Table 2.
The associations of chronic exposure to air pollutants and asthma severity stratified by age at asthma onset of 12 years
| All | Onset age > 12 years | Onset age ≤ 12 years | |||||
|---|---|---|---|---|---|---|---|
| (n = 645) | (n = 413) | (n = 232) | |||||
| Severity score | aOR | 95 % CI | aOR | 95 % CI | aOR | 95 % CI | P for interaction |
| PM10 > 66.0 μg/m3 | 1.37 | 0.93 – 2.00 | 1.74 | 1.13 – 2.70 | 0.87 | 0.49 – 1.55 | 0.03 |
| NO2 > 18.5 ppb | 1.15 | 0.77 – 1.72 | 1.29 | 0.81 – 2.04 | 0.92 | 0.49 – 1.71 | 0.28 |
| SO2 > 4.5 ppb | 1.30 | 0.86 – 1.95 | 1.52 | 0.95 – 2.43 | 1.00 | 0.54 – 1.83 | 0.19 |
| CO > 0.61 ppm | 1.13 | 0.75 – 1.69 | 1.21 | 0.76 – 1.92 | 1.03 | 0.56 – 1.90 | 0.54 |
aOR adjusted odds ratio; BMI body mass index; CI confidence interval
The odds ratios were adjusted with age, sex, BMI, education level and family income level. Those exposed to the pollutant concentrations lower than medians were used as reference groups. Numbers did not total 703 because of missing data. P values were for interaction terms between “air pollutant level by median” and “age at onset by 12 years”