Abstract: On May 7, 2011, Employee #1 a coowner of G & W Debris Removal, and three other coworkers were removing mechanical equipment and scrap material from a vacant telecommunications building. Employees #1 and #2 entered through the front glass doors of the building onto the first floor and walked down the steps to the lower level or basement to open the rear doors for two coworkers, but they were apparently overcome by escape of Freon refrigerant gas from four large chiller cooling units in the basement. Employee #1 collapsed face down, unconsciousness, onto the floor. Employee #2 managed to escape from the building and summon help from the other two coworkers. The three men reentered the basement and attempted to rescue employee #1, but they failed. Employee #2 suddenly collapsed and lost consciousness near Employee #1. The other two workers exited the building and called 911. Employees #1 and #2 were pulled from the building by firefighters. Responding emergency crews rushed all four employees to Paoli Memorial Hospital, where Employee #1 was pronounced dead; Employee #2 was hospitalized for two nights in ICU and recovered; and the remaining two employees were hospitalized for one night for further medical evaluation of their symptoms and were released from the hospital.