Problems with Air Quality

Air quality problems arise mainly from pollutants released into the atmosphere by human activities. These pollutants can harm human health, damage the environment, and reduce visibility. This note covers the health effects, environmental impacts, sources of pollution, and control measures to improve air quality.

Health Effects of Poor Air Quality

Poor air quality caused by atmospheric pollution can have serious effects on human health. Breathing in polluted air can irritate the respiratory system, leading to problems such as coughing, wheezing, and shortness of breath. It can also aggravate existing conditions like asthma, making attacks more frequent and severe.

Air pollution is linked to cardiovascular issues because some pollutants enter the bloodstream through the lungs. This can increase the risk of heart attacks, strokes, and other heart-related diseases.

For instance, particulate matter (tiny solid or liquid particles suspended in air) can penetrate deep into the lungs and bloodstream, triggering inflammation and worsening heart and lung diseases.

Example: If a person with asthma is exposed to high levels of air pollution, their airways can become inflamed, causing difficulty in breathing and increased use of inhalers.

Environmental Impact

Air pollution damages ecosystems in several ways. Pollutants can harm plants, animals, and entire habitats by contaminating soil and water.

Acid rain is a major environmental problem caused by sulfur dioxide (SO₂) and nitrogen oxides (NO_x) reacting with water in the atmosphere to form acidic compounds. Acid rain lowers the pH of soil and water, harming plants, fish, and other wildlife.

Another effect of air pollution is reduced visibility, often seen as smog. Smog forms when pollutants like particulates and nitrogen oxides react under sunlight, creating a thick haze that reduces sunlight and can disrupt ecosystems. Smog is a photochemical haze different from acid rain, caused mainly by chemical reactions involving sunlight.

Example: Acid rain falling on a forest can damage leaves and roots, weakening trees and making them more susceptible to disease and harsh weather.

Sources of Air Pollution

Several pollutants contribute to poor air quality. Key sources include:

• Particulates: Tiny solid particles or liquid droplets released from burning fuels, especially diesel engines and coal power stations.
• Nitrogen oxides (NO_x): Gases produced when nitrogen and oxygen react at high temperatures in vehicle engines and power stations.
• Sulfur dioxide (SO₂): Formed when fossil fuels containing sulfur, like coal and oil, are burned.
• Carbon monoxide (CO): A colourless, odourless gas produced by incomplete combustion of fuels, especially in car engines.

These pollutants come mainly from human activities such as transport, industry, and domestic heating.

Example: Diesel vehicles emit particulates and nitrogen oxides, which contribute to smog and respiratory problems in cities.

Air Quality Control Measures

To reduce air pollution and improve air quality, several control measures are used:

• Emission limits: Governments set legal limits on the amount of pollutants that vehicles and factories can release.
• Catalytic converters: Devices fitted to car exhausts that convert harmful gases like carbon monoxide and nitrogen oxides into less harmful substances such as carbon dioxide and nitrogen.
• Alternative energy sources: Using renewable energy (solar, wind, hydroelectric) or cleaner fuels (electric vehicles, hydrogen) reduces reliance on fossil fuels and lowers pollution.

These measures help protect human health and the environment by limiting the release of harmful pollutants.

Example: Catalytic converters in petrol cars convert carbon monoxide (CO) into carbon dioxide (CO₂), which is less harmful to breathe.

For example, if a car emits 0.5 g of carbon monoxide per kilometre, then on a 150 km journey it emits:

$0.5 \text{ g/km} \times 150 \text{ km} = 75 \text{ g}$