NGT imposed a ban on diesel vehicles of 2000 cc engine capacity and above as well as operation of 10-year-old diesel vehicles in six major cities of Kerala.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/kerala-hc-declines-intervene-ngt-order-imposing-ban-diesel-vehicles
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/kerala
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/diesel
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/national-green-trbunal-ngt
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/high-court
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/kochi
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/buses
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/public-transport
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution