natural concern related to the research design is that the
government used the Huai River as the demarcation line for
changes in other government policies related to public health, and
this would confound the estimates of TSPs on health. This possibility
is mitigated by the fact that the Huai River is not a border
used for administrative purposes. The Huai River follows the
January 0° average temperature line (Celsius), and this was in fact
the basis of its choice as a method to divide the country for free
heating. Further, local policies generally hew to administrative
boundaries associated with cities and provinces; indeed, the Huai
River cuts through several provinces. Nevertheless, we compiled
some additional variables on city-level policies that are plausibly
related to health from the China City Statistical Yearbook. We
examine whether there is any discontinuity in these variables at the