Table 4. Land use regression (LUR) covariates and model fits for inversion-focused and 24-h black carbon (BC).
|
LUR Model |
|||
|---|---|---|---|
| Covariates | β (P-value) | IQR conc. increasea | Seq R2 b |
| Inversion focused summer BC (abs) c | |||
| Intercept | 2.18 (0.11) | — | — |
| Weekly reference BC | 2.53 (0.0007) | — | 0.26 |
| Land use (industry) at 750 m | 3.0 × 10−6 (0.01) | 0.41 | 0.57 |
| Elevation at 1000 m | −0.009 (0.01) | −0.58 | 0.64 |
| Inversion focused winter BC (abs) | |||
| Intercept | 3.10 (0.12) | — | — |
| Weekly reference BC | 0.60 (0.82) | — | 0.04 |
| Land use (industry) at 750 m | 1.9 × 10−6 (0.0006) | 0.26 | 0.42 |
| Signaled intersections within 500 m | 0.05 (0.01) | 0.14 | 0.60 |
| Elevation at 1000 m | −0.005 (0.02) | −0.32 | 0.67 |
| Wind speed (m/s) | −0.30 (0.001) | −0.33 | 0.76 |
| 24-H summer BC (abs) | |||
| Intercept | −0.31 (0.36) | — | — |
| Weekly reference BC | 1.55 (0.01) | — | 0.12 |
| IDW of PM2.5 emissions | 0.36 (<0.0001) | 0.15 | 0.52 |
| Land use (Com+Ind) at 200 m | 4.5 × 10−6 (<0.0001) | 0.13 | 0.64 |
| Wind direction | |||
| Blowing from NW/W | 0.25 (0.001) | 0.25 | — |
| Blowing from SW/S | — | — | 0.74 |
| 24-H winter BC (abs) | |||
| Intercept | −0.09 (0.56) | — | — |
| Weekly reference BC | 1.31 (<0.0001) | — | 0.28 |
| IDW of PM2.5 emissions | 0.38 (0.001) | 0.16 | 0.61 |
| Land use (industry) at 750 m | 1.0 × 10−6 (0.02) | 0.14 | 0.67 |
a
IQR concentration increase=β × IQR of source indicator.
b
Seq R2 is the sequential model fit for each additional term incorporated into the model.
c
One influential point removed for LUR modeling. Bold values are the percentages of explained pollutant variability according to final LUR models.