Table 2. Average school day exposure at baseline and with clean bus; improved HVAC strategies (μg/m3).
Average time-weighted daily exposures by pollutant for the baseline walking and baseline bussing scenarios are displayed; to the right of each baseline are the average time-weighted daily exposures for the clean bus strategy and improved HVAC strategy, respectively, followed by the percentage change from baseline for each strategy.
| Standard Bus Distant Baseline | Clean Bus Distant | % change after clean bus | Walk Local Baseline | Walk Local Improved HVAC* | % change after improved HVAC* | |
|---|---|---|---|---|---|---|
| benzene | 0.14 | 0.062 | −56% | 0.072 | -- | -- |
| CO | 96 | 43 | −56% | 46 | -- | -- |
| NOx | 24 | 11 | −56% | 15 | -- | -- |
| PM2.5 | 0.84 | 0.32 | −61% | 0.33 | 0.26 | −20% |
| OC | 0.31 | 0.12 | −62% | 0.11 | 0.085 | −21% |
| EC | 0.38 | 0.14 | −62% | 0.16 | 0.13 | −20% |
*
infiltration factors are fixed at 1.0 for CO, NOx (100% infiltration), whereas no infiltration factors for benzene were available from the literature, and thus, not modeled here.