ror./week (Harvard) as mr./week (HASL)} Fig. 2. Harvard population exposure estimates as a function of comparable Health and Safety Laboratory (HASL) estimates for the eight New England areas examined In any event, there is little doubt that the dosimeter results are too high. This can be shown by carrying out a simple mathematical analysis of the various contributions to the population exposure-level, P, utilizing the accurate Health and Safety Laboratory measurements of outdoor environmental radiation dose rates. If I., In and Iy are the measured mean outdoor dose-rate contributions from cosmic, natural ;-, and fall-out y-radiation, respectively, and J; is the mean indoor y-dose rate pro uced by sources in the building materials, we can write the following expression for P: P=fi(le + 8ly + Snln + In) + fo (Ze + Te + In) where f; and f, are occupancy time factors for indoor and outdoor locations, respectively, and s, and s, are mean transmission factors of the buildings and residences for outdoor fall-out and natural y-radiation. Substituting 8 10