Table 2 Potential effect modifiers of traffic-concentration relationship
| Units | ||
|---|---|---|
| Home characteristics: | Obstructed from road | Yes/no |
| Obstructed from major road | Yes/no | |
| Sampling period characteristics: | Percent of hours downwind from major road | Percent (%) |
| Average windspeed during daytime sampling hours (6am–9pm) | m/s | |
| Percent daytime hours with still winds (< 2 m/s) | Percent (%) | |
| Percent of weekend sampling days | Percent (%) | |
| Floor (monitor height) | (Categorical: 1, 2, 3+) | |
| Snow during sampling period | Yes/no |