Here's a clue

EPA measurements of benzene in urban areas ranges from 0.02 parts per billion to 112 parts per billion.  That is parts per billion, not parts per million. 3500 parts per million is the highest level ever recorded in large open air areas.  Now, with winds coming mostly out of southerly directions, do you really think that gulf coast auto exhaust and cigarettes led to such an astronomical measurement?

So, let's see, what else might have happened to cause such high levels of benzene and other toxic compounds in the air in the gulf area? What else was there that hadn't been before? Why, I do believe it is all that oil and dispersant.

Come on, buddy - you aren't just disputing wild theories here.

BTW, benzene is carcinogenic at mere parts per billion.  What do you suppose high parts per million might do?

http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s019benz.pdf