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Air Quality FAQ

What is Air Pollution?

Air is essential to life, but pollution of it can be detrimental to our health. Polluted air contains substances that can be harmful to health, quality of life or the environment. Air pollution can be as obvious as bonfire smoke, but in many cases has no smell and cannot be seen.

Where do the air pollutants come from?

Nitrogen Dioxide: Nitrogen dioxide (NO2) is a gas produced by the reaction of nitrogen and oxygen in the atmosphere. All combustion processes, such as vehicle engines, power stations and industries emit nitric oxide (NO) and nitrogen dioxide (NO2), collectively called oxides of nitrogen (i.e. NOx). Usually the dominant NOx emission is in the form of NO, which through chemical reactions in the atmosphere is converted to NO2. The main source of NOx emissions is from road transport both nationally and locally.

Particulate Matter: (PM10): Particulate matter can be emitted from a range of different sources both natural (e.g. pollen, fungal spores, sea salt etc) and human derived (e.g. road traffic, combustion processes, construction and quarrying). Particulate matter varies in its physical and chemical composition and particle size. PM10 (particles less than 10 mm) are currently of most concern since they are small enough to penetrate into the lungs, while larger particles are not readily inhaled. The main source of PM10 is road traffic, particularly diesel vehicles.

Sulphur Dioxide: Sulphur dioxide (SO2) is a colourless soluble gas. It is produced by the combustion of fossil fuels containing sulphur such as for industry, power stations and domestic heating. Since the burning of fossil fuels for domestic heating has rapidly declined over the last two decades the main source of SO2 in the UK is now from power stations.

Carbon Monoxide: Carbon monoxide (CO) is a colourless, odourless and tasteless gas, which arises during incomplete combustion of fossil fuels. The main source of CO is road traffic, particularly petrol driven vehicles. Levels are generally declining as the effect of catalytic converters outweighs increasing traffic volumes.

Benzene: Benzene (C6H6) is a volatile organic compound (VOC) and a minor component of petrol. It arises from petrol evaporation and combustion of other petrol components. In the UK, road vehicles are the principle source of C6H6 emissions particularly in urban areas.

1,3-Butadiene: 1,3-Butadiene (C4H6) is a VOC arising from the combustion process of petroleum products. In the UK, road vehicles are the principle source of C4H6 emissions particularly in urban areas.

Lead: Lead (Pb) is a heavy metal, which exists naturally, but its exploitation for activities such as fossil fuel combustion, metal industries and waste incineration can give rise to particulate lead in air. Previously in the UK the main source of Pb was from road vehicles but since the introduction of unleaded petrol in the late 1980s emissions have decreased significantly.

Will air pollution affect the health of my family and me?

National Air Quality Standards have been devised with health effects in mind. They have been set to protect the most vulnerable members of the population, although recent evidence suggests that health effects can occur at lower levels, particularly for finer particulates. Each air pollutant can have both short-term and long-term health effects.

Nitrogen Dioxide: The short-term health effects of Nitrogen Dioxide (NO2) include eye, nose and throat irritation and can also trigger the onset of symptoms of existing respiratory conditions such as asthma and bronchitis. Long-term health effects of NO2 are associated with gradual deterioration in health for susceptible people (e.g. the elderly and those already suffering from respiratory problems), can lower resistance to respiratory infections such as influenza and can increase the rate of acute respiratory illness in children.

Particulate Matter (PM10): Particles inhaled by humans are separated by size during deposition within the respiratory system, larger particles depositing in the upper part of the respiratory system and smaller particles penetrating deeper into the lungs. Small particles can cause inflammation and a worsening of existing heart and lung conditions. They can also carry surface-absorbed carcinogenic compounds into the lungs. Evidence has shown that rises in PM10 levels may be associated with an increase in hospital admissions, increases in reported symptoms of existing respiratory conditions, such as COPD and asthma and decreases in lung function.

Sulphur Dioxide: Sulphur Dioxide (SO2) is recognised as a potent respiratory irritant. Even moderate concentrations can result in a fall in lung function in asthmatics. At high levels, chest tightness, coughing and impaired lung function of asthmatics to the point that medical attention is required may occur. .SO2 is considered to be more harmful when associated with high concentrations of other pollutants. Currently in Swale Borough, SO2 is not at levels that of any cause for concern to health.

Carbon Monoxide: Carbon Monoxide (CO) can interfere with the normal transport of oxygen by the blood, which at high levels can reduce the supply of oxygen to the heart and weaken heart contractions, thus lowering the volume of blood transported to various parts of the body. In Swale Borough, CO is not at levels that are cause for concern to health.

Benzene and 1,3-Butadiene: Both pollutants are at low levels within the Borough and are therefore of no cause for concern, but at high levels possible chronic health effects can occur including cancer, central nervous system disorders, liver and kidney damage, reproductive disorders and birth defects.

Lead: Lead (Pb) exhibits toxic effects in humans and can cause damage to the nervous system, kidneys, intestines, joints and reproductive system. However in Swale, Lead is not a cause for concern.

What about Ozone, so far this has not been mentioned?

There are two forms of Ozone (O3), O3 in the atmosphere forms what is known as the ozone layer, which is essential to limiting the level of UV irradiation reaching the earths surface. However O3 at ground level is not beneficial and can have a number of health effects. O3 is an acidic colourless gas. It is not emitted directly from any sources, but is a secondary pollutant formed by reactions between nitrogen dioxide (NO2), hydrocarbons and sunlight. The main source that causes ground level O3 to form is road traffic. O3 is an irritant to the lungs and can increase the onset of asthma and symptoms of other respiratory diseases. Since O3 can take several hours or even days to form and because it can be formed at considerable distances from its individual precursor pollutants, control and monitoring of O3 is on a regional or national scale.

Why have Air Quality Standards been set?

Air Quality Standards have been set under the National Air Quality Strategy with a view to ensuring an acceptable level of air quality for the public at large. This level should not pose significant risks to human health or quality of life and carry no unacceptable social or economic costs.

What is an Air Quality Management Area?

An Air Quality Management Area (AQMA) is a designated area where national guideline limits for air pollutants are being exceeded. The area can be just one or two streets or much larger. The AQMA will be the focus for action planning to improve air quality.

Is Swale Borough the only district to have AQMAs?

Swale is not the only Council to have an AQMA, over 200 local authorities have declared AQMAs within their district, in which the vast majority of these are for NO2.

Will an AQMA affect the value of my property?

Designation of AQMAs is a legislative requirement and not an optional process. Other councils have declared AQMAs and to the best of our knowledge there have been no reported effects on property values. However if you live within one of the AQMAs and wish to sell your property this information may be declared if an environmental search is carried out.

How will this authority treat planning applications for development inside the AQMAs?

It is not the intention of this authority that AQMA designation should prohibit development. However each application for development will be considered for its potential impact on air quality on a case-by-case basis. More weight will therefore be given to air quality considerations, where developments would have significant adverse impacts on air quality inside, or close to the AQMAs and where proposals for sensitive developments (i.e. residential) could be adversely affected by poor air quality inside the AQMAs.

I live in the AQMA - is air quality getting worse?

Overall air pollution from all sources, including road vehicles has declined over the past two decades. However for some roads within the AQMAs there has been an upward trend in results. Furthermore, air quality standards specified to protect human health have become more stringent, but some roadside sites still generate what are considered significant amounts of pollution.

What will Swale Borough Council do now to address air quality?

In terms of action, the Pollution Team has already extended its air quality-monitoring network for NOx diffusion tubes within the AQMAs to gain a clearer picture of the spatial extent of air pollution. This Council will now formulate an Action Plan with the aim to reduce pollution to levels below set targets, through proposals such as promoting reduced car usage, green transport etc. Many actions required to reduce pollution levels are beyond the direct control of this council and we will therefore liaise with relevant organisations such as Kent County Council and the Highways Authority to work towards achieving the necessary reductions. In conjunction, this council is conducting a Further Assessment to supplement information already collected and help focus measures in the Action Plan.

How long will this last?

The Action Plan will be drawn up over 18 months while the Further Assessment will be conducted over a period of 12 months from designation of the AQMAs. If exceedances still occur after measures to address air quality have been employed, this council will need to continue until it is certain that any future exceedances are unlikely. This could take a number of years. Even when levels fall below set targets and the AQMA can be revoked, this council will still need to ensure air quality issues maintain a high profile in the affected areas by meeting the requirements of the air quality strategy.

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