MD 760 - Effectiveness of Maryland's Lead Law

Project Funders: U.S. Department of Housing and Urban Development (HUD) and the Abell Foundation

Project Partners: Baltimore City Health Department

Project Contact: Jill Breysse,, 443.539.4155

Project Description: In 1994, Maryland enacted a law that prescribes a lead-based paint risk reduction standard for pre-1950, privately-owned rental housing. This standard applies at each tenancy change and requires sampling to verify that dust lead loadings are within acceptable limits or performing specific lead hazard reduction treatments, followed by an independent visual inspection without dust sampling. In this project, NCHH evaluated the ability of visual inspection alone to predict treatment completion and dust lead loadings.

NCHH enrolled 52 Baltimore housing units into the study and performed the law-specified treatments. Before treatment, study risk assessors conducted visual assessments and dust lead wipe sampling in each unit. After treatment, Maryland-certified visual inspectors conducted the law’s required visual inspection, followed by the study risk assessors, who performed a separate visual assessment and collected dust wipe samples. One year later, study risk assessors performed another visual assessment and dust wipe sampling (n=34).

We found that dust lead loadings declined significantly immediately after prescribed lead treatments were implemented. Fifty-three percent, 20%, and 47% of units had at least one sample that exceeded 1995 EPA/HUD floor, window sill, and window trough clearance guidance of 100, 500, and 800 μg/ft², respectively. Overall, 73% of units had one or more immediate post-intervention single surface sample results exceeding the 1995 clearance values that were in effect at the time of the study. One-year post-intervention loadings remained significantly below pre-intervention levels for floors but not window sills or troughs.

The conclusion of this project is that, without dust lead testing, visual assessments alone do not ensure that prescribed treatments were completed or that dust lead loadings were below clearance values.

Project Resources

Immediate and One-Year Post-Intervention Effectiveness of Maryland’s Lead Law Treatments [PDF]