Third, not only are the coefficients measuring the effect of pollution larger for low SES children, but these children are also exposed to considerably higher levels of pollution. As a result, they suffer greater harm from pollution, and higher pollution levels explain roughly 4% of the gap in asthma rates. Although there are many remaining factors for explaining this gap, this suggests that pollution is one potential mechanism for the well-known relationship between SES and health -- poorer families are unable to afford to live in cleaner areas, and their children's health suffers as a result. .
