Tracking Mumbai's pollution levels can be tricky given the fact that it's a windswept coastal city where the air is regularly cleared out by a seaborne breeze.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/malad-andheri-bkc-and-mazgaon-have-max-pollutants-air-study
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-mumbai
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/maharashtra
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/mumbai
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/pm-25
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rspm-pm-10
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/indian-institute-tropical-meteorology
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution