The city has always been polluted but the rate at which its level is increasing has turned menacing.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/kolkata-air-quality-fails-safety-test
[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/urban-air-quality
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rspm-pm-10
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/nitrogen-dioxide
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health-effects
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/central-pollution-control-board-cpcb
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-quality-monitoring