After three decades of epidemiological research, diesel exhaust was classified as a carcinogen in humans by the International Agency for Research on Cancer (IARC) in 2012 based on evidence of its carcinogenicity to the lung.1 This determination was largely based on results from two recent epidemiological studies of occupational diesel exhaust exposures among non-metal miners (Diesel Exhaust in Miners Study (DEMS))2 ,3 and truck drivers.4 The next challenge is to determine how to regulate exposure to diesel exhaust. Governmental regulatory agencies are charged with setting safe levels of exposure in the workplace and in the outdoor ambient environment in various countries. Much of the current regulatory activity has been focused on the workplace. Many countries lack workplace regulations, and many others have regulations that need re-evaluation by quantitative risk assessors in light of the new research findings. The new findings and the potential need for regulation has stimulated exposure assessments such as that led by Peters et al5 in Western Australian mining.

In 2013, the Health Effects Institute (HEI) convened an independent panel of scientists to evaluate whether the findings from the two new studies of non-metal miners and truck drivers were suitable for conducting quantitative risk assessment. In 2015, the HEI panel issued a report indicating that they found the studies to be ‘well designed and well conducted’; …