A team of scientists is calling for a ‘paradigm shift’ in regulations surrounding air quality in buildings to reduce the spread of airborne illnesses.
Published in Science, the analysis was carried out by 40 scientists including Cath Noakes, professor of Environmental Engineering for Buildings at Leeds University, and a member of SAGE.
According to the group, the shift required to ensure a ‘significantly reduced’ pathogen count in buildings is on the same scale as that of the response to Chadwick’s Sanitary Report in 1842, which led the UK government to organise clean water supplies and centralised sewage systems in cities.
Whilst public health regulations have concentrated on sanitation, drinking water and food safety, the risk from airborne pathogens such as influenza or Covid-19 has been ‘addressed fairly weakly, if at all’ in terms of regulations and standards for building design and operation pertaining to air quality, the scientists said.
Research during the Covid-19 pandemic has highlighted the role that aerosols play in spreading disease. When a person with a respiratory infection speaks, coughs or sneezes, particles are emitted from their nose and mouth and are carried in the air indoors, infecting other people.
Thought to be the dominant mode of transmission of many respiratory infections, the team said that there is strong evidence on disease transmission in various types of indoor spaces suggesting that the way we design, operate and maintain buildings influences transmission.
“Up to now, most of the efforts to prevent transmission of Covid-19 and other airborne respiratory diseases such as tuberculosis has focused on influencing individual behaviour such as mask-wearing, cough hygiene and hand-washing,” said Trish Greenhalgh, professor of Primary Health Care Sciences at Oxford University and one of the paper’s authors.
“These measures are still important, but they will be relatively ineffective in the indoor environment until we ensure that the air we inhale contains far fewer particles that have been exhaled by others in the room.”
Risk can be reduced through ventilation coupled with air disinfection and filtration systems, but almost no engineering-based measures to limit transmission have been employed in public buildings (excluding health care facilities) or transport infrastructure globally, researchers claim.
Current ventilation guidelines followed by architects and builders focus on reducing odours and carbon dioxide levels, and in maintaining thermal comfort. According to the scientists, installing ventilation and air-quality systems designed to remove airborne pathogens would only add around one per cent to the construction costs of a typical building.
The team is calling on the World Health Organisation to introduce indoor air quality guidelines to be extended to include airborne pathogens. This would mean designing and operating a building according to its purpose, the scientists wrote in their paper. For example, different standards would be enforced in a gym as opposed to a cinema.
“Windows should be opened and draughty rooms welcomed; if air is recycled it must be filtered and disinfected; and monitoring air quality — for example using CO2 monitors — should become commonplace,” Greenhalgh added.