Chlorpyrifos in the ambient air of houses treated for termites

Chlorpyrifos levels were determined in the air of houses following their treatment for termites by pest control companies. Recorded levels were compared with the proposed NAS guideline level of 10 mg/cu m, indicative of a safe level for residences. Seven of the 16 homes tested had detectable chlorpyrifos in air samples taken in living spaces before application. Pesticide levels detected in post-application air samples were in the 0.10-8.54 mg/cu m range. Air samples from treated houses on sandy soils contained significantly more chlorpyrifos following its application than that from homes on clay soil. None of the samples exceeded the recommended guidelines.