Dry ice is widely used as a refrigerant for preservation of perishable commodities transported by air (e.g., food products, biomedical supplies, biological samples, and even some industrial products such as adhesives). Dry ice sublimation producing excess CO2 gas may be dangerous in confined spaces where there is an absence of ventilation or ventilation rates are low. According to the Federal Aviation Administration (FAA), the transportation of dry ice on aircraft should be limited by the ventilation capacity of the aircraft itself so that the concentration of carbon dioxide in the aircraft cabin does not exceed 0.5%. The air carrier industry has experienced difficulty calculating dry ice capacity on aircraft for a number of reasons. FAA has calculated the sublimation rate for dry ice as 2% per hour; however, there are questions about this rate. Factors that influence sublimation include the form of the dry ice itself (e.g., block, pellet, or snow), the nature and quality of the packaging and insulation, and the initial temperature of the contents. Also, the ventilation rate of aircraft varies by aircraft type. For example, new aircraft engines or retrofitted air conditioning systems may influence dry ice sublimation. The number of air conditioning packs operated during flight also influences the rate of ventilation. Finally, the configuration of the aircraft influences the quality of cabin air. For example, passenger aircraft and cargo-only aircraft vary widely in the dry ice loads they can carry. In addition, some older generation aircraft have no ventilation between the cargo and passenger decks, while newer generation aircraft recirculate air through the cargo deck compartments. Research is needed to clarifiy how to use dry ice as a refrigerant so as to enable the safe transport of goods on aircraft.
The objective of this research is to develop a decision tool(s) to assist passenger and cargo-only aircraft operators in determining the maximum quantity of dry ice that can be safely carried as cargo.