What is Headspace (gas)? Package or "Headspace" gases are the gases primarily used in the process of controlled atmosphere (CA) storage or modified atmosphere packaging (MAP) for produce. Gases commonly used for packaging are oxygen (O2), carbon dioxide (CO2), nitrogen (N2), and occasionally argon, helium, sulfur dioxide, or carbon monoxide. The atmospheres in both CA and MAP consist of mixtures of the benign atmospheric gases O2, CO2, and N2 with the occasional addition of other gases. The key to this approach lies in selecting the correct proportions of gases. The technologies thus rely on gases that are safe, common, cheap, readily available, and not considered chemical additives. Different combinations of these gases are appropriate for different fruits and vegetables. The proper marriage of product, gas mixture, and package type has been the subject of most of the development efforts in the area.