Air pollution measurements collected in the greater Worcester, MA, area between 2003 and 2005 and their correlations
| Pollutant | |||
| PM2.5 mass, μg/m3 | PM2.5 filter absorbance, 1E-5 m−1 | NO2, μg/m3 | |
| Number of locations | 21 HSPH (256), | 21 HSPH (256) | 36 HSPH (523), |
| (measurements) | 2 MA DEP (66) | 3 MA DEP (143) | |
| Mean (SD) | |||
| Fall | 8.2 (3.2) | 0.55 (0.21) | 11.0 (5.3) |
| Spring | 8.5 (4.2) | 0.33 (0.11) | 8.9 (4.1) |
| Summer | 11.2 (4.1) | 0.45 (0.12) | 7.9 (4.2) |
| Winter | 9.2 (3.2) | 0.48 (0.22) | 13.4 (6.4) |
| Spearman correlation (p value) | |||
| PM2.5 filter absorbance | NO2 | ||
| PM2.5 mass, μg/m3 | 0.82 (<0.001) | 0.74 (<0.001) | |
| PM2.5 filter absorbance, 1E-5 m−1 | 0.85 (<0.001) | ||
HSPH, Harvard School of Public Health monitoring locations; MA DEP, Massachusetts Department of Environmental Protection monitoring locations.