What is the worst known case of air pollution?

Things that cause air pollution: cigarette smoking, some public transport (cars, buses etc...) The effect of air pollution is that it could end our world, there are several ways of stopping air pollution. Inhaling petrol or diesel fumes could damage your lungs and possibly kill you because of the chemicals are poisonous to humans and other kinds of life on earth.

Transportation is a contributor to the worst cases of air pollution in the form of heavy smog. Along with weather conditions, many of the factors above contribute to the smog in major cities. London's Great Smog of 1952 was one of the worst examples. On that year, starting on December 5th, the city was covered with smog for 4 days. Together, excessive use of coal, high atmospheric pressure, light winds and freezing temperatures all caused smog to settle over London. That contributed to many deaths due to respiratory failure. The death toll was estimated around 4000. People couldn't breathe nor see because the smog even entered buildings.

A good second place contender is natural incidents. In 1986, around 1700 were killed by a blanket of CO2 gas which came from around a volcano. Most died in their sleep. There are many ways volcanoes can kill, and this was somewhat unique. Lake Nyos, at 690 feet deep, was heavy enough to keep a lot of CO2 dissolved in it. So the chimney effect of the surrounding volcano caused the gas to concentrate the way it did.