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Table 3 Adjusted odds ratios* for emergency department visits for asthma, patients of all ages, by season

From: Outdoor air pollution and emergency department visits for asthma among children and adults: A case-crossover study in northern Alberta, Canada

Pollutant Mean IQR All seasons Season
      October to March April to September
    OR 95% C.I. OR 95% C.I. OR 95% C.I.
SO2 Same day 3.0 0.97 0.95–0.98 0.96 0.93–0.98 0.98 0.95–1.00
  1-day lag   0.98 0.96–0.99 0.96 0.94–0.98 1.00 0.97–1.02
  3-day average   0.95 0.93–0.98 0.93 0.90–0.96 0.98 0.94–1.02
  5-day average   0.95 0.93–0.98 0.93 0.90–0.97 0.98 0.93–1.02
NO2 Same day 13.5 0.99 0.97–1.01 0.98 0.96–1.00 1.01 0.98–1.05
  1-day lag   1.01 0.99–1.03 0.99 0.97–1.01 1.07 1.03–1.10
  3-day average   1.01 0.99–1.03 0.98 0.95–1.00 1.09 1.04–1.13
  5-day average   1.03 1.00–1.05 0.98 0.95–1.01 1.14 1.09–1.20
CO Same day 0.5 0.99 0.98–1.00 0.98 0.97–0.99 1.04 1.01–1.08
  1-day lag   1.00 0.99–1.02 0.99 0.98–1.01 1.06 1.02–1.10
  3-day average   1.00 0.99–1.02 0.98 0.97–1.00 1.11 1.06–1.16
  5-day average   1.02 1.00–1.04 0.99 0.97–1.01 1.18 1.11–1.25
O3 (Max) Same day 18.0 1.02 1.00–1.04 1.02 0.98–1.05 1.04 1.01–1.07
  1-day lag   1.04 1.02–1.06 1.02 0.99–1.06 1.06 1.04–1.09
  3-day average   1.07 1.04–1.10 1.05 1.00–1.10 1.11 1.07–1.16
  5-day average   1.08 1.05–1.11 1.07 1.02–1.13 1.11 1.06–1.15
PM2.5 Same day 6.3 1.04 1.02–1.05 1.00 0.97–1.03 1.07 1.05–1.09
  1-day lag   1.01 1.00–1.03 0.99 0.97–1.02 1.03 1.01–1.05
  3-day average   1.04 1.02–1.06 0.99 0.96–1.03 1.08 1.05–1.11
  5-day average   1.04 1.01–1.06 0.98 0.94–1.02 1.08 1.05–1.12
PM10 Same day 16.0 1.04 1.02–1.06 1.00 0.98–1.03 1.07 1.04–1.09
  1-day lag   1.02 1.01–1.04 1.02 0.99–1.05 1.03 1.01–1.05
  3-day average   1.05 1.02–1.07 1.01 0.98–1.05 1.08 1.05–1.11
  5-day average   1.04 1.02–1.07 1.01 0.97–1.05 1.08 1.04–1.12
  1. *Odds ratios were calculated in relation to an increase in the interquartile range (IQR) of selected air pollutants and were adjusted for relative humidity and temperature, and daily number of visits for influenza (all ages combined).
  2. Particulate data were only available between January 1, 1998 and December 31, 2002