Possible mechanisms explaining relation between stroke and air pollution 

Possible mechanisms explaining relation 

between stroke and air pollution

Several large cohort studies have shown a positive association between long term exposure to ambient air pollution and coronary and cerebrovascular events.^50 51 52 

Staffogia and colleagues showed that even in high income countries, where annual mean air pollution concentrations meet current international standards, small increases in PM_2.5 were associated with a 19% increase in the risk of cerebrovascular disease, including both ischaemic and haemorrhagic events.⁵¹ 

Long term exposures to PM_2.5 accelerate carotid atherosclerosis.⁵³ 

The underlying pathophysiological mechanisms after acute exposure to air pollutants in triggering stroke,

 however, remain unclear and might differ

 for haemorrhagic and ischaemic stroke.¹² 

Previous controlled exposure studies have shown that air pollution can adversely affect the vascular endothelium and increase activity of the sympathetic nervous system, resulting in vasoconstriction, increases in blood pressure, ischaemia, and risk of thrombosis.^5 8 54

 Indeed, even minor increases in PM_2.5 concentrations are associated with changes in cerebrovascular haemodynamics, including increased cerebrovascular resistance and reduced cerebral blood flow.⁵⁵ 

Another potentially important effect of air pollution that is pertinent to stroke is the risk of atrial arrhythmias, which could predispose to thromboembolic events. It is plausible that the association between short term exposure to air pollution and cerebrovascular events are a result of these important mechanistic pathways

Ref

 BMJ. 2015 Mar 24;350:h1295. doi: 10.1136/bmj.h1295

Short term exposure to air pollution and stroke: systematic review and meta-analysis

Anoop S V Shah 1,✉, Kuan Ken Lee 1, David A McAllister 2, Amanda Hunter 1, Harish Nair 2, William Whiteley 3, Jeremy P Langrish 1, David E Newby 1, Nicholas L Mills