Table 3.
PM2.5 Concentrations in Different Locations during the Study Period
| Location | Pre median, mean (SD), range |
During median, mean (SD), range |
Post median, mean (SD), range |
During – Pre | Post – During | ||
|---|---|---|---|---|---|---|---|
| Mean difference (95% CI) |
p-value | Mean difference (95% CI) |
p-value | ||||
| Outdoors | 53.0, 70.3 (53.2), 17–344 | 79.0, 90.1 (46.3), 19–268 | 100.0, 109.5 (55.8), 14–264 | 16.5 (10.0, 23.0) | <0.001 | 19.4 (12.4, 26.4) | <0.001 |
| Office A | 9.3, 9.6 (5.6), 2.8–21 | 38.3, 39.5 (17.4), 15–101 | 14.2, 17.3 (11.4), 0.8–73 | 29.9 (19.6, 40.1) | <0.001 | −22.1 (−26.5, −17.8) | <0.001 |
| Office B | 6.9, 6.6 (2.2), 1.5–9.8 | 5.5, 5.6 (3.1), 0.0–15 | 6.3, 7.4 (2.8), 2.6–18 | −0.99 (−2.18, 0.20) | 0.003 | 1.85 (1.05, 2.65) | <0.001 |
| Dorms | 7.9, 11.7 (8.2), 1.3–29 | 7.6, 15.8 (18.4), 0.0–72 | 14.6, 33.0 (27.1), 7.0–85 | 4.13 (−6.63, 14.9) | 0.95 | 17.1 (9.86, 24.4) | <0.001 |
| Dorms (Smoking) | 33.2, 46.0 (30.2), 22–156 | 39.8, 44.9 (32.2), 1.1–199 | 70.9, 58.5 (39.3), 3.1–136 | −1.12 (−19.2, 16.7) | 0.77 | 13.6 (−0.38, 27.6) | 0.11 |
| Intervention A Dorm | — | 38.4, 51.4 (31.3), 8.7–160 | 10.2, 19.0 (28.0), 3.0–142 | 39.8 (25.2, 54.3)a | <0.001a | −32.4 (−40.6, −24.2) | <0.001 |
Significance tests for between-period differences in PM2.5 concentrations were performed with Kruskal-Wallis non-parametric tests for global period effect and Dunn post-hoc tests for period-specific differences. Bolded p-values are < 0.05.
a
Since Group A subjects only moved from their dorms to the hotel at the beginning of the “During” period, the “During – Pre” comparison here is comparing the PM2.5 concentrations in dorms during the “Pre” period to the hotel during the “During” period. Indoor smoking did not occur among smokers in Intervention A Dorm, so “Dorms (Smoking)” only refers to Group B dorms in the during and post-intervention periods.