Kids who Breathe More Pollution Have Lower Grades

A child plays near the Valero Oil Refinery in the Manchester
neighborhood of Houston, TX. (Source: Earthjustice)

The link between air pollution and increased respiratory disease in children has been well studied.  There are still questions, however, about how such pollution may impact a child's academic performance. While some studies have looked at the link between air pollution exposure and academic success, these studies have been limited by their resolution, primarily using school-level data which can miss the effects of individual factors, like socioeconomic status or parental education, on school performance.

A new study published in the journal Population Environment looks at this problem at the individual level, and demonstrates a link between exposure to air toxic pollution and a lowering of GPA when controlling for several factors also known to impact school performance.  The study used data from EPA’s National Air Toxics Assessment (NATA), an inventory which estimates concentration of air toxic pollutants, as well as household and school performance information gathered through mail surveys.  Even when controlling for a variety of factors (economic deprivation, mother’s education, age of mother at birth, race/ethnicity and mother’s English proficiency), seven of the eight NATA risk variables were significantly negatively correlated with a child’s GPA. In other words, all other things being equal, children exposed to higher doses of toxic air pollutants will have lower GPAs than their peers.  The online publication, Mother Jones, covered the study in its recent article “Kids Who Breathe More Pollution Have Lower Grades”

In general, the Mother Jones does a good job summarizing the main points of the study and conveying the conclusions of the research.  The final paragraph of the MJ article includes a quote from the study’s author, Sara Grineski: “The finding that there is a significant association between residential exposure to air toxins and GPA at the individual level is both novel and disturbing…these findings provide another piece of evidence that should inform advocacy for pollution reduction…”.  This really is the main point and conclusion of the journal article and MJ does a good job to leave the reader with that sentiment.

The MJ article, however, fails to discuss the limitations of the research. It is really difficult to estimate individual level exposure without direct monitoring and the study’s data sources leave a lot of room for error. The EPA’s assessment of air toxic concentration is based on calculation and modeling, meaning that it is likely a close, but not exact estimate of ambient air toxic concentration. Further, the study assumes that all children living within a census block experience the same exposure, which is also likely untrue.  Concentration at individual houses will be variable due to weather patterns, some children may spend less of their time at home, some may spend more of their time playing outside where they are exposed at higher rates, etc. While the study mentions these limitations, the Mother Jones article does not include information about the data used in the study. Without looking at the original article, the reader would likely assume that the data comes from direct pollution measurements and that exposure estimates for individual children are exact.

The article links to the MJ cover story about a growing body of research linking ultra-fine particle pollution to dementia and Alzheimer’s disease.  While this provides the reader more information about how pollution may impact student’s GPA, it also implies that the journal article demonstrates a clear link between air pollution and lowered neurological function. The journal article only shows that higher exposure is correlated to lower GPA. This could mean that breathing more pollution is directly worsening school performance by impacting cognitive function, but it also could mean that the children are missing more days of school due to other pollution-related illness. By framing this study in terms of the Alzheimer’s work, the MJ article draws a conclusion not demonstrated by the research.

While they don’t get all the nuance of the data, and perhaps go beyond what the study’s authors have proven, the MJ article does a good job presenting the information in an accessible and engaging way and highlights an important area of environmental justice research that ought to be better understood by the general public.

Journal Article: http://link.springer.com/article/10.1007%2Fs11111-015-0241-8

Mother Jones Article: http://www.motherjones.com/blue-marble/2015/08/pollution-lowers-gpa