To make life easier, human beings utilized various natural resources. They have made several facilities that use the energy of the earth’s resources. Acid rain is one of the utmost serious problems of the environment that arose due to air pollution. Any kind of precipitation which has acidic nature is called “Acid Rain”. It has a pH of less than 5.6. It occurs when from various sources, emission of Sulphur dioxide & Nitrogen oxide take place then these pollutants mix with the Oxygen, Carbon & other chemicals & form acidic compounds like Sulphuric acid & Nitric acid in the atmosphere which precipitate in the form of snow, fog or rain. For industries & power plants, the uses of tall smokestacks have increased the production of atmospheric pollutants which are transported locally & worldwide & spreading acid rain It is recognized as one of the famous environmental problems in East Asia, North American, & Europe.


“Acid Rain” is one of the utmost serious environment problems that arose due to air pollution. It also contributes to climate warming. It has a pH of less than 5.6 . The main purpose of the review is to emphasize the causes of it, its various effects, and different ways to control acid rain. 

The primary cause of acid rain is the emission of Sulphur dioxide and Nitrogen oxide. These environment pollutants come from various activates of human such as the combustion of fossil fuels, burnable waste in automobiles, and   thermal power plants. These chemicals become acidic after mixing with the rainwater and precipitate in the form of rain, fog & snow & exert various effects on the ecosystem, forests, plant, soil, buildings, monuments& water bodies as well as on human health. 

History of Acid Rain:

In the mid-19th century, it was firstly observed in Europe. Then, In 1845, Ducros was the first scientist who recognized acid rain. Afterward, In 1853, acidic rain was founded. In 1852, the term “Acid rain” was developed by an English chemist Robert Angus Smith who noticed leaves that were damaged by this type of rain. His studies linked industries emissions with the source of it & also contained the early monitoring of harmful environment effects.

Types of Acid Deposition:

Acid rain is also called acid deposition. This deposition of acids may be dry or wet. Snow, rain & fog are wet deposition. When air takes  the acid chemicals into such an area that has wet weather then acid on the ground falls in the form of water flows through the ground and affects the diversity of animals and plants.

Acidic particles and gases are called dry deposition. Towards cars, buildings, homes & trees, these acidic particles & gases are blown by wind which results in sticking of these chemicals with the material.


The primary causes of acid rain are Nitrogen oxide, Sulphur dioxide & Ozone. Emission of these Sulphur dioxide & Nitrogen oxide pollutants causes acid deposition. These environment pollutants come from various activities of humans such as combustion of fossil fuels, thermal power plants. 

Effects of Acid Rain :-

It occurs due to the emission of Sulphur dioxide & nitrogen oxide & exerts various effects on.

  • Forests

Forests are severely damaged by acid rain. Trees at high altitudes are at greater risk because they are washed in acid clouds due to which spruce forests decline in number on the highest ranges of the Appalachian mountains.

  • Building and Monuments

Marble &  Limestone which make monuments & buildings are consisting of calcium carbonates which are worn by acid rain.  In acid rain, Sulphur dioxide provides aqueous ions by the dissolution of calcium carbonates.

  • Physiological activities of animals

Various metabolic activities of animals are affected by it. For example, brown trout is very sensitive to it, & in females; its sexual behaviour is extremely affected by it. Some troubles have also been seen in the immune system due to this kind of rain.

  • Soil

It can damage the chemistry of the soil & changes the soil Quality. Some harmless minerals such as Aluminium & Mercury are present in the soil to which plants cannot absorb when they react with the acids, then they become easily available to plants for absorption & changes the soil biology & chemistry as well as cause harmful effects.

  • Plants

Acid rain greatly affects the plants & crops by affecting its structural features. Trees are subjected to winter injury & even death when from the plant’s needles, calcium is leached out. Low pH decrease photosynthesis & also reduces the productivity of plant such as Soya bean.

  • Human Health

The appearance & taste of acid rain are just like clean water. It exerts indirect effects on human health. Acid rain causes the leaching of toxins from the soil, these toxins include AI, Mn, Fe, Pb, & Hg.

  •  Acid Rain & Climate Change 

It has an association with the climate. The emission of Sulphur dioxide, Nitrogen dioxide & Carbon dioxide causes acid rain. Carbon dioxide is a primary gas that also leads to the greenhouse effect. Human activities produce these chemicals of acid rain which reach the atmosphere, when their concentration becomes high then the temperature of the atmosphere, when their concentration becomes high then the temperature of the  atmosphere increases & results in climate warming.

  • Aquatic Ecosystem

Heavy metals which are leached out from the soil through the acid rain, reached to nearby lakes & streams & cause water pollution. These acids lower  the pH  of water bodies. Due to which reproduction of plants & animals is also affected. They are harm the animals which feed on these plants. It denatures the enzymes of microbes in the soil & killed them due to their intolerance at low pH.

Control of Acid Rain :-

It can be controlled through the followings ways.

  • Liming

It is a process that is used to neutralize the acids by adding limestone into the lakes, water & soils & reduces the lethal effects of heavy metals. This method can be applied to a specific area. 

Liming also allows the survival of the native population of fishes in ponds. The addition of lime reduces the damage to the water bodies. The pH of acidic water is raised by the addition of slacked lime, Caustic Soda, limestone & sodium carbonates. In water bodies, liming enhances the water quality. 

  • Reduce the emission of pollutants

Acid rain can be controlled by reducing the emission of pollutants such as Sulphur dioxide & nitrogen oxide which causes acid rain.

  • Policy Intervention

In Europe & the United States, during the 1970s & 1980s, acid rain effects on various natural resources were a serious issue. In 1980, the environment protection agency in the state of Canada took the action to control the emission of chemicals which causes it. Then, In 1990, Legislations to control acid rain effects & control program of acid rain was also introduced. The major aim of this program was to reduce the emission of Sulphur dioxide & nitrogen oxide to achieve health benefits for the environment & the public. 

Blog By:

Suman Chanwaria

Student of M.Sc. (Previous) Chemistry

Biyani Group of Colleges, Jaipur

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