Mothers within 10 km of a monitor are almost a year younger on average than the sample mean.
It is striking that mothers within 10 km of a monitor are also much more likely to be African American or Hispanic and have half a year less education on average compared to the full sample.
They are also less likely to be married, but only slightly more likely to smoke than mothers who live further away from monitors.
Furthermore, census tracts near monitors are lower income and have a higher fraction of poor inhabitants than further census tracts.
These patterns are consistent with residential sorting based on air quality: monitors are generally located in more polluted areas, and the characteristics of those closer to the monitors are generally worse than those farther from the
monitors.