Abstract
We examine the influence of exposure to fine particulate matter (PM 2.5) in ambient air over the previous 6 years on the average standardized test score performance in math, English language arts (ELA), and overall for sixth graders at a sample of California public school districts from 2015 through 2018. Public health research suggests that children exposed to localized air pollution may suffer from cognitive impairment during testing or chronic conditions such as asthma that could influence their academic performance. After controlling for the appropriate confounding variables, our findings indicate that a 1-unit increase (or an equivalent one-third increase in the standard deviation) in the average amount of particulate matter observed over the past 6 years in a school district reduces the average standardized test score by about 4%. In addition, a typical student in a California school district in the two highest quintiles of PM 2.5 exposure (controlling for other causal factors) exhibits standardized test scores closer to the fifth-grade equivalency level than the sixth. These results support the benefits of indoor air pollution mitigation as a likely cost-effective intervention to improve student academic success in primary school.
Why was the study done? Previous researchers found that local air pollution impacts children’s development, health, and learning ability and that exposure to fine particulate matter (PM 2.5) in ambient air can harm performance on standardized tests. This paper offers a novel approach by estimating the cumulative impact of average district-wide PM 2.5 exposure over the previous 6 years on California sixth graders’ math, English, and overall test scores. What did the researchers do? Our model connects average test scores from California public school districts to PM 2.5 concentrations measured by Census tract within the district. We include district demographic, socioeconomic, and geographic data to increase confidence that the effect is causal and minimize bias from variables correlated with PM 2.5. Data from multiple years enables the detection of long-term effects and allows us to control for district and year-specific effects. We also test the robustness of our findings to adjusted model designs and compare the effect size to prior studies. What did the researchers find? We find that an average school district in California that experiences a 1-unit increase in PM 2.5 concentration, holding other control variables constant, could expect overall grade equivalency for sixth graders to fall by about 4%. Dividing PM 2.5 exposure into five sequential levels, we find an increasingly negative effect that levels off when moving from the lowest to the highest levels. This cumulative effect is larger than prior measures of PM 2.5 impacts only on test day or over the school year. What do the findings mean? California’s primary school students have likely experienced a drop in standardized test score performance from sustained exposure to fine particulate matter. The effect size warrants policy consideration, as some paths to pollution mitigation (such as air filters in classrooms) may produce equitable and cost-effective test score gains.