The combustion of the fossil fuel from the exhaust gas of a car, a factory, and a thermal power plant of acid rain is the cause. SOx or NOx is contained in the gas which burned. They cause a chemical change in the atmosphere, become sulfuric acid and nitric acid, and are taken in by rain, snow, fog, etc. in the atmosphere. And the thing of the phenomenon in which it becomes pH 5.6 or less acidity, and comes down on the ground is said