Countless studies and health reports have discussed the dangers of smoking--a nasty habit that can drastically increase the risk of lung cancer and other serious health issues.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/tobacco-smoke-increases-risk-oral-hpv-cancers
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/science-world-report
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/tobacco
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/smoking
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cancer
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/lung-cancer