Unit 1: Negative externalities from diesel use

Pretty bad, according to the BBC

http://www.bbc.co.uk/news/health-18420990#

but maybe there's hope for the future, according to Aljazeera (in this tutor2u post)

http://www.tutor2u.net/blog/index.php/economics/comments/unit-1-miro-greener-fuels-for-improved-public-health