SALT LAKE CITY — Researchers from the University of Utah believe poor air quality in Salt Lake County may have more far-reaching consequences on a child's education than previously believed.
Their study discovered that peaks in fine particulate matter called PM2.5 are linked to lower academic proficiency in third graders, adding to a growing body of research about air pollution's unforeseen effects, especially for society's most vulnerable populations.
The team published its full findings in the International Journal of Environmental Research and Public Health in the fall.
Sara Grineski, a professor at the University of Utah and co-author of the paper, emphasized that all students, no matter where they live in Salt Lake County, are hurt by the frequency of pollution-heavy days.
"We see this relationship between peak air pollution exposure and standardized test scores," she said. "We see that at schools where the pollution levels are lower, as well as at schools where the pollution levels are higher. And in fact, the relationship is even higher at schools where the pollution level is lower ... So I think the takeaway message from the complicated statistics is just that this is affecting kids at all schools in the county, and it's not just affecting kids where the pollution levels are higher."
To identify pollution peaks, the team analyzed 2016 data from the Environmental Protection Agency's Downscaler statistics, which track daily levels of PM2.5 around Salt Lake County.
A peak was defined as a 24-hour period that was in the year's 95th percentile or above for PM2.5 concentration, which computed to be 23 micrograms per cubic meter.
Younger students are still growing and breathe at a faster rate than adults — factors that put them at increased risk for things like air pollution.
"Air pollution really has an effect on (third grade students) physiologically," said graduate student and the study's lead author Casey Mullen.
The group reviewed student testing results from 156 public primary schools, using data from Utah's Student Assessment of Growth and Excellence tests in both math and English language arts. The researchers were looking for students that scored below proficiency levels.
The study also took into consideration each school's Title I status, proportion of ethnic minorities, neighborhood "context" and the percent of students on free or reduced meals — combining them into a social disadvantage variable.
With that data, they were able to use statistical models to isolate the impact of air pollution on proficiency levels from that of other factors.
Results showed chronic air pollution's effects were tightly tied to the social disadvantage variable.
"That relationship is so strong that when we start looking at school performance outcomes, right, when we look at the association between chronic air pollution and academic outcomes, that effect gets explained away by this social disadvantage variable," Grineski said.
Pollution peaks are also related to school disadvantage variables but not as strongly as chronic pollution. Even when all other variables were accounted for, peak pollution days still had a negative effect on testing scores.
And while all students were harmed by air pollution, not every student and not every school was subject to the same number of peak pollution days.
"We did an analysis, and we found that schools that have higher levels of this disadvantaged variables — so low-income, minority schools — are exposed to significantly higher levels of chronic particulate matter, and they are exposed to significantly greater numbers of peak air pollution days," Grineski said.
The researchers are also concerned by government agencies' current standards concerning air pollution and human safety.
The Environmental Protection Agency's health standard is at 35 micrograms per cubic meter, far higher than the 23 micrograms per cubic meter of PM2.5 that was in the 95th percentile of pollution in Salt Lake County in 2016.
"I think right now you see a pretty big disconnect between the academic literature and then the actual PM standard at the EPA, and so I think, maybe, moving forward into the next administration, we might see a tighter linkage between the science and the policy," Grineski said. "But, I mean, our study is one of probably thousands that makes a point that the PM standard is not health protective, and that it has to be lower."
"I do have hope that the weight of this evidence, as we've seen historically, will eventually drive the PM standard to a more health protective level. The sooner that happens, I think the better for the future of our country in terms of human capital."