Table 5.
The effect of time of day on indoor and outdoor PM2.5 concentrations (N = 96)
| Time of day | Median | Range | exp(β)a | 95 % CI |
|---|---|---|---|---|
| 10pm–2am | ||||
| indoor | 14.9 | 3.0, 117.5 | ref | ref |
| outdoor | 23.0 | 2.0, 202.3 | ref | ref |
| 2am–6am | ||||
| indoor | 8.4 | 1.2, 122.4 | 0.53 | 0.45, 0.61 |
| outdoor | 14.9 | 0.2, 193.1 | 0.60 | 0.52, 0.68 |
| 6am–10am | ||||
| indoor | 15.4 | 1.3, 716.8 | 0.92 | 0.76, 1.12 |
| outdoor | 15.9 | 0.7, 167.1 | 0.72 | 0.64, 0.82 |
| 10am–2pm | ||||
| indoor | 13.3 | 0.1, 201.6 | 0.85 | 0.68, 1.08 |
| outdoor | 11.1 | 0.1, 112.1 | 0.47 | 0.38, 0.58 |
| 2pm–6pm | ||||
| indoor | 14.3 | 0.4, 457.0 | 1.09 | 0.90, 1.32 |
| outdoor | 12.6 | 0.2, 106.2 | 0.51 | 0.43, 0.62 |
| 6pm–10pm | ||||
| indoor | 25.4 | 3.9, 374.5 | 2.01 | 1.73, 2.33 |
| outdoor | 21.2 | 1.7, 84.0 | 0.93 | 0.85, 1.02 |
Abbreviations: exp(β), exponentiated coefficient describing relationship between potential predictor and indoor air quality measure; CI, confidence interval; ref, reference category.
a
Time of day was included in analyses as a 6-level categorical variable.
b
Exponentiated coefficients from repeated measures analyses represent the ratio of geometric mean PM2.5, natural log-transformed in analyses, associated with time of day. 10pm–2am was used as the reference category.