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. 2013 Jul 8;110(32):12936–12941. doi: 10.1073/pnas.1300018110

Table 1.

Summary statistics

Variable South (1) North (2) Difference in means (3) Adjusted difference in means (4) P value (5)
Panel 1: Air pollution exposure at China's Disease Surveillance Points
 TSPs, µg/m3 354.7 551.6 196.8*** 199.5*** <0.001/0.002
 SO2, µg/m3 91.2 94.5 3.4 −3.1 0.812/0.903
 NOx, µg/m3 37.9 50.2 12.3*** −4.3 <0.001/0.468
Panel 2: Climate at the Disease Surveillance Points
 Heating degree days 2,876 6,220 3,344*** 482 <0.001/0.262
 Cooling degree days 2,050 1,141 −910*** −183 <0.001/0.371
Panel 3: Demographic features of China's Disease Surveillance Points
 Years of education 7.23 7.57 0.34 −0.65 0.187/0.171
 Share in manufacturing 0.14 0.11 −0.03 −0.15*** 0.202/0.002
 Share minority 0.11 0.05 −0.05 0.04 0.132/0.443
 Share urban 0.42 0.42 0.00 −0.20* 0.999/0.088
 Share tap water 0.50 0.51 0.02 −0.32** 0.821/0.035
 Rural, poor 0.21 0.23 0.01 −0.33* 0.879/0.09
 Rural, average income 0.34 0.33 0.00 0.24 0.979/0.308
 Rural, high income 0.21 0.19 −0.02 0.27 0.772/0.141
 Urban site 0.24 0.25 0.01 −0.19 0.859/0.241
 Predicted life expectancy 74.0 75.5 1.54*** −0.24 <0.001/0.811
 Actual life expectancy 74.0 75.5 1.55 −5.04** 0.158/0.044

The sample (n = 125) is restricted to DSP locations within 150 km of an air quality monitoring station. TSP (µg/m3) in the years 1981–2000 before the DSP period is used to calculate city-specific averages. Degree days are the deviation of each day’s average temperature from 65°F, averaged over the years 1981–2000 before the DSP period. The results in column (4) are adjusted for a cubic in degrees of latitude north of the Huai River boundary. Predicted life expectancy is calculated by OLS using all of the demographic and meteorological covariates shown. All results are weighted by the population at the DSP location. One DSP location is excluded due to invalid mortality data. *Significant at 10%, **significant at 5%, ***significant at 1%. Sources: China Disease Surveillance Points (1991–2000), China Environment Yearbook (1981–2000), and World Meteorological Association (1980–2000).