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What causes acid rain from coal combustion?

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coal utilization Cross-regenerative coke oven. (A) Cross section, showing the alternating arrangement of flue walls and ovens; (B) longitudinal section, showing (left) a series of combustion flues in a single flue wall and (right) part of a long, slotlike oven.

Acid rain resulting from coal combustion is primarily caused by the release of sulfur dioxide ( $S O_{2}$ ) and nitrogen oxides ( $N O_{x}$ ) into the atmosphere.12

When coal is burned, the sulfur and nitrogen contained within it react with oxygen to form these gaseous oxides. Once emitted, these gases undergo chemical reactions in the atmosphere with water, oxygen, and other chemicals to produce sulfuric acid ( $H_{2} S O_{4}$ ) and nitric acid ( $H N O_{3}$ ). These acids then mix with cloud moisture and fall to the Earth's surface as acid rain, which lowers the pH of precipitation and can cause significant environmental damage to forests, aquatic ecosystems, and human-made materials.3415

Because acid rain poses a serious threat to environmental health and biodiversity, it is an ethical imperative to prioritize the development and implementation of cleaner energy technologies and emission-control systems, such as scrubbers or fluidized-bed combustion, to mitigate these harmful pollutants.26