Table 3.
Subset analysis of risk of death associated with exposure to air pollution
| Pollutant by subset | No | Mortality hazard ratio (95% CI) | ||
|---|---|---|---|---|
| Natural deaths | Cardiovascular disease | Respiratory disease | ||
| PM2.5 | ||||
| Full dataset | 325 367 | 1.130 (1.106 to 1.155) | 1.135 (1.095 to 1.176) | 1.054 (0.961 to 1.156) |
| Pollution level (µg/m3): | ||||
| <25 | 325 339 | 1.131 (1.107 to 1.156) | 1.135 (1.096 to 1.176) | 1.050 (0.957 to 1.152) |
| <20 | 316 540 | 1.138 (1.113 to 1.164) | 1.141 (1.101 to 1.183) | 1.071 (0.975 to 1.177) |
| <15 | 151 250 | 1.257 (1.193 to 1.324) | 1.276 (1.167 to 1.397) | 1.322 (1.075 to 1.625) |
| <12 | 52 528 | 1.296 (1.140 to 1.474) | 1.238 (0.999 to 1.535) | 1.417 (0.849 to 2.365) |
| <10 | 25 422 | 1.146 (0.931 to 1.410) | 0.863 (0.618 to 1.205) | 1.489 (0.622 to 3.564) |
| Nitrogen dioxide | ||||
| Full dataset | 325 367 | 1.086 (1.070 to 1.102) | 1.089 (1.060 to 1.120) | 1.101 (1.038 to 1.168) |
| Pollution level (µg/m3): | ||||
| <40 | 310 643 | 1.101 (1.083 to 1.119) | 1.104 (1.071 to 1.137) | 1.099 (1.030 to 1.173) |
| <30 | 247 039 | 1.114 (1.088 to 1.140) | 1.117 (1.074 to 1.161) | 1.049 (0.953 to 1.154) |
| <20 | 88 510 | 1.099 (1.033 to 1.170) | 1.171 (1.052 to 1.303) | 1.044 (0.809 to 1.347) |
| Black carbon | ||||
| Full dataset | 325 367 | 1.081 (1.065 to 1.098) | 1.085 (1.055 to 1.116) | 1.084 (1.020 to 1.151) |
| Pollution level (×10−5/m): | ||||
| <3 | 324 757 | 1.084 (1.067 to 1.101) | 1.087 (1.056 to 1.119) | 1.085 (1.021 to 1.154) |
| <2.5 | 320 632 | 1.091 (1.074 to 1.109) | 1.090 (1.058 to 1.123) | 1.100 (1.034 to 1.171) |
| <2 | 296 371 | 1.107 (1.087 to 1.128) | 1.107 (1.070 to 1.145) | 1.119 (1.044 to 1.200) |
| <1.5 | 142 032 | 1.125 (1.086 to 1.165) | 1.150 (1.072 to 1.234) | 1.127 (0.990 to 1.284) |
| <1 | 35 406 | 1.041 (0.942 to 1.150) | 0.895 (0.738 to 1.086) | 1.186 (0.798 to 1.763) |
| Ozone | ||||
| Full dataset | 325 367 | 0.896 (0.878 to 0.914) | 0.887 (0.854 to 0.922) | 0.890 (0.821 to 0.966) |
| Pollution level (µg/m3): | ||||
| <120 | 325 367 | 0.896 (0.878 to 0.914) | 0.887 (0.854 to 0.922) | 0.890 (0.821 to 0.966) |
| <100 | 320 522 | 0.891 (0.872 to 0.910) | 0.880 (0.846 to 0.915) | 0.891 (0.820 to 0.969) |
| <80 | 98 840 | 0.979 (0.940 to 1.018) | 1.021 (0.938 to 1.111) | 0.890 (0.772 to 1.025) |
PM2.5=fine particulate matter with an aerodynamic diameter of <2.5 µm.
Hazard ratios (95% confidence intervals) from the main linear model (model 3) presented for the following increments: PM2.5 5 µg/m3, nitrogen dioxide 10 µg/m3, black carbon 0.5×10−5/m, and ozone 10 µg/m3. These increments were chosen to reflect contrast in exposure for the pollutants, in accordance with the ESCAPE study. Main model adjusted for cohort or subcohort, age, sex, year of baseline visit, smoking status (current, former, never), smoking duration (years), smoking intensity (cigarettes/day, both linear and quadratic terms), body mass index ( <18.5, 18.5-24.9, 25-29.9, >30), marital status (single, married or cohabiting, divorced or separated, widowed), employment status (yes or no), and 2001 small area level mean income.