COVID-19: RETURN-TO-OCCUPANCY (RTO) INDOOR AIR QUALITY CONCERNS
Indoor air quality (IAQ) concerns revolving around COVID-19 have been heightened with a report out of China which may have identified a link between HVAC systems and the spread of coronavirus. That study appears to be refuted, however by a more thorough analysis of the original study.
Unfortunately, there are not many laboratory studies on the impact of HVAC systems and spread of the virus because the government has not permitted outside testing of the virus.
Therefore, companies and organizations are making estimates with what they know from other viruses.
So, of course, the answer is, “maybe.”
What should I do?
Quality indoor air has been shown to improve productivity and reduce employee absenteeism. Therefore, regardless of COVID-19, it would be prudent to improve the air quality in your facility.
First, ensure that your systems have been properly serviced for the type of equipment you have. Though this seems obvious, HVAC systems are notoriously given short shrift when it comes to proactive maintenance.
I already do that.
Next, look at increasing natural ventilation. This can be a combination of opening windows, increasing mechanical ventilation rates, and enabling economizers more often.
Periodic flushing can be considered for the two hours prior to occupancy and the two hours after occupancy.
What about filters?
Better filtration can involve upgrading filters to a higher MERV rating. You cannot just install a higher MERV filter and walk away. An analysis needs to be made of the system to see if the increased pressure drop will have a negative impact. Impacts may include more frequent need to replace filters, leakage around the filter, and diminished amount of air supplied into the environment.
There has been much talk about UV-C lights within duct systems as a means to deactivate the virus. The details of the system are very important (e.g., design of fixtures, lamp type, lamp placement, airflow amount and mixing, etc.).
Moving forward on any of these measures will increase operating expenses. Increasing ventilation will result in more continuous running of air conditioning systems during the cooling season and thus higher electricity usage. It may also reduce motor life.
Employee productivity may be negatively impacted as a result in increased humidity. Not to mention mold development if humidity levels are allowed to rise beyond 60% RH.
Additional investment in upgraded filters and installation of UV-C lights will be additional expenses, as will maintaining the UV-C systems.
Because of the inability for commercial testing of the virus, all recommendations are based on best guesses for the immediacy of minimizing exposure. They have not been assessed for efficacy or for cost effectiveness. These are essentially emergency measures that are thought to best facilitate return-to-occupancy.