Investigators have linked a number of fires to radiant heaters used by exterminators. Last year a 50-unit condominium in Edmonton burned when exterminators used propane fired heaters to bring the temperature in the infested room above 120 degrees. Exterminators say more than an hour and a half of exposure to such high temperatures ensures a 100 percent bed bug kill but fire experts warn heating confined spaces with powerful heaters creates a serious fire hazard.