Although ripening of tomatoes can be retarded by low temperatures, storage under refrigeration can cause chilling injury and increase of fungal contamination. Use of atmospherics rich in CO2 and low O2 can also slow down the ripening process of tomatoes. What exposure time is necessary for the concentration of CO2 at the center of a spherical tomato of 8 cm diameter to change to 15% by volume of air inside the tomato? The initial concentration of CO2 in air in the tomato is 2% by volume. The storage room and the surface of tomato are maintained at 18% by volume of CO2. The effective diffusivity of CO2 in the tomato was found to be 2.3 x 10-8 m2/s.