Table 4.
Regression coefficients for various traffic counts controlled by wind speed (n=12)a.
Variable | Slope for traffic counts (SE) | P-value | Slope for wind speed (SE) | P-value |
---|---|---|---|---|
All vehicles | 0.018 (0.06) | 0.78 | −3.28 (1.52) | 0.06 |
Diesel-powered vehicles | 0.15 (0.68) | 0.83 | −3.44 (1.38) | 0.04 |
Non-diesel-powered vehicles | 0.019 (0.07) | 0.78 | −3.28 (1.53) | 0.06 |
Note: a multiple linear regression was used to predict the elevated average PM2.5 (μg/m3) during the recording time. Traffic counts and wind speed are two independent predictors.