Case Study of Organochlorine Pesticides in the Indoor Air of a Home

The indoor air concentrations of aldrin and dieldrin, two organochlorine termiticides, were monitored in the basement, main level, and upstairs area of a treated home. Aldrin and dieldrin concentrations were measured in the home between September 1987 and April 1995. Aldrin and dieldrin concentrations were highest in the basement, where the aldrin and dieldrin had been applied. Aldrin concentrations decreased with a half-life of 16 months in both the main level and basement of the home, but dieldrin concentrations remained the same over the study period. In 1995, we expanded our measurements to include the indoor and outdoor air concentrations of a set of organochlorine compounds used as pesticides. These compounds include aldrin, dieldrin, four chlordanes, pentachloroanisole, and the hexachlorocyclo- hexanes. All compounds except the hexachlorocyclohexanes had higher indoor than outdoor air concentrations, implying that their sources were in the home. In the indoor air, aldrin, dieldrin, and the chlordanes had higher concentrations in the basement than on the main level, indicating a basement source. Pentachloroanisole was evenly distributed throughout the indoor air, implying that it does not originate in the basement. Two remediation attempts were made to stop aldrin and dieldrin from infiltrating into the home. First, the basement walls were covered with tar and plastic to form a barrier against the foundation. Second, the basement air pressure was manipulated. While the tar and plastic appear to have had little effect, creating a positive indoor air pressure lowered the air concentrations of the two pesticides.