Installing air filters in classrooms has surprisingly large educational benefits
Every winter, the problem of air pollution in Indian cities gets exacerbated with severe consequences on both short-term and long-term health of their residents. Whilst these consequences are bordering on survival issues, a new finding says improving air quality can in fact help societies prosper. This article in the Vox talks about a rumoured gas leak which prompted schools in a Los Angeles area to install air filters actually resulted in increasing test scores meaningfully and sustainably. In a research paper, NYU’s Michael Gilraine shows the results comparing test scores of schools in that area to those outside who did not experience any improvement in air quality. The difference is significant even comparable to the difference made by smaller class sizes.
“An emergency situation that turned out to be mostly a false alarm led a lot of schools in Los Angeles to install air filters, and something strange happened: Test scores went up. By a lot. And the gains were sustained in the subsequent year rather than fading away. That’s what NYU’s Michael Gilraine finds in a new working paper titled “Air Filters, Pollution, and Student Achievement” that looks at the surprising consequences of the Aliso Canyon gas leak in 2015. The impact of the air filters is strikingly large given what a simple change we’re talking about. The school district didn’t reengineer the school buildings or make dramatic education reforms; they just installed $700 commercially available filters that you could plug into any room in the country.
…Strikingly, however, air testing conducted around the time of the installation of the filters shows that the schools didn’t actually have abnormally high levels of the kinds of pollution that are normally associated with natural gas. Methane is lighter than air, and by the time the filters were installed — nearly three months after the leak — the extra pollution caused was all the way up in the sky and not affecting school buildings.
Consequently, the installation of the filters served not to remove extra contamination caused by the leak, but simply to clean up the normal amount of background indoor air pollution present in the Valley. That lets Gilraine estimate the difference in student performance for schools just inside the boundary compared to those just outside. He finds that math scores went up by 0.20 standard deviations and English scores by 0.18 standard deviations, and the results hold up even when you control for “detailed student demographics, including residential ZIP Code fixed effects that help control for a student’s exposure to pollution at home.”
For context, this is comparable in scale to some of the most optimistic studies on the potential benefits of smaller class sizes, with Alan Krueger finding that cutting class size by a third leads to a 0.22 standard deviation improvement in academic performance. Other studies find smaller or even negative effects (because adding teachers means bringing in less experienced or less effective ones), but even accepting the positive findings, it costs much more than $700 per classroom to achieve class size reductions of that scale.”