Modification of “all-cause” daily mortality; PM10 association by city characteristics* across 20 cities in the United States, between 1989 and 2000
| City characteristics | Effect modifier coefficient† | % increase at the 25th centile‡ | % increase at the 75th centile‡ | |||||
|---|---|---|---|---|---|---|---|---|
| % | 95% CI | 1st quartile | % | 95% CI | 3rd quartile | % | 95% CI | |
| PM10, particulate matter of aero-diameter equal or less than 10 μm. | ||||||||
| *Effect modification by city characteristics was examined for the three day cumulative effect for all-cause mortality. | ||||||||
| †The estimates represent the coefficient of the interaction term for the tested modifier on the mortality-PM10 association. The estimates for the city effect modifiers are presented as percentage increase in mortality per 10 μg/m3 increase in PM10, per every unit increase in the modifier as shown in the table. The estimate for population density is presented as percent increase in mortality per each increment of 10 μg/m3 of PM10, per 1000 count/mile2. | ||||||||
| ‡The estimates are presented as percentage increase in mortality per 10 μg/m3 of PM10, for the 25th centile and 75th centile of the distribution of city effect modifiers. For population density, the estimates are presented as percentage increase in mortality per of 10 μg/m3 of PM10, for 1000 count/mile2 and 3000 count/mile2. | ||||||||
| §Significant at α = 0.05. | ||||||||
| % Central air conditioning | −0.13 | −1.42 to 1.15 | 24.8 | 0.45 | 0.17 to 0.72 | 56.1 | 0.41 | 0.11 to 0.70 |
| Population density (count/mile2) | 0.12§ | 0.04 to 0.20 | 1000 | 0.27 | 0.04 to 0.49 | 3000 | 0.51 | 0.38 to 0.63 |
| Age standardised mortality rate | −25.5 | −198.8 to 147.8 | 0.008 | 0.47 | 0.17 to 0.80 | 0.010 | 0.41 | 0.17 to 0.66 |
| % >65 years old | 0.05 | −0.01 to 0.11 | 10.3 | 0.34 | 0.11 to 0.58 | 14.3 | 0.53 | 0.33 to 0.74 |
| % >75 years old | 0.08 | −0.04 to 0.20 | 5.1 | 0.36 | 0.12 to 0.59 | 7.3 | 0.54 | 0.32 to 0.76 |
| % >85 years old | 0.22 | −0.28 to 0.71 | 1.3 | 0.37 | 0.13 to 0.62 | 1.8 | 0.49 | 0.27 to 0.72 |
| Daily minimum summer AT (°C) | ||||||||
| Mean | −0.01 | −0.09 to 0.06 | 22.3 | 0.45 | 0.16 to 0.74 | 24.7 | 0.41 | 0.09 to 0.73 |
| Variance | 0.41§ | 0.14 to 0.67 | 3.6 | 0.09 | −0.23 to 0.40 | 4.7 | 0.52 | 0.37 to 0.67 |
| Daily maximum winter AT (°C) | ||||||||
| Mean | −0.08§ | −0.14 to −0.03 | −2.9 | 0.59 | 0.43 to 0.75 | −0.8 | 0.41 | 0.25 to 0.58 |
| Variance | 0.10 | −0.16 to 0.36 | 4.4 | 0.40 | 0.17 to 0.62 | 5.5 | 0.51 | 0.25 to 0.76 |
| % of primary PM10 from traffic | 0.16§ | 0.06 to 0.26 | 2.4 | 0.15 | −0.11 to 0.42 | 4.4 | 0.46 | 0.31 to 0.61 |