Impact of atmospheric pollution Revision Notes

Smog is a type of air pollution formed when sunlight reacts with pollutants such as nitrogen oxides and volatile organic compounds emitted by vehicles and industrial processes. This reaction produces a visible haze composed mainly of ozone and fine particulate matter.

Smog irritates the respiratory system, causing problems such as coughing, throat irritation, and difficulty breathing. People with asthma or other lung conditions are especially vulnerable. For example, in large cities like Los Angeles, smog episodes have led to increased hospital admissions for respiratory illnesses.

The health impact arises because smog particles penetrate deep into the lungs, reducing lung function and increasing the risk of respiratory infections. Long-term exposure can worsen chronic respiratory diseases and reduce overall lung capacity.

• Formed by chemical reactions between pollutants and sunlight.
• Contains ozone and fine particles harmful to lungs.
• Causes respiratory problems, especially in vulnerable groups.

Acid rain forms when sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) released by burning fossil fuels react with water vapour in the atmosphere to produce sulfuric and nitric acids. These acids fall to the ground as rain, snow, or fog with a pH lower than normal rainwater.

When acid rain enters lakes and rivers, it lowers the pH of the water, making it acidic. This acidification harms aquatic life, particularly fish species sensitive to pH changes, such as trout and salmon, which may die or fail to reproduce.

Acid rain also damages crops and natural vegetation by leaching essential nutrients from the soil and releasing toxic metals. Buildings and monuments made of limestone or marble suffer chemical erosion, leading to structural damage and loss of cultural heritage. For example, acid rain has visibly eroded statues in European cities.

• Caused by SO₂ and NOₓ reacting with water to form acids.
• Acidifies water bodies, harming fish populations.
• Damages crops and vegetation by nutrient depletion and toxicity.
• Erodes buildings made of carbonate rocks.

The ozone layer in the stratosphere absorbs most of the Sun's harmful ultraviolet (UV) radiation. Certain human-made chemicals, such as chlorofluorocarbons (CFCs), break down ozone molecules, thinning this protective layer.

Ozone depletion results in more UV radiation reaching the Earth's surface. Increased UV exposure raises the incidence of skin cancers and cataracts in humans by damaging DNA and eye tissues.

Plants are also affected; excessive UV radiation can reduce photosynthesis, impair growth, and lower crop yields. For instance, crops like wheat and soybeans show reduced productivity under high UV conditions.

• Ozone layer absorbs harmful UV radiation.
• CFCs cause ozone molecules to break down, thinning the layer.
• More UV radiation increases skin cancer and cataracts.
• Plants suffer reduced growth and photosynthesis.

Climate change is driven by increased greenhouse gases, such as carbon dioxide, trapping heat in the atmosphere and raising global temperatures.

Rising temperatures cause ice sheets, glaciers, and permafrost to melt. This melting contributes to rising sea levels, which increase the risk of coastal flooding and loss of land. Low-lying areas and small island nations are particularly vulnerable.

Flooding from sea level rise can force people to migrate inland, creating environmental refugees. Additionally, thawing permafrost releases methane, a potent greenhouse gas, which can further accelerate warming in a feedback loop.

• Greenhouse gases cause global temperature rise.
• Melting ice and permafrost contribute to sea level rise.
• Sea level rise leads to flooding and land loss.
• Flooding forces migration and can worsen climate change via methane release.