When day cares in Helsinki installed air purifiers, kids stopped getting sick as often

Any parent who’s had to deal with a coughing or congested toddler knows how day cares can be a breeding ground for illness. But when a few day cares in Helsinki installed air purifiers, children’s illnesses dropped by 18%. E3 Excellence in Pandemic Response and Enterprise Solutions (E3), a project from Finnish universities and companies in the engineering, design, and air quality space that aims to control the spread of diseases, recently released those findings from a two-year study.  The research highlights the way indoor air quality affects our health—and continues to challenge the notion that viruses are mainly spread through droplets and direct contact. Scientists learned that same lesson early in the COVID-19 pandemic: In the first weeks of the spread of coronavirus infections, messaging focused on standing 6 feet apart and washing your hands. But researchers discovered the virus was spreading through airborne transmission, exhaled as thousands of tiny aerosols that float in the air and travel much farther than 6 feet.  Air Purifiers in Day Cares The E3 study looked at four different day care centers, all of which were equipped with ventilation systems and had good indoor air quality. For the first year of the study, portable air purifiers were set up in two of the day cares; they were moved to the other day cares in the second year. Researchers set out to double the amount of clean air in the room, and so implemented enough air purifiers to achieve that result. In total, 51 children were included in the study, with their illnesses tracked in electronic diaries over the two winters. (The day cares without air purifiers were the control groups, and researchers switched those groups halfway through to accommodate for how different diseases can spread through different day care groups.) Illnesses dropped 18%, with air purifiers as the only infection-mitigation strategy.  Ventilation systems or air purifiers affect only particles that travel through the air (rather than germs on surfaces, for example). The researchers stressed how their results show the high chance of airborne transmission for viruses, and how air purification alone could prevent the number of infections that result. The importance of indoor air quality The COVID-19 pandemic put more attention on indoor air quality, and the fact that respiratory diseases can spread through the air, not only through close contact (or when someone coughs or sneezes right on you). During the pandemic, multiple researchers highlighted the importance of monitoring—and regulating—our indoor air.  “We hope that it is accepted that not just [COVID-19] but all respiratory viruses and diseases likely go substantially or mostly through the air,” Jose-Luis Jimenez, a chemistry professor at the University of Colorado, Boulder, told Fast Company in 2021. “We really need to up our game and consider cleaning indoor air, removing viruses, and providing air that doesn’t have pathogens as a priority for our societies, much like providing [clean] water has been a priority.” Better indoor air does more than help prevent diseases; it can have a host of positive impacts. Previous research has linked better indoor air quality, thanks to air filtration systems, to improved test scores among students. And when CO2 builds up in rooms from people talking, that’s been linked to issues like drowsiness, headaches, and worse decision-making for office workers. Air purifiers have become a common tool for those living in regions affected by wildfire smoke, people who cook with gas stoves, or generally anyone who wants cleaner indoor air. Joseph G. Allen, director of the healthy buildings program at the Harvard T.H. Chan School of Public Health, has noted that pollution can be 5 to 10 times worse inside our homes than outside of them. “The focus right now is on infectious disease avoidance, and rightly so,” he wrote for Fast Company in 2021. “But there’s a lot more happening in your home that should catch your attention. Creating a safe and healthy home means paying attention to the air indoors.”