Association of individual air pollution exposures with adjusted Cox proportional hazards estimates for development of asthma by age 10 years
| Model and LHIN subregion | Hazard ratio (95% CI) | |
|---|---|---|
| Adjusted* | Adjusted† (Jan. 1, 2003–Mar. 31, 2009) n = 44 737 | |
| Model with no pollutants | ||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.7 (0.67–0.73) | 0.72 (0.67–0.77) |
| London–Middlesex | 0.61 (0.58–0.63) (Apr. 1, 1993–Mar. 31, 2009; n = 114 427) | 0.65 (0.61–0.69) |
| Model A: NO2 | ||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.72 (0.67–0.77) | 0.70 (0.62–0.81) |
| London–Middlesex | 0.63 (0.60–0.66) (Jan 1, 1996–Mar 31, 2009; n = 92 809) | 0.65 (0.60–0.69) |
| Model B: O3 | ||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.73 (0.69–0.77) | 0.72 (0.67–0.78) |
| London–Middlesex | 0.62 (0.59–0.65) (Jan. 1, 1996–Mar. 31, 2009; n = 92 809) | 0.65 (0.60–0.69) |
| Model C: SO2 | ||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.72 (0.68–0.75) | 0.80 (0.68–0.93) |
| London–Middlesex | 0.64 (0.59–0.69) (Apr. 1, 1993–Mar. 31, 2009; n = 114 427) | 0.81 (0.60–1.09) |
| Model D: PM2.5 | ||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.75 (0.69–0.82) | 0.75 (0.69–0.82) |
| London–Middlesex | 0.71 (0.63–0.81) (Jan 1, 2003–Mar 31, 2009; n = 44 737) | 0.71 (0.63–0.81) |
| Model E: all pollutants combined | ||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.79 (0.62–1.01) | 0.79 (0.62–1.01) |
| London–Middlesex | 0.89 (0.64–1.24) (Jan. 1, 2003–Mar. 31, 2009; n = 44 737) | 0.89 (0.64–1.24) |
Note: CI = confidence interval, LHIN = Local Health Integration Network, NO2 = nitrogen dioxide, O3 = ground-level ozone, PM2.5 = particulate matter 2.5 um or smaller, Ref. = reference category, SO2 = sulphur dioxide.
↵* Adjusted for maternal age, maternal asthma, sex, rural geography, neighbourhood material deprivation, neighbourhood ethnic concentration, cesarean delivery and fiscal year. The number of individuals per model is variable because the cohorts were restricted to children with no missing data for exposures to pollutants.
↵† Adjusted for all variables listed above, with sample size of cohorts restricted to children with available information on exposures to all pollutants.