in response to a confidential request for a health hazard evaluation (HHE), investigators from the National Institute for Occupational Safety and Health (NIOSH) conducted investigations at the Delaware County Resource Recovery Facility (DCRRF), a municipal waste incinerator located in Chester, Pennsylvania. The HHE request was submitted in response to employees' concern regarding exposure to lead, incinerator ash dust, and heat stress. Health complaints reported include ear, nose, and throat problems, eye irritation, and skin rash. The DCRRF burns municipal waste and refuse-derived fuel (RDF) from Delaware County, the City of Philadelphia, and New York City.Analytical results from bulk and wipe samples collected during the initial walkthrough survey in December 1991, confirmed that lead and other metals were present in settled dust throughout the plant. Samples of settled dust from walking and working surfaces were collected along with fly ash and conditioned bottom ash samples from the incinerators. Hand and table wipe samples taken in a contractor's break trailer located on site showed that lead, chromium, cadmium, and nickel were present on lunch tables and on workers' hands. Based upon the initial observations and analytical results, a decision was made to return to the DCRRF. On June 23-24, 1992, full-shift personal air monitoring was conducted to determine exposures to lead and other metals, respirable silica, and respirable dust. Heat stress measurements were also made in certain areas on the fourth, fifth, and sixth floors of the facility.In comparison to other metals, lead was found in the greatest concentration on the bulk, wipe, and air samples taken at the facility. However, personal breathing zone (PBZ) samples taken during the investigation showed that airborne concentrations of lead, which ranged from non-detectable to 4.6 µg/m 3 , were well below the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 50 micrograms per cubic meter of air (µg/m 3 ) as an 8-hour time weighted average (TWA). Personal breathing zone samples for cadmium and chromium ranged from non-detectable to 0.11 µg/m 3 and 0.72 µg/m 3 , respectively. The current OSHA PEL for cadmium (dust) is 5 µg/m 3 . NIOSH recommends exposure to cadmium dusts and fumes be reduced to the lowest feasible concentration, or 10 µg/m 3 , which is a concentration based on analytical limits of detection reported for the method. These concentrations can be subject to change as method sensitivities change and improve. The OSHA PEL for chromium (metal) is 1 mg/m 3 as an 8-hour TWA. NIOSH recommends that Cr(VI) compounds be considered potential carcinogens, the NIOSH REL for these compounds is 1 µg/m 3 for a 10-hour TWA. Nickel was not detected.This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual invo...