There are a number of carcinogens present in petroleum compounds. Allowable air concentrations for workers are published by OSHA. Some of the standards are time weighted averages. NIOSH provides guidelines that may be more conservative than OSHA in some cases. There are extensive references on the subject of air quality in oil spills and health and safety considerations at the following CDC site:
http://www.cdc.gov/niosh/topics/oilspillresponse/
For a proper cleanup, there should be a Health and Safety Plan in which potential contaminants, concentrations, exposure pathways, PPE (Personal Protective Equipment) and a good deal more are presented. This information should be provided to the workers along with PPE, training, oversight, etc.. In the instance of air emissions from petroleum, special respirator cartridges (activated carbon) or even SCBA may be indicated IF air concentrations are high enough.
The EPA has been doing limited air testing in LA reported at:
http://www.epa.gov/bpspill/air.html#vocs
They have reported fairly nominal air test results to date. Having no violations however doesn't necessarily mean you can't smell it.
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