In laboratory testing EPDM is subject to the most severe heat aging where samples are subjected to temperatures of 240 F for 4 weeks. Also, in several studies field samples were collected from various geographic locations after years of exposure and in both cases (laboratory and field), the physical properties of the samples exceeded the original ASTM specification. Presently, there are numerous EPDM installations throughout colder regions in the U. S. (i. e. , Alaska, Minnesota) as well as in the hot and humid climates of southern Florida and Texas. For the past 25 years, EPDM has been the roofing membrane of choice for many commercial and manufacturing facilities internationally. The material will not shatter in extreme, cold temperatures and remains flexible under severe thermal shock such as in dessert areas where evenings are extremely cold and days extremely hot.