Table.
Baseline characteristics of participants by quartiles of ambient NO2 exposure averaged from 2005 to 2008
|
NO2concentration, μg/m3 |
Total (n=512 709) | |||||
|---|---|---|---|---|---|---|
| ≤21·4 (n=131 343) | >21·4 to ≤29·8 (n=139 963) | >29·8 to ≤37·3 (n=118 094) | >37·3 (n=123 309) | |||
| Age, years | 51·7 (11·0) | 51·7 (10·8) | 51·6 (10·3) | 52·1 (10·5) | 52·0 (10·7) | |
| Sex | ||||||
| Female | 59·2% | 57·1% | 57·8% | 60·8% | 59·0% | |
| Male | 40·8% | 42·9% | 42·2% | 39·2% | 41·0% | |
| Urban area | 32·6% | 46·4% | 39·2% | 55·1% | 44·1% | |
| Household income, ¥/year | ||||||
| <20 000 | 71·8% | 63·2% | 61·4% | 60·9% | 57·3% | |
| 20 000–34 999 | 17·6% | 24·4% | 22·1% | 21·3% | 24·7% | |
| ≥35 000 | 10·6% | 12·4% | 16·5% | 17·8% | 18·0% | |
| Education | ||||||
| No formal school | 18·3% | 12·1% | 23·6% | 14·6% | 18·6% | |
| Primary school | 39·1% | 31·6% | 30·8% | 27·1% | 32·2% | |
| Middle school | 25·1% | 31·0% | 25·6% | 33·2% | 28·3% | |
| High school or above | 17·5% | 25·3% | 20·0% | 25·1% | 20·9% | |
| Smoking status | ||||||
| Never regular | 62·8% | 60·9% | 61·2% | 60·0% | 61·9% | |
| Occasional | 5·6% | 5·8% | 6·0% | 7·4% | 5·7% | |
| Ex-regular | 4·7% | 6·2% | 6·4% | 6·7% | 6·0% | |
| Current regular | 26·9% | 27·2% | 26·4% | 25·9% | 26·4% | |
| Alcohol intake | ||||||
| Never regular | 52·4% | 42·8% | 41·8% | 34·1% | 45·9% | |
| Ex-regular | 2·2% | 2·1% | 1·6% | 1·9% | 1·8% | |
| Occasional or seasonal | 28·8% | 33·4% | 36·0% | 37·1% | 31·8% | |
| Monthly | 2·3% | 3·5% | 3·6% | 4·0% | 3·4% | |
| Reduced intake | 2·4% | 2·6% | 2·1% | 2·5% | 2·3% | |
| Weekly | 11·9% | 15·7% | 14·8% | 20·3% | 14·8% | |
| Heating fuels | ||||||
| Always clean | 5·9% | 10·2% | 10·4% | 11·8% | 8·6% | |
| Solid to clean | 2·9% | 19·2% | 13·7% | 20·9% | 11·3% | |
| Always solid | 51·1% | 42·2% | 31·8% | 25·4% | 36·2% | |
| No heating | 35·3% | 22·8% | 38·5% | 35·2% | 38·9% | |
| Others | 4·8% | 5·6% | 5·6% | 6·7% | 5·0% | |
| Cooking fuels | ||||||
| Always clean | 11·3% | 19·5% | 16·3% | 19·1% | 17·0% | |
| Solid to clean | 15·5% | 20·2% | 17·9% | 23·1% | 20·5% | |
| Always solid | 47·4% | 35·4% | 38·2% | 32·1% | 36·0% | |
| No cooking | 22·5% | 20·8% | 23·3% | 20·3% | 22·2% | |
| Others | 3·3% | 4·1% | 4·3% | 5·4% | 4·3% | |
| Physical activity, MET-h/day | 21·1 (12·8) | 20·0 (12·0) | 22·7 (15·2) | 19·4 (15·1) | 21·1 (13·9) | |
| BMI, kg/m2 | 23 (3·2) | 23·7 (3·3) | 23·7 (3·5) | 24·3 (3·4) | 23·7 (3·4) | |
| Self-reported health status | ||||||
| Excellent | 12·2% | 18·4% | 18·7% | 22·6% | 17·6% | |
| Good | 24·5% | 24·8% | 30·3% | 25·7% | 28·1% | |
| Fair | 50·8% | 45·7% | 39·2% | 39·9% | 43·9% | |
| Poor | 12·5% | 11·1% | 11·8% | 11·8% | 10·4% | |
| PM2·5, μg/m3 | 55·2 (8·0) | 61·6 (3·8) | 64·1 (3·8) | 71·4 (9·2) | 62·9 (10·2) | |
| O3, μg/m3 | 75·4 (2·5) | 73·5 (6·5) | 75·2 (6·3) | 74·8 (8·9) | 76·0 (6·8) | |
| NO2, μg/m3 | 19·0 (3·0) | 25·5 (2·6) | 34·8 (1·6) | 41·1 (2·9) | 29·8 (9·5) | |
| Temperature, °C | 17·3 (5·4) | 14·5 (5·6) | 13·5 (4·4) | 13·7 (3·9) | 15·6 (5·1) | |
| Relative humidity, % | 72·0 (6·0) | 67·4 (5·4) | 65·4 (3·8) | 63·6 (6·5) | 67·4 (6·6) | |
Categorical variables are presented as percentages and continuous variables are presented as mean (SD). All means and percentages in the four NO2 groups were adjusted for age, sex, and study area, where appropriate. The cutoffs of quartiles of NO2 levels are rounded to the nearest one decimal place. NO2=nitrogen dioxide. MET-h/day=metabolic equivalent of task-hours per day. PM2·5=particulate matter with a diameter of <2·5 μm. O3=ozone.