It has taken a long time for air cleaning to be recognized as a powerful tool to reduce the risk of transmission of Covid-19, and it should be better adopted during this pandemic and to reduce cases of influenza. Ventilation and filtration are two proven techniques for physically removing viruses from the air, so people are exposed to fewer of them. Poor ventilation has been a factor in many coronavirus spreading events, such as the outbreak at a choir rehearsal in Skagit Valley, Wash.
There are simple ways to improve ventilation, such as opening windows and doors. A recent small study, which has yet to be peer-reviewed, showed that the amount of coronavirus in the air was significantly reduced when ventilation was dramatically increased by running an exhaust fan that removed the air. stale room, sucking outside air through an open window. Other effective options may require more effort. Ultraviolet treatment is another approach used in hospitals to kill viruses in the air. This technique could be more widely applied in crowded public areas, although it must be properly installed to be effective and avoid the risk of damage. The initial cost is higher than other approaches, but it is worth considering as part of a cost-benefit analysis of different technologies.
Increasing humidity can also be helpful in reducing transmission. The evidence is not as strong as for other tools, but some data shows that an air humidification in the range of 40 to 60% – but not more because it promotes mold growth – might help. In this range, some influenza viruses, the novel coronavirus and other viruses survive less well, and our immune response is stronger than when the air is drier. This effect is not yet fully understood and should be further investigated.
I have long believed, based on years of research, that the role of aerosols in the spread of many respiratory viruses is underestimated by the medical community. I hope Covid-19 has catalyzed a shift in thinking about the air we breathe. You wouldn’t want to drink a glass of water full of pathogens, chemicals, and dirt. Why should we put up with breathing contaminated air?
Some unknowns still remain: it is not clear to what extent respiratory virus transmission is attributed to inhalation of aerosols versus spraying large droplets versus contact with contaminated surfaces. How to develop this knowledge and design buildings to minimize disease transmission? This is a question that governments and scientists should be looking at.
It will be a challenge to rethink the design and operation of buildings to take into account air quality, but it is not insurmountable. At the turn of the 20th century, the proliferation and modernization of water and wastewater treatment systems helped make common water-borne diseases such as typhoid and cholera a rarity in the United States and Europe. . The results of investments in hydraulic infrastructure are considered one of the greatest public health achievements of the 20th century. Making air quality healthier as a means of reducing disease should be a public health goal for this century.
Linsey Marr is an engineering professor at Virginia Tech, where she studies the airborne transmission of viruses.