How do sulfur dioxide and nitrogen oxides cause acid rain?

Sulfur dioxide ($S{O}_2$) and nitrogen oxides ($N{O}_x$) are the primary pollutants responsible for acid rain. These gases are released into the atmosphere largely through the combustion of fossil fuels in power plants, industrial facilities, and vehicles.12

Once these pollutants reach the atmosphere, they undergo chemical reactions with water, oxygen, and other chemicals. These processes transform sulfur dioxide into sulfuric acid ($H_{2}S{O}_4$) and nitrogen oxides into nitric acid ($HN{O}_3$).1

These acids subsequently mix with cloud moisture, which significantly lowers the pH of precipitation. When this moisture falls to the ground as rain, snow, or fog, it is classified as acid rain. Because these pollutants can travel long distances, they often affect regions far from their original emission sources. To mitigate these environmental impacts, industries often employ flue gas treatment technologies, such as scrubbers and denitrification units, to remove these harmful gases before they are released.123