One big reason for the long spell of extreme cold weather in Delhi and many parts of North India this winter season -affecting road, rail and air traffic almost every day and claiming tens of lives
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/blame-pollution-cold-wave-north-india
[2] http://admin.indiaenvironmentportal.org.in/category/author/urmi-goswami
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/economic-times-new-delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cold-wave
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/scientists
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/indian-meteorological-department-imd
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi-pollution-control-committee-dpcc
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/central-road-research-institute-crri