Source: https://www.utoronto.ca/news/really-big-deal-u-t-s-colin-furness-why-ventilation-key-fighting-covid-19

As the weather turns colder and people move indoors, the University of Toronto’s Colin Furness is emphasizing the importance of proper ventilation to combat the spread of the virus that causes COVID-19.
The expert in infection control epidemiology and COVID-19 pandemic management says it’s well-established in the medical community that airborne transmission is major contributor to the spread SARS‑CoV‑2. But he notes that public health regulations have often been slow to catch up, leaving many businesses and other organizations with less-than-optimal safeguards.