Air Quality Management
What is Air Pollution ?
Air pollution is caused by extremely fine dust particles and gases in the air which can cause harm if you breathe them in.
Poor air quality is the largest environmental risk to public health and is estimated to kill over 40,000 people a year in the UK alone. Long-term exposure to air pollution can cause chronic conditions such as cardiovascular and respiratory diseases as well as lung cancer, leading to reduced life expectancy. Short-term exposure (over hours or days) to elevated levels of air pollution can also cause a range of health impacts, including effects on lung function, exacerbation of asthma, increases in respiratory and cardiovascular hospital admissions and mortality. In 2010, the British Government's Environment Audit Committee considered that the cost of health impacts of air pollution was likely to exceed estimates of £8 to 20 billion.
How Air Pollution Harms Health ?
When pollutants enter the body what they do ? When air pollutants enter the body, they can have effects on various different organs and systems, not just the respiratory system.
This includes:
the eyes, nose and throat
the lungs and respiratory system
the heart – heart and blood vessel diseases, including strokes and hardening of the arteries, are one of the main effects of air pollution
Emerging evidence suggests that air pollution may also affect the brain and is possibly linked to dementia and cognitive decline. There is also emerging evidence associating air pollution with early life effects such as low birth weight.
Impact of Air Pollution across a Person’s Lifetime
Air pollution can affect everyone, and air in all areas of the UK contains some proportion of man-made air pollutants. Exposure to air pollution has various different health effects, which come about at every stage of life, from a foetus’ first weeks in the womb all the way through to old age. The health effects of air pollution are complex, and range in severity of impact. In some cases, damage can be gradual and may not become apparent for many years.
The 3 main conditions associated with air pollution are respiratory conditions (such as asthma), cardiovascular disease (CVD), and lung cancer, and there is emerging evidence for associations with dementia, low birth weight and Type 2 diabetes. COMEAP (Committee on the Medical Impacts of Air Pollutants) has highlighted that exposure to air pollution contributes to many thousands of deaths in the UK, through increasing the risk of CVD, respiratory disease and cancers.
Introduction to National Air Quality Strategy
In May 1997 the Government produced the National Air Quality Strategy (NAQS). The strategy represents a comprehensive approach to maintaining and improving the quality of ambient air in the United Kingdom. Outlined in the strategy are the air quality objectives for the 8 pollutants the Government feels are of most concern at present and the dates it feels these targets should be met.
PM10 Particulates
PM10 describes the fraction of airborne particulate matter that is less than 10 microns in size. Fine particles are of the greatest concern since they are capable of being easily transported over long distances on currents of air. Also, fine particles may be drawn into the respiratory airways where they may adversely affect health. Recently, the attention of scientists has been drawn towards studying the PM2.5 fraction and even smaller particles, which can penetrate the very deepest parts of the lung.
PM10 and other particulate matter may vary considerably in chemical and physical composition. The principal sources of these particles are combustion processes, including traffic and industry.
Nitrogen Dioxide(NO2)
Nitrogen dioxide is one of a number of nitrogen oxides, which are formed during high temperature combustion processes. Road traffic is the main source, accounting for
approximately 50% of all European emissions. Therefore, concentrations tend to be highest in urban environments with high traffic levels. Large industrial sources can also have a significant impact.
Nitrogen dioxide is a respiratory irritant and also plays a part in the production of another atmospheric pollutant, Ozone. Nitrogen oxides remain in the atmosphere for approximately one day before they are oxidised to nitric acid. Nitrogen oxides are therefore a contributory factor in the production of acid rain.
Air quality is monitored for Nitrogen Dioxide at various sites across the County.
Ozone(O3)
Ozone is a very reactive chemical, which is potentially toxic to both plants and animals. In the Stratosphere, ozone helps to protect the earth from the harmful effects of ultra-violet rays from the sun. However at ground level it is a pollutant. Unlike the other pollutants mentioned above, ozone is not emitted directly. Rather, it is formed as a result of a complex series of reactions involving hydrocarbons, sunlight and nitrogen dioxide (NO2). The involvement of sunlight in this process means that ozone levels tend to be highest in summer. The reactions take time to generate ozone and the highest concentrations are frequently experienced many miles away from the source of the pollution, perhaps in rural areas. In fact, a significant proportion of ozone incidents experienced in the UK are due to pollution imported from abroad. The problem of ozone pollution can therefore only be adequately dealt with as a result of international agreements.
Common atmospheric pollutants
NO2 is a gas that is produced along with nitric oxide (NO) by combustion processes. Together they are often referred to as oxides of nitrogen (NOx).
The Department for Environment, Food & Rural Affairs (Defra) estimates that 80% of NOx emissions in areas where the UK is exceeding NO2 limits are due to transport, with the largest source being emissions from diesel light duty vehicles (cars and vans). Other sources include power generation, industrial processes, and domestic heating.
The Committee on the Medical Effects of Air Pollutants (COMEAP) has established that short-term exposure to NO2, particularly at high concentrations, is a respiratory irritant that can cause inflammation of the airways leading to - for example - cough, production of mucus and shortness of breath. Studies have shown associations of NO2 in outdoor air with reduced lung development, and respiratory infections in early childhood and effects on lung function in adulthood.
Epidemiological studies have also shown associations of outdoor NO2 with adverse effects on health, including reduced life expectancy. It has been unclear whether these effects are caused by NO2 itself, or by other pollutants emitted at the same time by sources such as road traffic.
PM is a generic term used to describe a complex mixture of solid and liquid particles of varying size, shape, and composition. Some particles are emitted directly (primary PM); others are formed in the atmosphere through complex chemical reactions (secondary PM). The composition of PM varies greatly and depends on many factors, such as geographical location, emission sources and weather.
The main sources of man-made PM are the combustion of fuels (by vehicles, industry and domestic properties) and other physical processes such as tyre and brake wear. Natural sources include wind-blown soil and dust, sea spray particles, and fires involving burning vegetation.
PM is often classified according to by aerodynamic size and referred to as:
- coarse particles (PM10; particles that are less than 10 microns (µm) in diameter)
- fine particles (PM2.5; particles that are less than 2.5 µm in diameter)
- ultrafine particles (PM0.1; particles that are less than 0.1 µm in diameter)
The size of particles and the duration of exposure are key determinants of potential adverse health effects. Particles larger than 10 µm are mainly deposited in the nose or throat, whereas particles smaller than 10 µm pose the greatest risk because they can be drawn deeper into the lung. The strongest evidence for effects on health is associated with fine particles (PM2.5).
There is an extensive body of evidence that long-term exposure to PM increases mortality and morbidity from cardiovascular and respiratory diseases. Outdoor air pollution, particularly PM, has also been classified by the International Agency for Research on Cancer (IARC) as carcinogenic to humans (a Group 1 carcinogen) and causing lung cancer. There is some experimental evidence, however, that ultrafine particles may also pass through the lungs into the bloodstream.
SO2 is produced when sulphur-containing fuels, such as coal, are burned. It is an invisible gas with a sharp smell and can dissolve in water. Chemical reactions of SO2 can also produce sulphates, which remain in the air as secondary particles, contributing to the PM mix.
SO2 has an irritant effect on the lining of the nose, throat and airways, and the effects are often felt very quickly. Due to the increased use of gas and electricity, coal-burning is now relatively uncommon, and levels of SO2 have steadily declined over the last 50 years. Most SO2 in the UK now comes from industrial sources, such as coal and oil-burning power stations, as well as domestic sources such as boilers and stoves.
NH3 is a gas released into the atmosphere from natural and man-made sources. Once emitted into the atmosphere, the subsequent deposition of NH3 can be a major source of pollution, causing nitrogen (N) enrichment (eutrophication) and acidification of soil and water sources. Atmospheric NH3 also reacts with acid gases, such as sulphuric and nitric acid, to form secondary PM2.5.
The main health impacts of NH3 arise through its role in secondary PM2.5 formation and health effects associated with exposure to PM, as described above. Thus, NH3 not only plays a role in acidification and eutrophication but also contributes to the overall PM burden. Agricultural emissions of NH3 have been reported to be key contributor to some short-term episodes of high PM pollution in recent years.
CO is a colourless, odourless and tasteless gas, produced when fuels such as gas, oil, coal and wood burn without enough oxygen. These are sources of fuel used in many household appliances, including boilers, central heating systems, gas fires, water heaters, cookers and open fires. Burning charcoal, running cars and the smoke from cigarettes also produce CO gas.
Exposure to high indoor levels can be fatal, while exposure to lower levels can result in symptoms that resemble flu, viral infections or food poisoning.
Ozone is a very reactive chemical, which is potentially toxic to both plants and animals. In the stratosphere, ozone helps to protect the earth from the harmful effects of ultra-violet rays from the sun. However at ground level it is a pollutant.
Unlike the other pollutants mentioned above, ozone is not emitted directly. Rather, it is formed as a result of a complex series of reactions involving hydrocarbons, sunlight and nitrogen dioxide (NO2).
The involvement of sunlight in this process means that ozone levels tend to be highest in summer. The reactions take time to generate ozone and the highest concentrations are frequently experienced many miles away from the source of the pollution, perhaps in rural areas. In fact, a significant proportion of ozone incidents experienced in the UK are due to pollution imported from abroad.
The problem of ozone pollution can therefore only be adequately dealt with as a result of international agreements