Links:
[1] http://admin.indiaenvironmentportal.org.in/news/natural-gas-cleaner-answer-pollution
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/natural-gas
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/carbon-monoxide
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/nitrogen-dioxide
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution-control