RESUMEN
We examined changes in ambient dust lead (Pb) levels associated with the demolition of older row houses containing lead paint in Baltimore, MD, USA. Our previous paper describes the three study sites, the demolition processes, and increases in the Pb dustfall rate during demolition (>40-fold) and debris removal (>6-fold) within 10 m of sites where wetting was of limited effectiveness. This paper presents the analysis of settled dust collected using a cyclone device from streets, sidewalks, and alleys within 100 m of study sites before, immediately after, and 1 month after demolition. We found acute increases in Pb loadings and dust loadings after demolition and debris removal that are of public health concern. Streets and alleys had the greatest increases in Pb loadings and the highest levels overall. At one site, geometric mean (GM) Pb loadings immediately after demolition increased 200% for streets to 8080 microg/ft(2), 138% for alleys to 6020 microg/ft(2), and 26% for sidewalks to 2170 microg/ft(2). One month after demolition, the GM Pb loadings for streets, alleys, and sidewalks were reduced on average by 41-67% from post-demolition levels and were below baseline levels for alleys and sidewalks. The other main site had smaller increases in GM Pb loadings immediately after demolition-18% for alleys to 1740 microg/ft(2) and 18% for sidewalks to 2050 microg/ft(2)-and a decrease of 29% for streets to 2730 microg/ft(2). Exterior dust is a public health concern because it is a pathway of ambient Pb exposure and a potential source of residential exposure via tracking and re-aerosolization and re-deposition. Our findings highlight the need to control demolition-related Pb deposition and to educate planners, contractors, and health and housing agencies. This is particularly important given the large numbers of aging US dwellings that will be razed as part of future urban redevelopment efforts.