Descriptive statistics for environmental variables, Boston, Massachusetts, USA, between 1998 and 2002
| Parameter (units; all are 24 h means) | Number of observations | Arithmetic mean (SD) | Range | Interquartile range |
|---|---|---|---|---|
| AT, apparent temperature; BC, black carbon; PM2.5, particles <2.5 μm in aerodynamic diameter, known as fine particles; SO42−, sulphate. | ||||
| *Particulate matter <2.5 μm in aerodynamic diameter measured by the Upright & Patashnik Tapered Element Oscillating Microbalance sampler. | ||||
| †BC measured by aethalometer (Magee Scientific). | ||||
| ‡SO42− measured by the Harvard Annular Denuder System or by ion chromatography. | ||||
| AT (°C) | 92 | 7.1 (10.0) | (−7.9, 33.1) | 16.5 |
| PM2.5* (μg/m3) | 92 | 11.4 (5.9) | (0.07, 33.7) | 7.6 |
| BC† (μg/m3) | 92 | 1.1 (0.8) | (0.2, 5.8) | 0.6 |
| SO42−‡ (μg/m3) | 59 | 3.0 (2.0) | (0.5, 9.6) | 2.2 |