Which is safer-staying at home, traveling to work on public transport, or working in the office? Surprisingly, each of these carries the same risk, which is very low. However, what about flying compared to working in the chemical industry? Unfortunately, the former is 65 times riskier than the latter! In fact, the accident rate of workers in the chemical industry is less than that of almost any of human activity, and almost as safe as staying at home. The trouble with the chemical industry is that when things go wrong they often cause death to those living nearby. It is this which makes chemical accidents so newsworthy. Fortunately, they are extremely rare. The most famous ones happened at Texas City (1947), Flixborough (1974), Seveso (1976), Pemex (1984) and Bhopal (1984). Some of these are always in the minds of the people even though the loss of life was small. No one died at Seveso, and only 28 workers at Flixborough. The worst accident of all was Bhopal, where up to 3,000 were killed. The Texas City explosion of fertilizer killed 552. The Pemex fire at a storage plant for natural gas in the suburbs of Mexico City took 542 lives, just a month before the unfortunate event at Bhopal. Some experts have discussed these accidents and used each accident to illustrate a particular danger. Thus the Texas City explosion was caused by tons of ammonium nitrate (硝酸铵) ,which is safe unless stored in great quantity. The Flixborough fireball was the fault of management, which took risks to keep production going during essential repairs. The Seveso accident shows what happens if the local authorities lack knowledge of the danger on their doorstep. When the poisonous gas drifted over the town, local leaders were incapable of taking effective action. The Pemex fire was made worse by an overloaded site in an overcrowded suburb. The fire set off a chain reaction exploding storage tanks. Yet, by a miracle, the two largest tanks did not explode. Had these caught fire, then 3,000 strong rescue team and fire fighters would all have died.