Not so long ago, elementary school teachers regulated classroom temperature by opening up a window or cracking a door when it got too hot. These days, of course, modern school buildings have fancier climate control systems that offer cooler temperatures at the push of a button, no outside air required.
Turns out, that might not be such a good thing.
According to a new study published in the journal Indoor Air, students in classrooms with high levels of fresh air stayed healthier and took fewer sick days. Those results come from researchers out of the Lawrence Berkeley National Laboratory, who analyzed ventilation rates in 162 elementary school classrooms over two years.
In California, where the study took place, building codes require schools to have the capacity to ventilate at 7.1 liters per second per person, or about 15 cubic feet per minute per person. But according to the researchers, more than half of the classrooms in their study didn't meet those standards. In the Central Valley, where extreme temperatures and portable classrooms make temperature control particularly difficult, 95 percent of classrooms didn't hit that mark.
Lower ventilation rates make it easier to control temperature and cut energy costs. But this study makes the case that they have downsides, too. The few classrooms surveyed that did meet ventilation standards had 3.4 percent fewer absences due to illness than their counterparts. "If you're in a building, you give off little bits of pollutants all the time," lead researcher Mark Mendell explains. "Those things get more and more concentrated. Outdoor air ends up diluting some of that."
Mendell can't say for certain why poor ventilation leads to poor health. But he speculates there might be irritants in classroom air that, over time, cause upper respiratory infections.
If every classroom in California met the state's ventilation standards, Mendell and his colleagues estimate the state would save $80 million in caregiver costs. School districts would also have access to an additional $33 million in attendance-linked funding every year. Compliance would cost a comparatively paltry $4 million in additional energy expenses.
Mendell says he hopes his research ignites a new debate about this easily overlooked topic. "It can help say 'see, there are reasons you have to think about providing better ventilation,'" he says. "No one's really made that case before."