A lot of confusion seems to exist over what really contributes to air pollution, particularly PM2.5 (fine, respirable particles) from the transport sector or from vehicles in Delhi.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/what%E2%80%99s-fouling-air-data-puzzling-govt
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[6] http://admin.indiaenvironmentportal.org.in/thesaurus/national-green-tribunal-ngt
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/indian-institute-tropical-meteorology
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/centre-science-and-environment-cse
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi-pollution-control-committee-dpcc
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health-effects
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rspm-pm-10