A comparison of the lead particle content of indoor dust before and after a lead paint abatement: A new source of lead recontamination

The lead particle content of floor dust in a housing unit scheduled for interior lead paint hazard removal was characterised microscopically to identify the contributing source(s) of the lead. It was hypothesised that elevated levels of lead in the dust resulted from the deterioration of the lead-based paint on the indoor surfaces. The question of lead particle source attribution was addressed using a combination of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). SEM/EDS provided data on the size, shape, and composition of the individual lead-containing dust particles. The floor dusts which were analysed contained a variety of lead particle types and eight of these types from several rooms exhibited unique morphological and/or chemical characteristics. These were variously classified as lead paint particles. The lead levels in the floor dusts prior to the abatement were ≥ 100 μg·ft^-2. The floor dust lead concentrations immediately following the abatement were all less than the pre-abatement levels, but a re-sampling 2 months after the abatement found that the amount of lead in two of the rooms was approximately 3 and 4.5 times higher than the levels prior to the abatement. SEM/EDS analysis of the floor dusts samples collected 2 months after the abatement showed that in these two rooms the constituent particulate lead differed from that in any of the pre-abatement dusts. Following attempts to identify possible sources of recontamination, it was found that this previously unidentified particulate lead was consistent in form with lead scraped from the interior of one of the radiators which had been removed from the complex some time after the abatement. Residual water spilling from the radiators during the course of removal was, in all likelihood, the cause of the unexpectedly elevated dust lead levels.