1,012 buses are older than 10 years while 127 are above 15 years old.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/outdated-rtc-buses-way-join-list-major-polluters
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/deccan-chronicle-telangana
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/telangana
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/state-pollution-control-board-spcb-0
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/buses