An environment ministry official said that Delhi witnessed 56 good air days in January-June period in 2017, while this year the national capital had 65 such days.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/environment-ministry-launch-three-pilot-projects-tackle-air-pollution
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution-control
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/national-environmental-engineering-research-institute-neer
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ministry-environment-and-forests-moef
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-quality-monitoring