The SARS-COV-2 viral pandemic has changed most aspects of our work and home lives. Dentists are on the frontlines of possible exposure to the SARS-COV-2 virus that causes COVID-19 disease. Recent case studies have identified the likelihood that the virus is most commonly being transmitted via aerosols. Dentists have the highest risk of exposure to asymptomatic carriers of the virus due to working in the mouth. Not only that, common dental procedures produce aerosols suspended in the air that could contain the virus from asymptomatic carriers.
High cost advanced PPE (personal protective equipment) like n95 masks and face shields are used to protect the dental team. However, once aerosols are generated, they can circulate thru space and pose a risk to unprotected individuals. Containing and controlling aerosols is a major focus in dentistry. Many dentists are using enhancements to their HVAC (heating, ventilation, air conditioning) systems to help filter out potentially disease-causing aerosols. Stand-alone HEPA filtration units incorporating UV light disinfection (air purifiers) are the easiest way of improving air quality. Most of these units however do not have uniform regulatory certification of efficacy. They may have undergone consumer product testing, but none have certified the ability to fully capture and kill SARS-COV-2 virus.
One can assume that a HEPA filter would trap the most likely sized aerosol particle that could carry the SARS-COV-2 virus 99.9% of the time. Like n95 masks however, the HEPA filter does lose efficiency over time. The UV light will deactivate virus but this depends on the speed of airflow and how much UV contact time is necessary for kill. The analogy is driving your car thru the carwash at 30 miles an hour. How clean will it really get?
In addition to stand-alone air purifier units, there are other options that could be used to improve air quality. HVAC contractors can install powered HEPA filters to existing systems. These improvements can run from $3000-$8000 per unit. However, improving filtration can be as simple as changing to higher quality filters on the HVAC unit. The American Society of Heating and Air-Conditioning Engineers (ASHRAE) created Standard 52.2-2017 to describe Minimum Efficiency Reporting Value (MERV). It is possible to purchase MERV 12-16 filters that can be a significant improvement over most common furnace filters.
Added filtration will require more frequent filter changes and some filters (especially dirty filters) will reduce the efficiency of heating and cooling because of lowering airflow. A common problem with insufficient airflow is a frozen AC coil within the HVAC unit. This will cause lack of cooling and water pooling around the HVAC unit. An inconvenience, but easily remedied. More dangerous is low flow during the heating season which can cause a crack in the furnace leading to Carbon Monoxide poisoning.
Before doing any modifications, contact your local HVAC service provider. For more information on air quality, go to ASHRAE: https://www.ashrae.org/technical-resources/filtration-disinfection
The links below contain more technical information regarding advanced filtration: https://www.energyvanguard.com/blog/understanding-filter-ratings-merv-fpr-and-mpr
https://www.energyvanguard.com/blog/unintended-consequences-high-merv-filters Dr. Panek is a private practice Oral & Maxillofacial Surgeon practicing in Grand Rapids, MI.
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