Stroke and Long-Term Exposure to Outdoor Air Pollution From Nitrogen Dioxide

Abstract

Background and Purpose-Years of exposure to tobacco smoke substantially increase the risk for stroke. Whether long-term exposure to outdoor air pollution can lead to stroke is not yet established. We examined the association between long-term exposure to traffic-related air pollution and incident and fatal stroke in a prospective cohort study. Methods-We followed 57 053 participants of the Danish Diet, Cancer and Health cohort in the Hospital DischargeRegister for the first-ever hospital admission for stroke (incident stroke) between baseline (1993-1997) and 2006 and defined fatal strokes as death within 30 days of admission. We associated the estimated mean levels of nitrogen dioxide at residential addresses since 1971 to incident and fatal stroke by Cox regression analyses and examined the effects by stroke subtypes: ischemic, hemorrhagic, and nonspecified stroke. Results-Over a mean follow-up of 9.8 years of 52 215 eligible subjects, there were 1984 (3.8%) first-ever (incident) hospital admissions for stroke of whom 142 (7.2%) died within 30 days. We detected borderline significant associations between mean nitrogen dioxide levels at residence since 1971 and incident stroke (hazard ratio, 1.05; 95% CI, 0.99 -1.11, per interquartile range increase) and stroke hospitalization followed by death within 30 days (1.22; 1.00 -1.50). The associations were strongest for nonspecified and ischemic strokes, whereas no association was detected with hemorrhagic stroke. Conclusions-Long-term exposure to traffic-related air pollution may contribute to the development of ischemic but not hemorrhagic stroke, especially severe ischemic strokes leading to death within 30 days. (Stroke. 2012;43:320-325.)

Estimation of nitrogen oxides emissions from petrol and diesel passenger cars by means of on-board monitoring: Effect of vehicle speed, vehicle technology, engine type on emission rates

“…Current scientific evidence links short-term NO 2 exposures, ranging from 30 min to 24 h with adverse respiratory effects including airway inflammation in healthy people and increased respiratory symptoms in people with asthma. It also contributes to cardiovascular diseases, adverse birth outcomes, premature death and cancer (Andersen et al, 2012;Beelen et al, 2008;Kan and Jia, 2003;Kan et al, 2009;Michiels et al, 2012;Qian et al, 2007;Villeneuve et al, 2012;Yorifuji et al, 2013;Yu et al, 2013).…”

Air pollutants and hospital admissions due to stroke

“…Moreover, exposure to nitrogen dioxide was associated with admissions, denoting a more severe picture in a prospective cohort study (Andersen et al, 2012). The study identified significant associations between NO 2 exposure and stroke incidence and also fatal stroke during a follow-up of about 10 years.…”

Health effects of long-term exposure to air pollution: An overview of major respiratory and cardiovascular diseases and diabetes

“…None of the studies [53,[55][56][57][58] distinguished between ischemic and hemorrhagic stroke. A case-control study of ischemic stroke hospitalizations in Sweden failed to detect associations with air pollution [59], whereas a recent cohort study, the first with data on both stroke types, reported significant associations with the ischemic but none with hemorrhagic stroke [60].…”

“…The current evidence is conflicting [53][54][55][56][57][58][59][60]. A cohort of American women showed an association between air pollution and stroke incidence [53], whereas an American [55] and Norwegian [56] cohorts failed to detect association with stroke mortality.…”