Chlorpyrifos in the air and soil of houses four years after its application for termite control

Chlorpyrifos levels were determined in indoor ambient air samples and in adjacent soil samples from residences 4 yr after termiticide application. Levels of the chemical in rooms were in the 1-9 mu g/m super(3) range, and much more chlorpyrifos was present in the air of houses built over sand than clay soils. Chlorpyrifos detected in the soil adjacent to the exterior and interior foundation walls for all houses was in the 0-1640 and 0-1684 ppm ranges, respectively.