As part of the hazard assessment under 40 CFR Part 68, Subpart B, a source is required to estimate in its risk management plan (RMP) the population within a circle that has its center at the process and its radius equal to the distance to the endpoint concentration (40 CFR §68.30). If the estimated population changes, would the RMP have to be updated?
No. Changes in U.S. Census data do not necessitate the revision of the RMP. However, all updates to the RMP should utilize the most recent U.S. Census data.