Strict emission standard but lenient enforcement is what marks the city's approach to pollution control.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/smoke-spewers-duck-green-law-no-one-stops-them-kolkata
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-kolkata
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/west-bengal
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/kolkata
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/lpg
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/pollution-under-control-certification