That's because such gases contribute to the greenhouse effect, which has been linked to global warming. However, EPA agreed to allow use of carbon dioxide as an alternative to the banned gases. (Although carbon dioxide is also a greenhouse gas, its global warming potential in this case is said to be mitigated by the fact manufacturers will use carbon dioxide already present in the atmosphere or already produced as a by-product of existing industrial processes.)
The Environmental Protection Agency (EPA) has proposed a ban on two hydrofluorocarbon gases, including HF3-134a, used as refrigerants in self-chilling beverage cans.
May 31, 1998