Table 2.
Average SB, air pollution concentrations, and other environmental variables in the last seven days before the survey.
| Freshman Cohort | 2013–2014 Cohort a | 2014–2015 Cohort b | 2015–2016 Cohort c | 2016–2017 Cohort d | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Survey Order | First | Second | First | Second | Third | First | Second | First | Second | |||||||||
| Dependent variables | ||||||||||||||||||
| SB | 65.03 | (20.23) *** | 65.23 | (19.91) *** | 64.99 | (18.96) *** | 62.99 | (19.47) *** | 55.43 | (19.99) *** | 62.39 | (18.95) *** | 60.79 | (21.66) *** | 65.75 | (19.98) *** | 64.43 | (20.33) *** |
| Air pollution measures | ||||||||||||||||||
| AQI | 53.29 | (24.15) | 79.14 | (23.92) | 218.14 | (141.55) * | 100.43 | (61.01) | 68.43 | (16.57) | 121.00 | (52.83) | 85.57 | (20.15) | 114.43 | (109.55) | 151.29 | (44.96) |
| PM2.5 (µg/m³) | 28.75 | (15.41) | 52.80 | (21.63) | 178.71 | (128.66) * | 69.59 | (51.96) | 36.06 | (11.76) | 89.24 | (43.36) * | 43.43 | (17.75) | 84.43 | (96.55) | 57.71 | (21.04) |
| PM10 (µg/m³) | 40.83 | (16.47) | 85.76 | (36.61) | 182.84 | (128.69) * | 97.81 | (62.46) | 79.93 | (34.05) | 104.16 | (46.56) | 103.57 | (48.42) | 118.29 | (125.32) | 114.00 | (32.21) |
| NO2 (µg/m³) | 34.48 | (10.40) | 45.73 | (10.56) | 70.77 | (28.60) ** | 37.51 | (12.73) | 33.20 | (8.63) | 55.57 | (7.93) ** | 32.43 | (13.39) | 57.14 | (38.85) | 35.71 | (8.67) |
| Environmental covariates | ||||||||||||||||||
| Temperature (°C) | 5.43 | (1.40) | 20.71 | (3.09) | 20.86 | (1.86) | 6.29 | (3.45) | 21.43 | (5.16) | 27.00 | (0.82) | 25.57 | (2.44) | (5.57) | (1.72) | 20.86 | (5.18) *** |
| Wind (m/s) | 3.57 | (0.67) | 3.14 | (0.24) | 3.43 | (0.73) | 3.79 | (0.91) | 3.01 | (0.19) | 3.00 | 0.00 | 3.14 | (0.24) | 3.29 | (0.06) | 3.15 | (0.24) |
| Rain (%) | 0.00 | (0.00) | 0.43 | (0.54) | 0.14 | (0.38) | 0.14 | (0.38) | 0.57 | (0.54) | 0.14 | (0.38) | 0.29 | (0.49) | 0.00 | (1.00) | 0.14 | (0.38) |
Notes: The results of SB using repeated measures one-way ANOVA analysis. Collection period of air pollution data. a 2013–2014 cohort: first (9–15 December 2013) and second (5–11 May 2014); b 2014–2015 cohort: first (6–12 October 2014), second (24 February–2 March 2015), and third (May 4–10, 2015); c 2015–2016 cohort: first (14–20 September 2015) and second (2–8 May 2016). d 2016–2017 cohort: first (21–27 November 2016) and second (15–21 May 2017) * p < 0.05. ** p < 0.01; *** p < 0.001. AQI: air quality index.