What Set It Off

A factory made chewing gum. Workers dusted the gum with a fine powder by hand, and a machine sprayed it with liquid nitrogen. The powder dust built up and hung in the air. Months earlier an insurance inspector had warned the company the dust was an explosion hazard and recommended an exhaust system. One night the plant exploded. Six workers died and more than fifty were hurt. Experts could not agree on what triggered the blast: a mechanical spark, or liquid nitrogen turning oxygen to liquid. The company and four managers were charged with manslaughter.