A3.4.1 Adverse Effects of Pollution on Air


Some of the issues relating to air pollution have already been discussed earlier.

Major sources of air pollution relate to the combustion of fossil fuels. Whilst this is a less common practice in the UK, where the environmental effects are understood and legislation is in place to control the effects, other countries are relying heavily on coal fired power stations as they develop. For example, in 2007 the BBC reported that “China is now building about two power stations every week”.

Another key source of air pollutants is traffic emissions. Petrol and diesel engines in vehicles emit a wide variety of pollutants, including carbon monoxide (CO), oxides of nitrogen (NOx), volatile organic compounds (VOCs) and particulates (PM10).

These all have an increasing impact on urban air quality. In addition, they contribute to acid deposition and the formation of Ground Level Ozone.

Acid Deposition

Acid Deposition is commonly referred to as acid rain. Industrial processes emit air pollutants.

In some instances these are large particles, which will fall out of the atmosphere near to the source of the emission.

In other instances, smaller particles are carried through the atmosphere until they are ‘washed out’ by rain. The rain returns these pollutants to us, usually in the form of a dilute sulphuric or nitric acid. The deposition may occur hundreds of miles from the source of pollution, making acid rain a transboundary pollutant.

The impact depends upon where the rain lands. For example, if it lands in water bodies it acidifies the water body, which will damage plants and aquatic habitats. If it lands on buildings it can cause corrosion. If it lands on soil it will increase the acidity of the soil, again damaging plants, and also damaging terrestrial habitats. If the deposition is long-term, the acidity of the soil may be permanently changed, which will mean only certain tolerant plants can survive.

Ground Level Ozone

Ground Level Ozone (the ‘bad ozone’ mentioned earlier) is caused by photochemical reactions (reactions resulting from the action of sunlight) on Nitrogen Dioxide and VOCs.

Ground-level ozone damages lung function, particularly in children and asthmatics. Ozone also causes leaf injury in plants, including crops and trees, and causes mainly organic materials like paint or rubber to disintegrate.