COVID-19

COVID-19, like other respiratory viral infections, is primarily transmitted in small airborne particles that carry the virus and are emitted during all human activities related to respiration (1). Particles are emitted during speech, coughing, sneezing, exercise or also quiet breathing. The particles are small enough to remain airborne for prolonged periods, especially in poorly ventilated indoor environments, and be transmitted long distances. Hence, the presence of one or more people with COVID-19 in an indoor environment places all persons who share the air in that indoor space at risk of infection. Airborne transmission is the main mechanism of transmission of COVID-19, including ‘super spreader’ events (1,2). Despite confusing and sometimes misleading public health messages (3), preventive measures to mitigate the airborne transmission of COVID-19 became an important and effective part of the public health response to COVID. These measures included mask mandates, restrictions on indoor gathering, requirements for enhanced ventilation for indoor settings, and air filtration in health care facilities, schools, aged care facilities and other high risk indoor environments. However, these were essentially emergency measures. The most effective interventions to reduce the severity and cost of future pandemics involve continuously improving indoor air quality (IAQ) for all Australians, with co-benefits for reducing the health and economic burden of indoor air pollution more generally.