Traci Hanegan, is a mechanical engineering principal with Coffman Engineers. She is an American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) fellow and a frequent lecturer about the impact of indoor air hydration on occupant health and the spread of infectious diseases. Her program covered information about reducing the airborne transmission of infectious diseases. Traci is located in the firm's Spokane office.
Traci started her presentation by referencing a book by David Quammen titled Spill Over. Since there are over 19 million cases of COVID-19, lots of it is about people and their individual behavior. What we are learning is that the size of the droplets are 0.12 um and can be transmitted through air and that toilets can be a risk of generating droplets. Recommendation: before flushing, close the lid.
How Can We Modify the Built Environment to Mitigate Risk? Traci talked about Airflow Patterns; diffuser adjustment/relocation; negative pressure spaces/source control; furniture layout/recirculating HEPA Filter Unite layout. Increase filtration level (MERV 13 rated or better where possible). Increase the amount of clean outside air being supplied; disinfection; toilet rooms and environmental conditions.
Purchasing MERV 13 Filters: You can purchase MERV 13 or higher filters at local hardware stores. Look for the MERV 13 rating. Look for a US Manufacturer. These filters usually cost around $10. MERV will capture all of the stuff coming through the system. Traci commented that electronic air filters can be just as good was well.
Residential COVID Room Exhaust: Position the fan to blow outward to form "negative pressure" in room to help protect the rest of the house. Cover the window screen beyond the fan face with clear packing tape and or clear plastic wrap to prevent back-flow.
Humidity: Traci also presented the results of several studies that showed how the humidity of a room can affect the dispersal and transmission of contagious viruses. The upshot is that when there is higher level of humidity in a given space the transmission of the viruses was significantly reduced. Some studies indicated that occupants in higher humidity environments tend to not get as sick as those that are in drier environments.
Conclusion: The public health benefits of enhanced ventilation far exceed the per occupant economic costs in U.S. cities. Even with conservative estimates, the increased productivity of an employee is over 150 times greater than the resulting energy costs. Environmental costs are also relatively minor, but should be offset by the incorporation of energy recovery systems, advanced ventilation strategies, and other green building design strategies. Traci has worked with Stephanie Taylor, MD., M.Arch, Harvard Medical School Incite Fellow and others.