Investigating Air Pollution
There are many different types of air pollutant. These pollutants have
different effects on the environment and on our health. Some, directly
because they are harmful chemicals and others because they can react
together to produce harmful chemicals. Other pollutants or pollutant
combinations upset the natural balance of acidity and nitrogen in the
environment which can affect the diversity of species in sensitive
areas. Other pollutants can contribute to changing global conditions
and potentially give rise to dramatic changes in climate and sea
Main Air Pollutants
Sulphur dioxide is an acidic gas which combines with water vapour in
the atmosphere to produce acid rain. Both wet and dry deposition have
been implicated in the damage and destruction of vegetation and in the
degradation of soils, building materials and watercourses. SO2 in
ambient air can also affect human health, particularly in those
suffering from asthma and chronic lung diseases.
The principal source of this gas is power stations burning fossil
fuels which contain sulphur. Major SO2 problems now only tend to occur
in cities in which coal is still widely used for domestic heating, in
industry and in power stations
Particles. Airborne particulate matter varies widely in its physical
and chemical composition, source and particle size. PM10 particles
(the fraction of particulates in air of very small size (<10 µm)) are
of major current concern, as they are small enough to penetrate deep
into the lungs and so potentially pose significant health risks.
Larger particles meanwhile, are not readily inhaled, and are removed
relatively efficiently from the air by sedimentation. The principal
source of airborne PM10 matter in European cities is road traffic
emissions, particularly from diesel vehicles.
Carbon monoxide (CO) is a toxic gas which is emitted into the
atmosphere as a result of combustion processes, and is also formed by
the oxidation of hydrocarbons and other organic compounds. In European
urban areas, CO is produced almost entirely (90%) from road traffic
emissions. It survives in the atmosphere for a period of approximately
one month but is eventually oxidised to carbon dioxide (CO2).
Nitrogen Dioxide. Nitrogen oxides are formed during high temperature
combustion processes from the oxidation of nitrogen in the air or
fuel. The principal source of nitrogen oxides - nitric oxide (NO) and
nitrogen dioxide (NO2), collectively known as NOx - is road traffic,
which is responsible for approximately half the emissions in Europe.
NO and NO2 concentrations are therefore greatest in urban areas where
traffic is heaviest. Other important sources are power stations,
heating plants and industrial processes.
Ground-level ozone (O3), unlike other pollutants mentioned , is...