Localized air pollution, posing an environmental and health challenge, has been linked to the presence of 'heat islands' in Delhi — pockets which are significantly warmer than their surroundings.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/heat-islands-pose-serious-threat-delhiites-health
[2] http://admin.indiaenvironmentportal.org.in/category/author/jayashree-nandi
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-new-delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/beijing
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-quality-monitoring
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health-effects
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/oxides-nitrogen-nox
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/indian-institute-tropical-meteorology
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/congestion
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution