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.

Keywords:

• dust lead loading
• housing condition
• intervention strategy
• lead hazard control
• risk assessment

Notes

^AHAT rating = poor if the average number of non-intact interior paint components exceeds two or if exterior window/doors are deteriorated and there were five or more exterior components with non-intact paint. Otherwise, the HAT rating = good.

^B Italicized strategy numbers shown in parentheses indicate strategies that yielded predicted one-year loadings that were significantly different from that of the strategy heading for that column.

^CThe effect of having no exterior work done is shown only for HAT rating = good because exterior work did not have a significant effect on predicted one-year floor dust loadings when HAT rating = poor.

^DSite/soil work did not have a significant effect on predicted one-year sill dust lead loadings.

^A40 μg/ft² for floors; 250 μg/ft² sills.

^BWhen exterior work but no site/soil work is done.

*Deceased