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Table 2 Distribution of daily pollution concentrations from 2004 to 2010 and reported as median (25th–75th percentiles)

From: Upper gastrointestinal bleeding due to peptic ulcer disease is not associated with air pollution: a case-crossover study

Pollutant Overall Calgary Edmonton P-value
O3 (ppb) 21.7 (15.0–28.3) 19.3 (13.3–25.7) 23.7 (17.5–30.9) 0.2
SO2 (ppb) 1.0 (0.9–1.8) 1.0 (1.0–2.0) 1.1 (0.8–1.6) <0.001
CO (ppm) 0.3 (0.2–0.4) 0.4 (0.3–0.4) 0.3 (0.2–0.4) <0.001
NO2 (ppb) 12.7 (7.6–19.0) 17.3 (13.0–23.5) 7.9 (5.6–12.1) <0.001
PM2.5 (μg/m3) 5.3 (3.5–7.7) 6.0 (4.3–8.7) 4.6 (3.1–6.6) 0.2
PM10 (μg/m3) 18.1 (13.0–27.0) 22.0 (15.0–32.0) 15.8 (12.0–21.8) <0.001
  1. PPB parts per billion, PPM, parts per million, SO 2 sulfur dioxide, NO 2 nitrogen dioxide, CO carbon monoxide, O 3 ozone, PM 10 particulate matter with aerodynamic diameter of ≤10 μm, PM 2.5 particulate matters with aerodynamic diameter of ≤2.5 μm