This story (http://www.southernstudies.org/2010/05/air-tests-from-the-louisiana-coas...) notes the EPA's air testing data taken from Venice, Louisiana shows "levels of airborne chemicals have far exceeded state standards and what's considered safe for human exposure." Chemicals discussed include hydrogen sulfide (100 greater than safe levels) and volatile organic chemicals such as benzene and methylene.

Exposure to these chemicals can cause reactions ranging from eye irritation to cancer.