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

BMC Public Health

Table 1 Sample population from emergency department patients, Edmonton, Alberta, 2007-2009

	Control^*	Acute ischemic stroke^†	Hemorrhagic stroke^†	Transient ischemic attack^†	All strokes^†
N	37,724	2,224	736	1,736	4,696
Males, number (%)	24,382 (64.6)	1,128 (50.7)	404 (54.9)	792 (45.6)	2,324 (49.5)
Females, number (%)	13,341 (35.4)	1,096 (49.3)	332 (45.1)	944 (54.4)	2,372 (50.5)
Age, mean years (SD)	39.8 (16.9)	70.9 (15.0)	66.3 (17.4)	69.7 (14.6)	69.7 (15.3)
25^th Percentile NO₂, ppb	12.8	13.3	13.3	12.9	13.1
Median NO₂, ppb	14.9	15.4	15.4	15.1	15.3
75^th Percentile NO₂, ppb	17.8	17.8	18.0	17.2	17.5

^* Control group: Laceration, strain, sprain, patients, ICD-10 codes S01, S41, S51, S61, S71, S81, S91, S83, S93, S96.
^† Case group: Stroke patients, ICD-10 codes: transient ischemic attacks (G45x), acute ischemic attacks (I63x, I64), and hemorrhagic strokes (I60x, I61x, and I62x). Individual patients may have more than one type of stroke during study period.

ISSN: 1471-2458