Abstract: Refrigerated containers that contain continuously circulating air or oxygen-containing gas into which ozone is injected to preserve perishable food products that are susceptible to spoilage when stored for extended periods of time are disclosed. The ozone content of the circulating air is continuously monitored by an ozone sensor and adjustments to the amount and rate of ozone injection are continuously made by a controller on the basis of signals from the ozone sensor and other sensors.