For the two chemicals that did not have established CRELs, propylene glycol and nicotine, we
used 1% of the California OSHA [6] occupational 8-hour Permissible Exposure Guideline, with
the exception of lead, for which we used the Environmental Protection Agency [7] National Air
Quality Standards (NAAQS), 3-month average requirement. We note that the use of 1% of the
occupational guideline for a non-occupational guideline (i.e. OEHHA CRELs) reflects the need
to account for longer than 40 hr/week exposures and the presence of sensitive individuals. For
the 13 chemicals that have both a non-occupational CREL and an occupational 8-hour PEL (Cal/OSHA), the non-occupational CRELs average 1 percent of the occupational 8-hour
exposure guidelines (range 0.02-3.9 %).