Table 1. Relative contributions of each microenvironment to average school day exposure, by school attendance scenario.
Average time-weighted daily exposures for each pollutant are totaled in the bottom row of each Mode/School scenario block (in the row labeled “Total daily exposure, μg/m3”). The relative contributions of each pollutant, by microenvironment, are displayed as percentages in the columns above each total.
| School Attendance Scenario | benzene | CO | NOx | PM2.5 | OC | EC |
|---|---|---|---|---|---|---|
| Microenvironment (avg. hours spent) | ||||||
| Walk to Local School | ||||||
| AM Commute (.46) | 14% | 14% | 14% | 24% | 24% | 24% |
| Unload at School (.08) | 14% | 14% | 15% | 25% | 26% | 25% |
| In-School (8.1) | 57% | 57% | 57% | 29% | 29% | 28% |
| Load at School (.08) | 6% | 6% | 6% | 10% | 9% | 10% |
| PM Commute (.46) | 9% | 9% | 8% | 13% | 12% | 13% |
| Total daily exposure, μg/m3 (9.2) | 0.072 | 46 | 15 | 0.33 | 0.11 | 0.16 |
| Bus to Distant School | ||||||
| AM Commute (.52) | 48% | 48% | 51% | 57% | 59% | 57% |
| Unload at School (.08) | 4% | 4% | 4% | 5% | 5% | 4% |
| In-School (8.0) | 15% | 15% | 14% | 6% | 6% | 5% |
| Load at School (.08) | 2% | 2% | 2% | 2% | 2% | 2% |
| PM Commute (.52) | 31% | 31% | 29% | 31% | 29% | 31% |
| Total daily exposure, μg/m3 (9.2) | 0.14 | 96 | 24 | 0.84 | 0.31 | 0.38 |
| Drive to Distant School | ||||||
| AM Commute (.25) | 41% | 25% | 24% | 32% | 33% | 32% |
| Unload at School (.08) | 5% | 9% | 11% | 19% | 19% | 18% |
| In-School (8.5) | 23% | 43% | 46% | 24% | 24% | 23% |
| Load at School (.08) | 2% | 5% | 5% | 8% | 7% | 8% |
| PM Commute (.25) | 28% | 18% | 14% | 18% | 17% | 19% |
| Total daily exposure, μg/m3 (9.2) | 0.099 | 37 | 8.1 | 0.21 | 0.079 | 0.092 |