Acid rain Acid rain Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals and infrastructure. Acid rain is caused by emissions of sulphur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. Some governments have made efforts since the 1970s to reduce the release of sulphur dioxide and nitrogen oxide into the atmosphere with positive results. Nitrogen oxides can also be produced naturally by lightning strikes, and sulphur dioxide
Ontario electricity policy of carbon dioxide, 0.05 kg of sulfur dioxide and 0.8 kg of nitrogen oxides (NO) per megawatt-hour of energy generated. Compared with coal, natural gas generates about half as much carbon dioxide, one-third of the nitrogen oxides, and one one-hundredth of the sulfur oxides. Natural gas is most commonly used for heating applications in homes and businesses but natural gas-fired power generation is also a significant component of the power supply mix, accounting for 8% of Ontario's power generation capacity, with 102 natural gas generating stations. This capacity is set to increase from 5,103 MW to 9,300 MW by 2010.