There's new evidence that exposure to exhaust from diesel engines increases the risk of lung cancer.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/study-links-heavy-diesel-exhaust-lung-cancer
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/kantipur-nepal
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/diesel
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/lung-cancer
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/lung-disease
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health-effects
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/mining
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/pollution
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/china
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/mexico
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/portugal
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/united-states-america-us
[13] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-quality-standards
[14] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution