Due to high levels of pollution found in air, soil and water in several parts of Delhi
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/ministry-bans-new-projects-citys-highly-polluted-areas
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/pollution
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/industrial-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/central-pollution-control-board-cpcb
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ministry-environment-and-forests-moef