Acid rain refers to a combination of pollutants that leads to the formation of acidic waters that dissolve into the soil, forming mineral deposits and depleting soil fertility. It is caused by air pollution from industrial activity such as burning fossil fuels and chemical discharges from factories.
While much of the acid rain in Europe was due to atmospheric deposition (the release of chemicals into the atmosphere), this is increasingly being cleaned up through new regulations on industrial emissions.
Acid rain, however, remains a problem in other regions of the globe, especially in Asia, where the majority of pollution is still primarily due to atmospheric deposition