In London in 1952, more than 4,000 people suddenly died as a result of breathing difficulties brought on by factories burning coal and oil producing sulfur dioxide which invaded the lung cells and reduced the ability of the lung vesicles to deal with dust.
一九五二年英國倫敦曾在五天之內，因為工廠焚燒煤、油產生的二氧化硫，侵襲人體肺部氣管細胞，降低肺泡對塵埃等污染物的作用，導致四千多人呼吸困難而死亡。