The Geography of Economic Mobility and Air Pollution
Abstract
Intergenerational economic mobility varies widely within the U.S. Understanding the characteristics of places with high vs. low economic mobility has been the focus of a substantial body of recent research. In this visualization, I explore an additional correlate of economic mobility; ambient air pollution. Exposure to ambient air pollution has been shown to have negative long-term physical, cognitive, and economic impacts, with particularly acute effects on children. Using comprehensive satellite measures of air pollution over time, I show a striking geographic correlation between areas with relatively high levels of air pollution and relatively low levels of intergenerational economic mobility. This visualization provides supporting evidence that air pollution may play a role in maintaining the cycle of low economic mobility throughout many areas of the U.S. due to its many harmful effects.
Keywords
economic mobility, air pollution, inequality
Description
Intergenerational economic mobility within the U.S. is highly heterogeneous, with large differences in mobility between geographic regions, e.g. much of the Midwest and Southeast (Chetty et al. 2014). There are many distinguishing characteristics of places with high vs. low economic mobility, a number of which have been studied at length. One such characteristic that has escaped significant focus within the economic mobility literature is ambient air pollution. The harmful effects of ambient air pollution on long-term physical, cognitive, and economic outcomes have been widely studied, and have been shown to be particularly detrimental to children. Currie et al. (2011) show that air pollution from traffic congestion leads to increased risk of health complications, including low birth weight, among newborns which, in turn, has been shown to have significantly negative effects on future outcomes. Wodtke et al. (2022) show that exposure to ambient air pollution leads to decreased cognitive ability in children, lower educational achievement, and worse future economic outcomes. Additionally, Borgschulte et al. (2022) show that ambient air pollution leads to significant declines in labor market outcomes and productivity. These findings provide a strong basis to suspect that air pollution may serve as a mechanism for lower intergenerational economic mobility. To descriptively examine this potential mechanism, I map the relationship between ambient air pollution (fine particulate matter) and intergenerational economic mobility across the contiguous United States.
Using administrative census and tax records, Chetty et al. (2014) estimate economic mobility as a child’s expected income percentile in the national income distribution at age 30 if they were born to a family in the 25th percentile of the national income distribution. I then pair these measures of economic mobility with comprehensive measures of mean monthly particulate matter (PM 2.5) in µg/m³ across the contiguous U.S. (Donkelaar et al. 2021). All measures of economic mobility and air pollution are measured or aggregated at the commuting zone geographic level. Figure 1 displays economic mobility and mean air pollution quartiles (dividing economic mobility and air pollution measures into 4 even bins) for each commuting zone across the contiguous U.S.
The correlation between below-median air pollution quality and below-median economic mobility is striking, with large swatches of the southwest and midwest falling in both the quartile of the worst air pollution and the quartile of the worst economic mobility. Although there are some areas of the U.S. that fall into one extreme but not the other (e.g. bad air pollution but good economic mobility), these areas are the exception and not the rule. To quantify the strength of this correlation I estimate an OLS of the form \(y_i=\beta_1 + \beta_2x_i + \epsilon_i\) where \(i\) is the commuting zone, \(x\) is the mean annual PM 2.5 (in µg/m³), and \(y\) is the mean economic mobility (in income percentile ranks). The resulting coefficient of interest is \(\beta_2=\)-1.885 (p < 0.001), which can be interpreted as follows: on average, a one-µg/m³ increase in a commuting zone’s PM 2.5 pollution levels corresponds with a -1.885 decrease in economic mobility.
This figure brings to attention the striking relationship between ambient air pollution levels and economic mobility. It also provides supporting evidence for air pollution playing a role in the perpetuation of low economic mobility. Additionally, it motivates a deeper examination of air pollution as a potentially causal mechanism for economic mobility. Finally, it exemplifies the usage of cutting-edge, satellite-based measures of air pollution for gaining a comprehensive understanding of the relationship between air pollution and social systems.
Supplemental Material
Background materials on data and methods are available here.