Concentration of soil fumigants in the soil atmosphere at the Florida sites at 2 and 5 d after application. Air samples were collected at a 12-cm depth in the center of the bed. 1,3-Dichloropropene (1,3-D) was not applied to Site 3. Sites 1 and 3 were covered by metalized film; Site 2 was covered by virtually impermeable film. MITC, methyl isothiocyanate; Pic, chloropicrin.