Delhi crossed the 10 million mark of total vehicle registrations in 2017.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/worsening-congestion-spiralling-pollution-choke-delhi-says-study
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/asian-age-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/centre-science-and-environment-cse
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cars-and-congestion