Acid Rain

Context:

Acid rain has its origin in fossil fuels

Acid Rain:

• Broad concept that includes any form of precipitation that contains acidic components of sulphuric and nitric acid that comes in wet or dry form
• Forms of acid rain –
  • Wet deposition – rain, sleet, snow , fog  or hail acidic than normal
  • Dry deposition – gasses or dust particles acidic than normal
• Causes – SO2 and NO_x emissions, Fossil fuel burning, formation of acid precursors in atmosphere etc.
• Effects – harmful to terrestrial and aquatic organisms (skin disease), threat to buildings (colour change), corrosion, lower visibility etc.
• Mitigation measures – reducing SO from coal plants using desulphurisation, restoring acid rain damage through liming process, Graded Response Action Plan etc.
• Government Initiatives –
  • BS-VI vehicles
  • New Commission for Air Quality Management
  • Air Quality and Weather Forecasting and Research (SAFAR)
  • National Air Quality Index (AQI)
  • Air (Prevention and Control of Pollution) Act, 1981
• International Corporation –
  • Acid Deposition Monitoring Network in East Asia (EANET).

Acid fog – an air borne pollutant, primarily acidic in nature, form a mist/fog that can have corrosive effects on surfaces and ecosystems.

Flue-Gas Desulphurisation:

• Used to remove sulfur dioxide (SO2) from flue gases
• Technology – using wet scrubbing or dry scrubbing in the waste exhausts
• Aim – To reduce sulphur dioxide emissions by more than 90%.

Graded Response Action Plan (GRAP):

• Set of emergency measures that kick in to prevent further deterioration of air quality once it reaches a certain threshold in the Delhi-NCR region.

Liming process:

• Process of adding acid-neutralizing substances (usually powdered lime or limestone) into the affected lake or river.
• The lime neutralizes the acid raising the pH of the water and protects some fish from effects of metals.

Acid Deposition Monitoring Network in East Asia (EANET):

• An intergovernmental initiative
• Established in 2001
• To create a common understanding on the state of acid deposition problems in East Asia
• Provides useful inputs for decision making at various levels, and promote cooperation among countries.

Read more about:  National Air Quality Index (AQI),  Air Pollution, Government Initiatives

Source: The Hindu

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Previous Year Question

In the context of WHO Air Quality Guidelines, consider the following statements:
1. The 24-hour mean of PM2.5 should not exceed 15 μg/m³ and annual mean of PM2.5 should not exceed 5 μg/m³.
2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather.
3. PM10 can penetrate the lung barrier and enter the bloodstream.
4. Excessive ozone in the air can trigger asthma.
Which of the statements given above are correct?

[UPSC Civil Services Exam – 2022 Prelims]

(a) 1, 3 and 4
(b) 1 and 4 only
(c) 2, 3 and 4
(d) 1 and 2 only

Answer: (b)
Explanation:
Statement 2 is not correct:
In a year, the highest levels of ozone pollution occur during the periods of summer weather (sunny weather)
Statement 3 is not correct:
PM₁₀ can pass through throat and nose and reach lung barrier whereas PM_2.5 can even enter the bloodstream.

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