Broccoli tissue, ranging in weight from 7 to 21 g, was sealed in packages made from low-density polyethylene (LDPE) of various thickness and permeability to establish a range of O2 levels in the package headspace. A pouch containing either hydrogen peroxide (H2O2) or water as a control was also sealed in the package. For packages that developed anaerobic atmospheres, inclusion of H2O2 permitted the maintenance of aerobic conditions for up to 3 days at ambient room temperature. These results suggest that the plant tissue is able to actively metabolize the H2O2 vapor to generate O2, which will prevent the development of low-O2 conditions in packaged produce, even under conditions of elevated storage temperature.