af347763___Inc____SCR___Facts_about_SCR__THE_TRUTH
[COMPETITOR RELEASED MYTHS] MYTH: DEF is a toxic material that degrades in heat and cold. [THE TRUTH] 
FACT: Degradation won’t be a problem with safe, nontoxic DEF. DEF is a benign, noncorrosive, nonhazardous, nontoxic, nonpolluting and nonflammable solution of 32.5 percent urea and deionized water. It’s already widely used in industry and agriculture. DEF does not become toxic at any temperature. SCR has been used in Europe for years, in climates very similar to those in North America, yet degradation has not been an issue. During very low temperatures, if the DEF freezes, the SCR system will quickly thaw the DEF back to its original form. Normal operation will not be disturbed. Like any automotive fluid, DEF will degrade during long periods of disuse. But even taking into consideration the typical period of bus inactivity during summer vacation, degradation won’t be a problem.
Cardinal Bus Sales & Service, Inc. - SCR - Facts about SCR
THE TRUTH