Concentration levels of harmful particulate matter were on average three times the standards.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/air-quality-get-worse-diwali
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/hindu-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/diwali
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/festival
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/pm-25
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rspm-pm-10
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-quality-monitoring
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/centre-science-and-environment-cse
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi-pollution-control-committee-dpcc