As a first approximation, workers can often legally be exposed to 1,000 times greater concentrations of carcinogenic air pollutants than those permitted under federal environmental regulations. Even for the very few carcinogens regulated by OSHA, this agency has generally construed a lifetime risk of 10^-3 to be an acceptable stopping point for regulation, whereas EPA has often pursued 10^-6 as a desired stopping point. An analysis of the prevailing exposure levels in workplaces and the ambient environment will gauge, for a representative subset of substances, to what extent this thousand-fold first approximation is an under- or over-estimate of the disparity.  Results of this analysis will also shed light on the adequacy of OSHA's enforcement of its existing health standards, and of the extent to which OSHA properly views patterns of worker over-exposures as “wake-up calls” to increase inspections and exposure monitoring.  More specifically, extending this analysis by linking it to environmental enforcement information will provide a preliminary test of an intriguing hypothesis supported thus far by some anecdotal information—that interventions to reduce air emissions to the ambient environment can sometimes have the perverse effect of further increasing occupational exposures inside the facilities where the “improvements” are made.