Air concentrations of paraquat were measured on summer days by Makovskii (1972) using the method of Calderbank & Yuen (1965). About 1 - 1.3 kg paraquat/ha had been applied as a herbicide or desiccant in 0.25 - 0.35% water solutions. The paraquat aerosol concentrations varied according to spraying method and work-place (Table 5). Using the same analytical method, Staiff et al. (1975) examined 35 sites after paraquat application with tractor-mounted field sprayers or hand-pressure garden dispensers. The working solutions contained 0.15% paraquat for field use, and 0.44% for garden use. The respiratory exposure of field and garden operators was below the limit of detection (