POLLUTIONWHO's latest research reveals that Delhi has the highest levels of air pollution.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/indias-gas-chambers
[2] http://admin.indiaenvironmentportal.org.in/category/author/nidhi-jamwal
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/deccan-herald-bangalore
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health-effects
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/child-health
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/who
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/centre-science-and-environment-cse
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/diesel
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sunita-narain
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cng
[13] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[14] http://admin.indiaenvironmentportal.org.in/category/thesaurus/public-transport