Buses, trucks and autorickshaws the key culprits with their thick, black smoke
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/city-choking-vehicular-pollution
[2] http://admin.indiaenvironmentportal.org.in/category/author/anil-kumar-sastry
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/hindu-new-delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/karnataka
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/mangalore
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/pollution-under-control-certification