Wɔbɔɔ Michael Hart, a ofi San Diego, sobo sɛ wabu mmara a U.S. aban ahyɛ a wɔde rebɔ ogya a ɛma ewim yɛ hye no so. Ɛyɛ mmara sɛ wɔde hydrofluorocarbons (HFCs) bɛba ɔman no mu bere a wonni tumi krataa soronko a Environmental Protection Agency (EPA) de ama no. Wɔbɔ Hart sobo sɛ ɔtɔɔ nnuhwam wɔ Mexico na ɔde kɔtoo U.S. mu denam de a ɔde siee ntamasin ne nnwinnade so.