Comparison of two floor mat lead dust collection methods and their application in pre-1950 and new urban houses

This study investigated commercial floor mats as an alternative method to assess lead in residential dust in inner-city houses. Mats were placed for 3 weeks in interior entryways of 34 row houses built before 1950 and 17 new row houses in Baltimore City. A high volume sampler (an HVS3 floor model cyclone-based vacuum) and a hand-held portable cyclone sampler were used in the laboratory to collect side-by-side samples of mat dust. Both devices yielded comparable estimates of lead dust deposition, dust lead concentration, and dust deposition on field mat samples and had similar sampling efficiencies on mats spiked with various types of standard reference materials. The older houses had significantly higher daily lead dust deposition (GM = 130 μg/ft²/day by HVS3) than the newer houses (GM = 9 μg/ft²/day by HVS3), due to higher dust lead concentrations (GM = 1149 ppm vs GM = 107 ppm by HVS3) and not to differences in daily dust deposition (GM = 118 mg/ft²/day vs GM = 87 mg/ft²/day by HVS3). Mats were found to be a feasible method for the collection of dust that has accumulated for a known amount of time. Current wipe and vacuum methods do not allow for the estimation of dust deposition rates. Further research is needed to understand the role of floor mats as a risk assessment tool.