERV 14: > 90%
- MERV 15: > 90%
- MERV 16: > 95%
Following this logic, these levels of filtration offer the opportunity to reduce the airborne concentration level of particles in our contaminant size range of concern.
Filter Technology Company agrees with this assessment and as a filtration product distributor, we have numerous solutions for this application that will install directly into existing air handler filter housings with no need for modification.
Contact us at 1-800-874-1045 or sales@filtertexas.com to schedule a meeting with a Certified Air Filtration Specialist.