The next hearing in the matter is on July 11, in which all states will have to present data on vehicular population.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/furnish-reports-most-polluted-areas-ngt-gives-three-weeks-time-states
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/national-green-trbunal-ngt
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/diesel
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/compensation