Persistence of pesticides in residential indoor air and chair seat foam

Pesticides were measured in the indoor air and chair seat foam of two homes which had known minimal pesticide use over a six-year period. Despite active measures taken to reduce their levels, the indoor air concentrations of chlorpyrifos and diazinon persisted for years in both homes. Crude estimates of the dissipation half-life were about 5 years for chlorpyrifos and more than 2 years for diazinon. Many pesticides partially migrated from the indoor air into the cushion foam, through repeated decompressions from sitting in the chair, but did not completely penetrate to establish equilibrium; nearly half of the concentration gradients persisted for four years. More volatile chemicals, such as diazinon and ortho-phenylphenol, did sometimes equilibrate. Concentration gradients into seat cushion foam with a known usage history can provide insight into the past exposure of residents to the detected pesticides.