Aerosolization during indoor lead abatement: Characterization of released particles and evaluation of lead hazard control procedures

Lead is a toxic substance and a ubiquitous environmental contaminant. Many studies have shown its negative health effects on psychological development, neuromotor system and many other body organs. Lead was added to paint in the form of white lead to reinforce the paint and produce a tough and flexible film. It is estimated that more than 3 million tons of lead have been used in the form of lead-based paint in the U.S. during the past 100 years. As a result, about 38 million homes still contain leaded paint. For this reason, hundreds of millions of dollars have been spent in the U.S. for lead hazard control. The leaded particles aerosolized during lead hazard reduction work are a health hazard for the workers. Significant levels of leaded particles representing health hazards are aerosolized during lead abatement. Few studies regarding these aerosols have been performed.; The two main goals of the research described in this dissertation were (1) to characterize the airborne leaded particles and (2) to apply the acquired knowledge to the evaluation of various lead hazard control procedures.; The first goal was to investigate the fundamental characteristics of the particles aerosolized during lead abatement. An Environmental Test Chamber was designed and constructed in the Kettering building at the University of Cincinnati. Wood doors coated with lead-based paint were abated in the chamber by dry scraping, wet scraping, or dry machine sanding. The airborne particle concentration was measured with the Grimm particle size spectrometer. The size distribution of the airborne particles changed substantially with time. The airborne particle concentration for each specific size was found to decay exponentially in calm air condition. Size selective air sampling on filters and subsequent laboratory lead analysis of them showed no significant effect of particle size on the percent lead.; The second goal was achieved by the following three studies. The first study was to investigate the relationship between the surface lead level on the substrate and the percent lead in the particles aerosolized during lead abatement. A significant relationship for dry scraping was found, but not for wet scraping and dry machine sanding. This was attributed to the difference in water absorption properties of the paint layers and different particle aerosolization mechanisms of each paint removal method. The second study has demonstrated that there was no need to extend either the first or the second waiting period beyond the currently recommended one-hour interval. The third study evaluated the final cleaning after lead abatement. The change in airborne lead concentration and the potential floor lead loading after each cleaning procedure was determined. Considerable resuspension of leaded particles was detected during dry sweeping. The first HEPA vacuuming significantly decreased the airborne lead mass. Wet mopping was effective in reducing the lead loading significantly below the clearance level. The second HEPA vacuuming resulted in further reduction of the airborne lead mass concentration. The current cleaning procedure was found to be sufficient in reducing the floor lead loading below the HUD clearance standard of 40 μg/ft2. Several modifications were proposed to further improve the cleaning effectiveness.