What is 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 level.
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) ...
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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 not emitted directly into the atmosphere, but is a secondary pollutant produced by reaction between nitrogen dioxide (NO2), hydrocarbons and sunlight. Ozone levels are not as high in urban areas (where high levels of NO are emitted from vehicles) as in rural areas. Sunlight provides the energy to initiate ozone formation; consequently, high levels of ozone are generally observed during hot, still sunny, summertime weather.
Volatile Organic Compounds. VOCs are released in vehicle exhaust gases either as unburned fuels or as combustion products, and are also emitted by the evaporation of solvents and motor fuels.
Benzene is a VOC which is a minor constituent of petrol. The main sources of benzene in the atmosphere in Europe are the distribution and combustion of petrol. Of these, combustion by petrol vehicles is the single biggest source (70% of total emissions).
1,3-butadiene, like benzene, is a VOC emitted into the atmosphere principally from fuel combustion of petrol and diesel vehicles. 1,3-butadiene is also an important chemical in certain industrial processes, particularly the manufacture of synthetic rubber.
TOMPs (Toxic Organic Micropollutants) are produced by the incomplete combustion of fuels. They comprise a complex range of chemicals some of which, although they are emitted in very small quantities, are highly toxic or carcinogenic. Compounds in this category include:
· PAHs (PolyAromatic Hydrocarbons)
· PCBs (PolyChlorinated Biphenyls)
· Dioxins
· Furans
Lead and Heavy Metals. Particulate lead in air results from activities such as fossil fuel combustion (including vehicles), metal processing industries and waste incineration. Its single largest industrial use world-wide is in the manufacture of batteries.
As tetraethyl lead, it has been used for many years as an additive in petrol; most airborne emissions of lead in Europe therefore originate from petrol-engined motor vehicles. With the increasing use of unleaded petrol, however, emissions and concentrations in air have declined steadily in recent years.
Acid Deposition. When power stations, factories, houses and cars emit pollution into the air, it contains chemicals known as sulphur dioxide and nitrogen oxides. These chemicals may either fall directly back to the Earth due to gravity, or they may mix with water (moisture) in the air to form acids. Once acids have formed, they can be transported long distances by the wind before being deposited in rain, snow or hail. This is what we commonly call acid rain. Acid rain can have harmful impacts on the environment. It affects freshwater lakes and the wildlife that depend upon them. It also affects trees by harming leaves and soil, and it damages buildings made of limestone and marble.
Air Pollution Affecting Health
Sulphur Dioxide. Even moderate concentrations may result in a fall in lung function in asthmatics. Tightness in the chest and coughing occur at high levels, and lung function of asthmatics may be impaired to the extent that medical help is required. Sulphur dioxide pollution is considered more harmful when particulate and other pollution concentrations are high.
Particles. Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of the condition of people with heart and lung diseases. In addition, they may carry surface-absorbed carcinogenic compounds into the lungs.
Carbon Monoxide. This gas prevents the normal transport of oxygen by the blood. This can lead to a significant reduction in the supply of oxygen to the heart, particularly in people suffering from heart disease.
Nitrogen dioxide. Can irritate the lungs and lower resistance to respiratory infections such as influenza. Continued or frequent exposure to concentrations that are typically much higher than those normally found in the ambient air may cause increased incidence of acute respiratory illness in children.
Ozone. Irritates the airways of the lungs, increasing the symptoms of those suffering from asthma and lung diseases.
VOCs. Possible chronic health effects include cancer, central nervous system disorders, liver and kidney damage, reproductive disorders, and birth defects
TOMPS. Can cause a wide range of effects, from cancer to reduced immunity to nervous system disorders and interfere with child development. There is no "threshold" dose - the tiniest amount can cause damage.
Lead and Heavy Metals. Even small amounts of lead can be harmful, especially to infants and young children. In addition, lead taken in by the mother can interfere with the health of the unborn child. Exposure has also been linked to impaired mental function, visual-motor performance and neurological damage in children, and memory and attention span.
What can the community do about air pollution?
When it comes to the environment, even the smallest individual action really does make a difference - and can benefit you too! There are many easy changes we can all make to our everyday lives to help protect and improve our environment - it just involves a little bit of extra thought about our day-to-day actions and how they impact on the environment.
Local pollution, such as car fumes, can aggravate asthma and cause premature deaths in those seriously ill. But you can help by, where possible, not using your car for short journeys, sharing car journeys with friends and family and having your car serviced regularly.
Pollution is also affecting the whole world. The burning of fuel in power stations and oil refineries provides you with the energy you use in your home and car. This burning of fuel also pumps out 'greenhouse gases' which cause global warming. In the UK this could mean more floods and storms, drier summers and wetter winters. You can do your bit to help the environment, and save money at the same time, by saving energy and resources.
