Table 1.
Air pollutants, climatic variables and traffic density during the study period
| Mean (SD) | Interquartile Range | |
| 1 hr maximum, O3 (ppb) | 86.5(34.4) | 48.0 |
| 1 hr maximum, NO2(ppb) | 68.6(25.8) | 34.0 |
| 24-hr average, PM2.5 (μg/m3) | 27.8(14.9) | 17.5 |
| PM2.5 absorbance (10 -5m-1)& | 10.3(4.9) | 8.5 |
| Temperature minimum, (°C) | 11.3(3.1) | 4.2 |
| Humidity minimum | 34.8(11.6) | 18.1 |
| Traffic density, hourly average† | ||
| A | 423.0(303.1, 1840.2) | 1537.1 |
| B | 30.1(13.1, 512.5) | 499.5 |
| C | 20.1(14.2, 144.5) | 130.3 |
| Distance from the main avenue to the child's residence(m) † | 147.0(67.9, 279.9) | 212.0♣ |
† Median (Q25, Q75). Definition: Standard Deviation (SD). A: Private cars (Gasoline); B: Small buses for public transportation (Gasoline or natural gas); C: School buses, other buses, pick up trucks and heavy trucks (Diesel); Ozone(O3), Nitrogen dioxide(NO2) and particles less than 2.5 μg/m3 in diameter(PM2.5),
&Light absorption in inverse meters.
♣ 95% of the children lived less than 500 m from the main avenue