Selecting a Lead Hazard Control Strategy Based on Dust Lead Loading and Housing Condition: II. Application of Housing Assessment Tool (HAT) Modeling Results

Abstract

In Part I in this issue, modeling was used to identify a Housing Assessment Tool (HAT) that can be used to predict relative intervention effectiveness for a range of intervention intensities and baseline dust lead loadings in occupied dwellings. The HAT predicts one year post-intervention floor and windowsill loadings and the probability that these loadings will exceed current federal lead hazard standards. This article illustrates the field application of the HAT, helping practitioners determine the minimum intervention intensity needed to reach “acceptable” one year post-intervention levels, with acceptability defined based on specific project needs, local needs, regulations, and resource constraints. The HAT is used to classify a dwelling's baseline condition as good or poor. If the average number of interior non-intact painted surfaces per room is ≥2, then the dwelling is rated as poor. If exterior windows/doors are deteriorated and the average number of exterior non-intact painted surfaces per building side is ≥5, then the dwelling is rated as poor. If neither of these conditions is true, then the dwelling's HAT rating is good. The HAT rating is then combined with baseline average floor loading to help select the treatment intensity. For example, if the baseline floor loading is 100 μg/ft2 (1,075 μg/m2 and the HAT rating is poor, the probability that the one-year floor loading exceeds the federal standard of 40 μg/ft2 (430 μg/m2 is 27% for a high-intensity strategy (i.e., window lead abatement with other treatments) but is 54% for a lower-intensity strategy (i.e., cleaning and spot painting). If the HAT rating is good, the probability that the one-year floor loading exceeds 40 μg/ft2 is approximately the same for low-and high-intensity strategies (18% for window lead abatement with other treatments compared with 16% for cleaning and spot painting). Lead hazard control practitioners can use this information to make empirically based judgments about the treatment intensity needed to ensure that one year post-intervention loadings remain below federal standards.