Air pollution and the incidence of ischaemic and haemorrhagic stroke in the South London Stroke Register: a case–cross-over analysis

Abstract

BackgroundFew European studies investigating associations between short-term exposure to air pollution and incident stroke have considered stroke subtypes. Using information from the South London Stroke Register for 2005–2012, we investigated associations between daily concentrations of gaseous and particulate air pollutants and incident stroke subtypes in an ethnically diverse area of London, UK.MethodsModelled daily pollutant concentrations based on a combination of measurements and dispersion modelling were linked at postcode level to incident stroke events stratified by haemorrhagic and ischaemic subtypes. The data were analysed using a time-stratified case–cross-over approach. Conditional logistic regression models included natural cubic splines for daily mean temperature and daily mean relative humidity, a binary term for public holidays and a sine–cosine annual cycle. Of primary interest were same day mean concentrations of particulate matter <2.5 and <10 µm in diameter (PM2.5, PM10), ozone (O3), nitrogen dioxide (NO2) and NO2+nitrogen oxide (NOX).ResultsOur analysis was based on 1758 incident strokes (1311 were ischaemic and 256 were haemorrhagic). We found no evidence of an association between all stroke or ischaemic stroke and same day exposure to PM2.5, PM10, O3, NO2 or NOX. For haemorrhagic stroke, we found a negative association with PM10 suggestive of a 14.6% (95% CI 0.7% to 26.5%) fall in risk per 10 µg/m3 increase in pollutant.ConclusionsUsing data from the South London Stroke Register, we found no evidence of a positive association between outdoor air pollution and incident stroke or its subtypes. These results, though in contrast to recent meta-analyses, are not inconsistent with the mixed findings of other UK studies.

Acute Effects of Particulate Air Pollution on Ischemic Stroke and Hemorrhagic Stroke Mortality

“…Nevertheless, we found a significant association between ischemic stroke death and PM 10 exposure, but not in hemorrhagic stroke. The studies of PM and hemorrhagic stroke were limited, and the outcomes were inconsistent ( 15 , 26 , 27 ). The mechanisms of hemorrhagic stroke and air pollution might be different from that of ischemic stroke and air pollution ( 23 ).…”

“…Moreover, few studies conducted in developing countries and distinguished the effects of PM on types of stroke ( 9 , 11 , 13 ). It is still not clear whether the effect of PM on ischemic stroke is the same with hemorrhagic stroke ( 12 , 14 , 15 ).…”

Interactive effects of changing stratospheric ozone and climate on tropospheric composition and air quality, and the consequences for human and ecosystem health

“…. 111 The authors also reported negative (but not significant ) associations between incidence of haemorrhagic stroke and an increment in concentration of 10 µg m -3 of PM10 (-14.6%, 95% CI 0.7-26.5%) and PM2.5 (-17.0%, 95% CI, 3.3-33.3).…”

Local- and regional-scale air pollution modelling (PM10) and exposure assessment for pregnancy trimesters, infancy, and childhood to age 15 years: Avon Longitudinal Study of Parents And Children (ALSPAC)

“…There was no PM 10 monitoring during all periods of pregnancy (1990–1992) and only partial coverage for periods of infancy for some of the cohort (1993-). We therefore used dispersion modelling ( Atkinson et al, 2015 ; Baiz et al, 2012 ; Charpin et al, 2009 ; Bellander et al, 2001 ; Butland et al, 2017 ; de Hoogh et al, 2014 ; Gong et al, 2017 ; Hansen et al, 2016 ; Korek et al, 2015 ; Nordling et al, 2008 ; Pirani et al, 2014 ; Van den Hooven et al, 2012 ; Schultz et al, 2016 ; Vinceti et al, 2016 ) to estimate population exposure. There are, however, only a few examples of using city/regional scale dispersion modelling for historic sub-annual exposure periods for particles ( Baiz et al, 2012 ; Nordling et al, 2008 ; Heck et al, 2013 ; Gong et al, 2017 ; Rahmalia et al, 2012 ; Sellier et al, 2014 ) due to the challenge of developing detailed inventories on sources and emissions of air pollution at different spatial scales (e.g.…”