Table 2.
Summary statistics for air pollutant and meteorological variables
| Pollutant or meteorological variable (units)a | Minimum | Maximum | Mean ± St. dev | Mean as % of NAAQSb |
|---|---|---|---|---|
| PM2.5 (ug/m3) | 0.45 | 37.0 | 8.56 ± 5.4 | 71 % |
| NO2 (ppb) | 2.79 | 40.0 | 11.0 ± 5.0 | 21 % |
| SO2 (ppb) | 0.28 | 7.51 | 1.99 ± 0.91 | 7 % |
| Relative Humidity (%) | 22.4 | 93.9 | 68.7 ± 13.9 | -- |
| Temperature (°F) | 0.96 | 83.8 | 49.8 ± 17.1 | -- |
| Temperature (°C) | −17.2 | 28.8 | 9.89 ± −8.3 |
aAir pollutants: based on daily averages measured in Worcester, Ware and Springfield
Temperature and humidity: based on daily averages from Worcester Regional Airport
bRelevant USEPA National Ambient Air Quality Standards (NAAQS)
PM2.5 = 12 ug/m3 annual mean, averaged over 3 years
NO2 = 53 ppb annual mean
SO2 = 30 ppb annual mean (based on USEPA 1971 value, which was revoked in 2010 and replaced with a 1-h maximum)