What is the appropriate exposure frequency for a typical commercial/industrial worker — 250 days, 219 days, or some other derived value for intermittent exposure?
The model default value for exposure frequency (EF) is 219 days/year. This value is a central tendency estimate for non-residential exposure scenarios (i.e., both commercial and industrial), and corresponds to the average time spent at work by both full- and part-time workers engaged in non-contact-intensive activities. If workers are engaged in full-time activities, then an EF greater than 219 days/year may be appropriate. The adult lead methodology is designed to estimate blood lead concentrations (PbB) for workers who have a sustained period of contact with exposure media. The default assumption for the averaging time (AT) is one year (365 days), which is sufficient time for PbB to approach quasi-steady state (see Recommendations of the Technical Review Workgroup for Lead for an Approach to Assessing Risks Associated with Adult Exposures to Lead in Soil, December 1996). If exposures are expected to occur over a shorter time interval, then EF should not be prorated over the entire ye
