It is long known that air pollution causes serious health risks and can trigger fatal heart attacks and strokes.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/air-pollution-linked-heart-attack-stroke
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/ndtv
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/heart-diseases
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rspm-pm-10
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/pm-25
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/centre-science-and-environment-cse