“We have known for a long time that increasing ventilation and enhancing the filtration systems of buildings reduces the transmission of influenza, tuberculosis, measles and even Sars-Cov-1 but it took some time for the experts to take on board that aerosol transmission of Covid-19 was also important,” he says.
The problem is that the ventilation rates of buildings have been reduced in the past 100 years, particularly so in recent decades. The air tightness of some energy efficient buildings has been prioritised to the extent that it could be unhealthy for people to spend long periods inside if the ventilation systems aren’t adequately maintained.
“We need to optimise our buildings for human health, safety and comfort without ignoring how buildings contribute to climate change,” he says. While waiting for upgrades to ventilation and filtration systems, portable air cleaners should be used so the indoor air is changed four to six times an hour, he recommends.