Table 2

Odds ratios for current wheeze in secondary school children in relation to traffic activity near the child's school

TAI (in millions)		Prevalence sample				Case-control sample
TAI (in millions)		Sample (n)	Cases of wheeze(n (%))			OR^2-150 (95% CI) (n=27612)	Sample (n)	Cases of wheeze (n)	Adjusted OR^2-151 (95% CI) (n=5589)
Continuous TAI			p=0.95				p=0.93
Per 10 unit increase	27668	5253 (19.0)	1.00 (0.99 to 1.01)		5936	2799	1.00 (0.98 to 1.02)
Tertiles:			p=0.23				p=0.53
Low ⩽22	9732	1877 (19.3)	1		1937	910	1
Medium 23–31	10314	1980 (19.2)	0.99 (0.92 to 1.06)		2510	1206	1.03 (0.91 to 1.17)
High ⩾32	7622	1396 (18.3)	0.94 (0.87 to 1.01)		1439	683	0.96 (0.83 to 1.10)

↵2-150 Adjusted for age and sex only
↵2-151 Adjusted for age, sex, social class, and maternal smoking before child's fifth birthday.