Understanding Air Pollution: Causes and Impacts

Item 11: Impacts in the Atmosphere

Sources of Air Pollution

Natural Sources

Natural sources are more significant than those related to human beings, but they are spread around the planet:

• Volcanic eruptions: Emit sulfur compounds, carbon, nitrogen, and suspended particles.
• Natural forest fires: Release CO2.
• Finest sediment particles: They are lifted by wind in areas of low vegetation, such as deserts.

Anthropogenic Sources

Anthropogenic sources result from human activity. Artificial sources can release pollutants but also promote natural emissions.

Among them are transport, industrial processes, and household heating.

Local Effects of Air Pollution

Photochemical Smog

Photochemical smog can be defined as a mixture of toxic substances formed in the lower layers of the troposphere.

It is formed when hydrocarbons, nitrogen oxides, and oxygen react to the action of ultraviolet radiation from the Sun. The products of this reaction are substances such as ozone. Factors that favor the appearance of photochemical smog are solar radiation, thermal inversion (a change in the normal behavior of the atmosphere layers), and relief.

Effects:

• Irritation of the respiratory system
• Mucous membrane irritation of the eyes
• Fatigue, headache, and decay

Preventive measures: Measures can be based on the promotion of public transport, using cleaner fuels, or the use of mechanisms that reduce vehicle exhaust gases.

Acid Rain

Acid rain can be defined as the wet deposition of sulfuric, nitric, carbonic, and hydrochloric acid on the surface.

High-temperature combustion produces nitrogen oxides when nitrogen and atmospheric oxygen combine. Coal and oil generate a smaller amount of these pollutants, and sulfur oxides first react with water and form clouds of sulfuric acid. This makes rainwater droplets acidic. When acid rain reaches the ground, it has harmful effects on aquatic and terrestrial ecosystems.

Cause: The main cause of this effect is power plants that burn coal.

Measures:

• Use clean coal
• Use of calcium carbonate
• Use of filters in chimneys

Global Effects of Air Pollution

The Greenhouse Effect

The greenhouse effect is the retention in the atmosphere of a portion of the heat emitted by the Earth's surface after it has warmed due to solar radiation. It delays the release of thermal energy into space.

The average temperature of the Earth increases as a result of the increasing greenhouse effect, and this is a scientifically proven fact.

Causes:

• Use of conventional energy
• Mass use of private transport that produces pollutant gases

Preventive measures: The measures are based mainly on the substitution of conventional energy with alternatives that do not pollute, the use of public transport, and energy saving.

Reduction of the Ozone Layer

This reduction refers to the area where the total amount of ozone gas falls below set levels. It is not called a hole but rather a thinning of the layer. The main contaminants are chlorinated compounds, methane, and nitrogen oxide, among others.

Air Quality

• Emission contaminants: The production and release of substances into the atmosphere.
• Emission levels: The amount of pollutants released by a specific source or globally.
• Immission levels: The concentration of pollutants in the air of a place at a specific moment, apart from the sources that have released them.