Table 2.
Description of joint exposures
| The 2nd survey | NOx at workplace address (μg/m3) | Time outdoor in traffic/day (self-reported) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| total | 0-8 | 8-11 | 11-14 | 14-19 | > 19 | Total | 0-30 min | 30-1 h | 1-2 h | > 2 h | ||
| NOx at residential address (μg/m3) | 0-8 | 770 | 412(53.5%) | 78(10.1%) | 132(17.1%) | 60(7.8%) | 88(11.4%) | 770 | 159(20.6%) | 306(39.7%) | 188(24.4%) | 117(15.2%) |
| 8-11 | 210 | 30(14.3%) | 44(21.0%) | 59(28.1%) | 32(15.2%) | 45(21.4%) | 210 | 34(16.2%) | 87(41.4%) | 55(26.2%) | 34(16.2%) | |
| 11-14 | 210 | 13(6.2%) | 15(7.1%) | 102(48.6%) | 26(12.4%) | 54(25.7%) | 210 | 41(19.5%) | 88(41.9%) | 65(31.0%) | 16(7.6%) | |
| 14-19 | 161 | 4(2.5%) | 7(4.3%) | 38(23.6%) | 39(24.2%) | 73(45.3%) | 161 | 29(18.0%) | 65(40.4%) | 41(25.5%) | 26(16.1%) | |
| > 19 | 137 | 9(6.6%) | 4(2.9%) | 18(13.1%) | 26(19.0%) | 80(58.4%) | 137 | 20(14.6%) | 53(38.7%) | 37(27.0%) | 27(19.7%) | |
Percentage within row total. Exposure to residential traffic was predictive of exposure at workplace address, but less predictive of time spent outdoor in traffic. The first row shows that of those who live at a residential address with 0-8 ug NOx/m3, 53.5% also have a workplace address with 0-8 ug NOx/m3 and 20.6% spend 0-30 min outdoor in traffic/day.