Individual level | | |
Age in years | 0.97 (0.95–1.00) | 1.00 (0.98–1.03) |
Smoking status | | |
Non-smokers (ref) | 1 | 1 |
With passive smoking | 1.11 (0.52-2.36) | 0.79 (0.41–1.54) |
Ex-smokers | 1.81 (1.13–2.91) | 1.08 (0.68–1.71) |
⩽ 10/day | 2.21 (1.27–3.87) | 1.81 (1.10–2.96) |
10–20/day | 2.56 (1.48–4.42) | 3.14 (1.95–5.04) |
> 20/day | 4.86 (2.68–8.82) | 4.81 (2.49–9.31) |
Respiratory infections before age 5 (yes) | 1.68 (1.05–2.71) | 1.12 (0.76–1.66) |
Rhinitis (yes) | 1.78 (1.27–2.51) | 2.00 (1.45–2.78) |
Social class | | |
Professional and managerial (ref) | 1 | 1 |
Other non-manual | 1.58 (1.02–2.46) | 1.46 (0.93–2.30) |
Skilled manual | 1.94 (1.20–3.14) | 0.92 (0.30–2.86) |
Semi/unskilled manual | 2.52 (1.51–4.19) | 2.13 (1.14–3.96) |
Unclassified | 1.47 (0.64–3.36) | 1.79 (1.03–3.08) |
Traffic | | |
None (ref) | 1 | 1 |
Seldom | 1.25 (0.82–1.93) | 1.23 (0.77–1.96) |
Frequent | 1.26 (0.82–1.95) | 1.46 (0.92–2.31) |
Constant | 0.88 (0.56–1.38) | 1.86 (1.24–2.77) |
Centre level† | | |
PM2.5 in μg/m3 | 0.97 (0.70–1.35) | 0.99 (0.85–1.17) |
Sulfur content in μg/m3 | 1.00 (0.70–1.44) | 1.00 (0.85–1.17) |
Odds ratio between % chronic phlegm v response rate | 0.88 (0.52–1.50) | 1.46 (1.07–1.99) |
Average educational level in years | 1.01 (0.59–1.75) | 0.98 (0.83–1.15) |
% Smokers | 0.36 (0.22–0.60) | 4.44 (0.89–22.1) |