The importance of clean air in classrooms—during the pandemic and beyond

The COVID-19 pandemic has brought about an increased focus on public health, particularly in school settings. From social distancing to testing regimes, education leaders are making serious changes to ensure that schools are safe for students, staff, and teachers. As the school experience continues to be reinvented, research points to an overlooked but potentially critical factor when thinking about reopening: air quality. While we have known for some time about the negative effects of air pollution on child health, recent evidence indicates that pollution also has detrimental effects on student learning. In turn, these relationships suggest the potential for some highly cost-effective interventions to raise student performance—and keep kids safer during the pandemic.

Evidence on the Effects of Pollution on Cognition

To date, most research has linked pollution to student learning using variation in outdoor air pollution. Researchers have documented significant declines in test scores when students take tests on days with high levels of particulate pollution. Another study compared students attending schools downwind relative to upwind of highways and found that increased air pollution from being downwind lowered test scores and raised behavioral incidents and absences. Similarly, in a recent working paper, a co-author and I use year-to-year variation in power production combined with wind direction to show that pollution from coal-fired power plants lower students’ test scores.

Several recent papers have been able to link indoor air quality to reduced cognitive performance. Research from chess tournaments found that a player’s probability of making an erroneous chess move (as determined by a chess engine) increased when particulate matter at the tournament venue was higher. An economist at the London School of Economics also linked indoor air quality to test performance. To do so, he collected air particulate readings in exam rooms at a university in London. He found that exam rooms at the university varied considerably in terms of air quality, and that students performed worse when they were assigned to exam rooms with higher levels of air pollution.

Reducing Children’s Pollution Exposure

Naturally, this evidence should spur policymakers to reduce children’s exposure to airborne pollutants. In general, the news has been positive on this front, with the average exposure to airborne pollutants in the United States declining by almost a third since 2000, according to satellite- and ground-based measures. These improvements have been driven by environmental regulations such as the Clean Air Act, along with the striking decline in coal use due to cheaper and cleaner alternatives, especially natural gas.

While the improvements in ambient air quality are commendable, children are also exposed to high levels of airborne pollutants indoors. Indoor air quality is a result of complex interactions between local meteorology, surrounding structures, and building characteristics (e.g., building ventilation, location of air intakes, etc.). Given this, indoor air pollution is highly spatially and temporally variable. For example, one of the key drivers of indoor air pollution is human movements causing the resuspension of settled dust, making it so that classroom air quality is worst when students enter/exit classes for recess or lunch. Researchers in London found that air quality inside classrooms was worse than the air quality outside. Given that students spend one-half of their waking time on weekdays at school, such evidence spotlights schools as a natural location to reduce students’ exposure to air pollution.

In that vein, one way to improve air quality inside classrooms is to upgrade aging schools. Research in this area has been promising, with one study in Texas looking at mold and ventilation remediation projects and finding that these renovations substantially raised test scores by about 0.1-0.15 of a standard deviation. These projects were costly, however, with the average remediation project costing between $300,000 and $500,000. Similar beneficial effects on test scores have been found using new school construction, although these entail even higher costs.

Source: Brookings