What makes the COVID-19 corona virus so much more contagious and lethal is its ability to be spread by asymptomatic carriers. Asymptomatic hosts may appear healthy, pass temperature tests, and show no visible symptoms, while simultaneously transmitting the virus. When this fact is coupled with a room with inadequate or poor ventilation, it can lead to a “Super Spreader Event”, as was the case in the famous restaurant in Guangzhou China, the call center in South Korea, and many others. In fact, over 70% of all “Super Spreader Events” occurred in confined rooms with poor or inadequate ventilation.

There are three primary mechanisms that are believed to be vehicles for spreading COVID-19: surface contamination; an infected person sneezing or coughing on you; and airborne transmission of the virus as an aerosol. The first two of these we can personally control by washing our hands, wearing a mask, and practicing social distancing. But it is the third mechanism that requires the help of building owners and managers, and the responsibility for us to ask some questions to protect our health and safety.

A recent report from the National Academy of Science noted “speech droplets generated by asymptomatic carriers can emit thousands of oral fluid droplets per second. In a closed, stagnant air environment, they can be visible (using laser scattering techniques) for 8 -14 minutes. These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments.”

As we prepare to return to “life as normal” and consider re-entering our places of work/worship/play/education/dining, there are a few questions you should ask the people responsible for the air quality in these facilities:

• When was the last time (if ever) this building has been commissioned to ensure room(s) have the proper number of Air Changes per Hour (ACH)? There are standards for the number of ACH’s for the room type, dependent on occupancy and function. Commissioning ensures these standards are being met. Many buildings were never properly commissioned as it is often eliminated as a way to reduce initial building cost. Others have not been checked (recommissioned) in years. A recent study by Imperial College and Penn State at a high school in the US concluded that increasing the ACH to the standard set by ASHRAE was as effective as vaccinating 60% of the occupants (and it can be done now).

• When was the last time the filters in the heating/cooling system have been checked/changed? The current recommendation is to increase the MERV (Minimum Effective Rating Value) level by at least 1-2 levels, which provides improved air filtration for small airborne particles.

• Has the amount of outside air to the heating/cooling system been increased to improve air quality? ASHRAE is recommending all building managers increase the percentage of outside air to reduce the likelihood of pathogen entrainment.

• Is the air in this building being monitored for quality? Continuous air monitoring is important to help identify problems quickly. Good record keeping is necessary to establish patterns of acceptable air quality.

Most of us are not in the habit of considering the HVAC system in the rooms in which we spend a large portion of our time. The issue of poor or inadequate ventilation has historically been an issue of thermal discomfort (some occupants are too hot; some are too cold). However, with the high likelihood that the transmission of COVID-19 occurs through airborne transmission in confined spaces, it now becomes a much more important issue. I highly recommend you ask some of these keys questions before getting back to your place of work/play/worship/education/dining/entertainment so we know they are safe for us to return.