In factories of any kind, the purpose of chimneys is to carry their smoke from the furnaces to the air. Some may wonder why these particular chimneys are so tall. Tall chimneys indeed make for a better draught for the furnaces, but that is not the important thing here. The point is that, with our present way of burning coal, a large amount of the coal is wasted and simply blown up the chimney without being burnt in the form of smoke. When this coal-laden smoke reaches the atmosphere, it can harm anything that comes into contact with it humans, animals, plants, houses, etc.
However, the higher this smoke is sent into the air, the better its chance of being blown away and thinning out before settling. Evidently, it would not do to have a chimney discharging factory smoke at the level of somebody’s bedroom window, for instance.
Tall chimneys are essential for yet another reason. Even when the fuel is burnt in the factories in a proper way, carbonic acid gas is always produced after all, the chief element in fuel is carbon. This gas is a poison to us if there is too much of it in the air, and so it must be sent into the air as far away from our mouths as possible.
Factory smoke is a major contributor to the problem of air pollution, which is something that we need to combat as much as possible.