Two key points emerge from this table. First, there are large
differences in TSP exposure among Southern and Northern
Chinese residents, but not for other forms of air pollution (e.g.,
sulfur dioxide and nitrous oxides) owing to the greater distances
that they travel. Second, there are substantial differences in the
determinants of mortality rates (e.g., temperature and predicted
life expectancy) between the South and North, but adjustment
for the cubic polynomial in latitude greatly reduces these differences
and causes them to become statistically insignificant.
This finding supports the validity of the RD design and the 2SLS
approach to inferring the causal relationship between TSPs and
life expectancy.
Graphical Analysis. The paper’s