Chandigarh has 9.75 lakh registered vehicles for a population of 10.55 lakh. Apart from this, the floating population of vehicles is around 1 lakh.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/level-rspm-city-air-above-permissible-limit-shows-data
[2] http://admin.indiaenvironmentportal.org.in/category/author/tanbir-dhaliwal
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-chandigarh
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/punjab
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/chandigarh
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/oxides-nitrogen-nox
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-quality-standards
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health-effects