Table 4.

Adjusted odds ratios* for emergency department visits for asthma among individuals 2 – 4 years of age, by season

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	1.00	0.95–1.05	0.98	0.92–1.05	1.01	0.94–1.08
	1-day lag		0.95	0.90–1.00	0.93	0.87–0.99	0.95	0.89–1.03
	3-day average		0.97	0.90–1.04	0.93	0.85–1.02	0.99	0.89–1.11
	5-day average		0.96	0.89–1.04	0.91	0.82–1.02	0.99	0.87–1.12
NO2	Same day	13.5	1.00	0.95–1.05	0.96	0.91–1.02	1.08	0.99–1.18
	1-day lag		1.04	0.99–1.09	0.96	0.90–1.02	1.24	1.13–1.35
	3-day average		1.05	0.98–1.12	0.95	0.88–1.02	1.32	1.18–1.48
	5-day average		1.08	1.00–1.16	0.93	0.85–1.01	1.50	1.31–1.71
CO	Same day	0.5	0.99	0.95–1.03	0.97	0.93–1.01	1.06	0.97–1.15
	1-day lag		1.02	0.98–1.05	0.99	0.95–1.03	1.14	1.04–1.25
	3-day average		1.02	0.98–1.07	0.98	0.93–1.03	1.25	1.11–1.42
	5-day average		1.04	0.98–1.10	0.97	0.91–1.03	1.48	1.27–1.72
O3 (Max)	Same day	18.0	1.00	0.94–1.07	1.04	0.94–1.14	1.02	0.93–1.12
	1-day lag		1.03	0.97–1.10	1.08	0.98–1.18	1.05	0.97–1.14
	3-day average		1.06	0.97–1.14	1.12	0.99–1.27	1.10	0.98–1.22
	5-day average		1.06	0.97–1.15	1.16	1.01–1.34	1.06	0.94–1.19
PM2.5‡	Same day	6.3	1.02	0.96–1.07	1.02	0.94–1.11	1.06	0.99–1.14
	1-day lag		1.02	0.97–1.08	0.98	0.91–1.07	1.08	1.01–1.16
	3-day average		1.04	0.98–1.12	1.00	0.91–1.11	1.15	1.05–1.26
	5-day average		1.03	0.95–1.11	0.95	0.84–1.07	1.16	1.04–1.28
PM10‡	Same day	16.0	1.05	0.99–1.10	1.04	0.95–1.13	1.10	1.02–1.18
	1-day lag		1.03	0.97–1.08	1.00	0.92–1.09	1.07	1.00–1.15
	3-day average		1.07	1.00–1.14	1.02	0.92–1.13	1.14	1.04–1.26
	5-day average		1.07	0.99–1.16	1.00	0.89–1.13	1.16	1.05–1.28

*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).

^‡ Particulate data were only available between January 1, 1998 and December 31, 2002