The World Health Organization (WHO), United States Environmental Protection Agency (EPA) and Center for Disease Control (CDC) have provided consistent messaging throughout the Coronavirus pandemic with recommendations to reduce transmission of the SARS-Cov-2 virus that leads to the COVID-19 disease, by means of; social distancing, personal protective equipment (PPE), good hygiene practices and [now] vaccination. Although these aforementioned recommendations remain consistent, the knowledge of inhalation route of aerosol transmission of the SARS-CoV-2 virus through indoor spaces has evolved more slowly, with vague recommendations that were initially challenging for facility managers to locate and decipher. As time progressed, the evolution of recommendations regarding building ventilation and how it has been presented to the general public has yielded more support for engineering controls for heating, ventilation and air-conditioning (HVAC) systems to mitigate the spread of spread of aerosols in occupied buildings. The promotion of the proposed controls for ventilation in buildings, outlined in this paper, is another step toward reducing the spread of COVID-19 and future aerosol spread viruses by means of ventilation. A layered approach which includes engineering controls in relation to building ventilation is now promoted by the CDC and EPA, showing growth in the understanding and dissemination of information to the public.

This paper has found that core recommendations provided for engineering controls in relation to building HVAC systems early in the pandemic (i.e., early 2020) did not vary greatly from those presented to the date of this publication (i.e., June 2021).