Setting fumigant application buffer zones

California's Department of Pesticide Regulation (DPR) has found unacceptable risk to human health associated with some fumigant inhalation exposure. DPR uses air monitoring data and computer modeling to estimate exposures. Monitoring provides a snapshot of air concentrations in the vicinity of specific pesticide applications. The Industrial Source Complex-Short Term (ISCST) model, a Guassian Plume air dispersion model, estimates air concentrations under a variety of conditions. If monitoring data and computer modeling indicate unacceptable air concentrations in the vicinity of pesticide applications, DPR uses the ISCST model to determine the appropriate size and duration of buffer zones. These techniques are illustrated using methyl bromide as an example.