Table 3.
Baseline characteristics of participants exposed to quartile (Q1-Q4) daily average concentrations of non-methane hydrocarbons (NMHC)
| Variables | NMHC N = 246,844 |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Q1 N = 55,312 |
Q2 N = 75,581 |
Q3 N = 54,687 |
Q4 N = 61,264 |
p-value | ||||||
| n | % | n | % | N | % | n | % | |||
| Age | mean, SDa | 6.12 | 3.18 | 6.04 | 3.09 | 7.02 | 3.52 | 6.97 | 3.67 | < 0.001 |
| Boys | 28,693 | 51.9 | 39,338 | 52.1 | 27,917 | 51.1 | 31,308 | 51.1 | < 0.001 | |
| Monthly income (NTD)b | < 0.001 | |||||||||
| < 15,000 | 47,529 | 85.9 | 64,814 | 85.8 | 44,185 | 80.8 | 49,343 | 80.5 | ||
| 15,000 − 19,999 | 5766 | 10.4 | 8467 | 11.2 | 7931 | 14.5 | 8707 | 14.2 | ||
| ≥ 20,000 | 2017 | 3.65 | 2300 | 3.04 | 2571 | 4.70 | 3214 | 5.25 | ||
| Urbanization levelc | < 0.001 | |||||||||
| 1 (highest) | 10,156 | 18.4 | 19,922 | 26.4 | 25,416 | 46.5 | 26,333 | 43.0 | ||
| 2 | 16,372 | 29.6 | 26,062 | 34.5 | 15,707 | 28.7 | 21,044 | 34.4 | ||
| 3 | 8878 | 16.1 | 19,178 | 25.4 | 9417 | 17.2 | 9540 | 15.6 | ||
| 4 (lowest) | 19,906 | 36.0 | 10,419 | 13.8 | 4147 | 7.58 | 4347 | 7.10 | ||
| Outcome | ||||||||||
| Atopic dermatitis | 1046 | 1.89 | 1692 | 2.24 | 1878 | 3.43 | 2688 | 4.39 | < 0.001 | |
Chi-square test; aOne-way ANOVA; SD standard deviation
bMonthly income: New Taiwan Dollar (NTD), 1 NTD is equal to 0.03 USD
cUrbanization level: The urbanization level was categorized by the population density of the residential area into 4 levels, with level 1 as the most urbanized and level 4 as the least urbanized