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Air Pollution and the Greenhouse Effect
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Air Pollution and the Greenhouse Effect
Air Pollution and the Greenhouse Effect
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Question
What is the greenhouse effect and how does it contribute to climate change?
Answer
The greenhouse effect is a natural process where gases like CO₂, CH₄, and H₂O trap heat in the Earth's atmosphere. Sunlight enters freely, but heat radiated back from the Earth is absorbed and re-emitted by greenhouse gases, warming the surface. While essential for life, increased greenhouse gases from human activities enhance this effect, causing global warming, disrupted weather patterns, melting ice, rising sea levels, and extreme weather events.
Question
Define air pollution and list major natural and anthropogenic sources.
Answer
Air pollution is the presence of foreign substances in the atmosphere at harmful concentrations and durations, affecting health, property, or the environment. Natural sources include volcanic eruptions (SO₂, CO₂, ash), forest fires (CO, CO₂, hydrocarbons), and dust storms. Anthropogenic sources include industrial emissions (PM, SO₂, NOx), power plants (SOx, NOx, CO₂), vehicle emissions (CO, NOx, VOCs, PM), and waste burning (PAHs, PM, VOCs, CO).
Question
Distinguish between primary and secondary air pollutants with examples.
Answer
Primary pollutants are emitted directly from identifiable sources (e.g., CO, SO₂, NOx, PM, lead). Secondary pollutants form in the atmosphere by chemical reactions among primary pollutants or with atmospheric components (e.g., ozone (O₃), peroxyacetyl nitrate (PAN), photochemical smog, sulfuric acid). Primary sources include combustion engines and factories; secondary pollutants form via sunlight and chemical interactions.
Question
What are the six criteria air pollutants regulated by the US EPA and India’s NAAQS?
Answer
The six criteria air pollutants are: 1) Particulate Matter (PM₁₀ and PM₂.₅), 2) Ground-level Ozone (O₃), 3) Carbon Monoxide (CO), 4) Sulfur Dioxide (SO₂), 5) Nitrogen Dioxide (NO₂), and 6) Lead (Pb). They are regulated due to their significant health and environmental risks and serve as air quality indicators.
Question
Explain the role of greenhouse gases in the mechanism of the greenhouse effect.
Answer
Solar radiation passes through the atmosphere and warms the Earth's surface, which re-emits energy as infrared radiation. Greenhouse gases absorb and re-emit some of this infrared radiation back to the surface, trapping heat and warming the planet. Key greenhouse gases include CO₂ (from fossil fuel combustion and deforestation), CH₄ (from agriculture and landfills), N₂O (from fertilizers), CFCs (from refrigerants), and water vapor.
Question
Classify air pollutants based on origin, chemical composition, and physical state with examples.
Answer
Based on origin: Primary (directly emitted, e.g., CO, SO₂, NOx, PM) and Secondary (formed in atmosphere, e.g., O₃, PAN). Chemical composition: Organic (hydrocarbons, aldehydes) and Inorganic (CO, NOx, SO₂, Pb). Physical state: Particulate (solid/liquid particles like dust, smoke) and Gaseous (CO, SO₂, NO₂, O₃).
Question
Describe the major air pollution episode known as the Great London Smog of 1952.
Answer
Caused by cold weather leading to increased coal burning which released high SO₂ and particulate matter. A temperature inversion trapped pollutants near the surface within calm conditions, preventing dispersion. Resulted in severe visibility reduction, over 4,000 deaths in a few days, and thousands more later. It triggered the UK's Clean Air Act (1956) and caused severe respiratory illnesses, especially in vulnerable groups.
Question
List three health effects of exposure to ozone and sulfur dioxide.
Answer
Ozone causes respiratory irritation (coughing, throat irritation), aggravates asthma and other lung diseases, reduces lung function, and increases infection susceptibility. Sulfur dioxide irritates mucous membranes (eyes, nose, throat), triggers asthma attacks and bronchial constriction, can cause chronic respiratory illness, and contributes to acid rain formation.
Question
Explain the health effects of particulate matter (PM) on humans.
Answer
PM, especially fine particles (PM2.5, PM10), can penetrate deep into the lungs causing respiratory irritation like coughing and shortness of breath, trigger asthma and bronchitis attacks, increase morbidity and mortality in people with heart or lung conditions, cause occupational lung diseases (silicosis, asbestosis), some particles can be carcinogenic, and carry heavy metals like lead that cause systemic toxicity.
Question
What are the sources and health effects of indoor air pollution?
Answer
Indoor air pollution sources include cigarette smoke, mold, radon gas, carbon monoxide from faulty appliances, pet dander, asbestos in old materials, and formaldehyde from pressed wood. Health effects include Sick Building Syndrome (headaches, irritation, fatigue), respiratory diseases (COPD, lung cancer), and exposure to toxins or radioactive gases leading to serious illness.
Question
Discuss the Bhopal Gas Tragedy: cause, pollutant released, and impacts.
Answer
The Bhopal Gas Tragedy (1984) was caused by an accidental leak of methyl isocyanate (MIC) gas from the Union Carbide plant. The toxic release caused about 2,000 immediate deaths officially, with an estimated 15,000 long-term deaths and over 300,000 injured people suffering respiratory, neurological, and reproductive problems. It raised global awareness about industrial safety and emergency responses.