A case-control study of medium-term exposure to ambient nitrogen dioxide pollution and hospitalization for stroke

BMC Public Health

Table 3 NO ₂ exposure (ppb) and smoker type, Edmonton, Alberta (Canadian Community Health Survey data, 2001, 2003, 2005, 2007)

			p-value for least significant difference
	n (%)	Mean NO₂(SD)	Daily	Occasional	Former
Daily	1,249 (20.9)	15.70 (3.24)
Occasional	283 (4.7)	15.52 (3.63)	0.40
Former	2,127 (35.6)	15.42 (3.29)	0.02	0.63
Never	2,308 (38.6)	15.23 (3.19)	<0.001	0.16	0.05

ISSN: 1471-2458