ATF investigation at West, Texas, focused on criminal possibilities rather than inherent instability of the explosive fertilizer.
2014 IFW article outlined the many unknowns related this common yet dangerous fertilizer.
Blast at fertilizer storage facility killed 15 people and caused hundreds of injuries.
Three years and nine months after an April 2013 ammonium nitrate explosion at a fertilizer plant in West, Texas, killed 15 people, all but three of them emergency responders, the U.S. Environmental Protection Agency put new rules in place to prevent a disaster like it from ever happening again.
Events at West focus on plant's 'seed room'