UK Air Quality Strategy

In 1997, the UK became the first country in Europe to develop an air quality strategy. The Strategy sets out the air quality issues facing the UK, the targets that the Government has set, and policies put in place to attempt to achieve those targets.

Central to the Strategy are the National Air Quality Objectives. Covering eight different pollutants, these objectives include the tolerance level and the concentration, an averaging time over which the pollutant should be measured.

National Air Quality Objectives

One of the main components of the UK Air Quality Strategy is Local Air Quality Management (LAQM). Since 1997, all Councils (other than county councils) have been assessing the air quality in their area and, where a problem is found, developing action plans to address the situation.

Under LAQM, Councils must investigate the levels of pollution in their area. They do this in a number of ways. The most obvious is to measure concentrations of the main pollutants directly, using monitoring equipment. However, this equipment is often expensive and, in order to obtain good quality data, usually needs to stay in the same place for long periods of time. This means that monitors cannot give a complete picture of an area, and so mathematical computer models are used to predict what the air quality would be like in other areas, based on measurements and known sources of pollution, such as roads and industrial plant.

Models can also be used to help predict trends in pollution levels, and the effects of different weather conditions and source activity patterns (such as traffic levels, vehicle types, etc). In this way, air quality models can be used to assess whether or not the National Air Quality Objectives are likely to be breached in their target year. This process of monitoring, data collection and predictive modelling is known as "review and assessment".

If after carrying out review and assessment, a local authority finds that one or more of the National Air Quality Objectives is likely to be breached, it is obliged by law to declare an Air Quality Management Area.

Once an authority has declared an Air Quality Management Area, it must then develop an Action Plan, which sets out how it uses the powers at its disposal in pursuit of the National Air Quality Objectives. It is important to note that Councils are not actually obliged to achieve the objectives, as they do not have sufficient control over all of the sources that could potentially give rise to the breach. For example, major roads and motorways are usually under the control of the Highways Agency, and large industrial processes, including power stations, are regulated by the Environment Agency. Councils have no powers to direct either body, although the Environment Agency has given a commitment to assist where industry is the main cause of the breach. The great majority of Air Quality Management Areas have been declared because of emissions from road transport as is the case in Bournemouth.

The Main Sources of Air Pollution

These are the main pollutants and where they come from.

Particulate Matter (PM10)

The principal source of PM10 in European cities is road traffic emissions, particularly from diesel vehicles. It is also emitted from industrial combustion plants and public power generation, commercial and residential combustion, and some non-combustion processes (e.g. quarrying). Natural sources include volcanoes and dust storms, but these sources produce only a small percentage of fine particulate matter. Levels are highest in urban areas as it is a traffic-related pollutant.

Nitrogen Dioxide (NO2)

Nitric oxide (NO) is produced during high temperature burning of fuel (e.g. road vehicles, heaters and cookers). When this mixes with air, NO2 is formed. Levels are highest in urban areas as it is a traffic-related pollutant.

Ozone (O3)

Ground level ozone is a secondary pollutant; it is formed through a chemical reaction of volatile organic compounds and nitrogen dioxide in the presence of sunlight. As this process is dependent on sunlight, levels are higher in the summer. The reactions can take some time during which the polluted air has drifted many miles. The highest levels tend to be found in rural areas down wind of urban or industrial areas.

Sulphur Dioxide (SO2)

Fossil fuel combustion (principally power stations), conversion of wood pulp to paper, manufacture of sulphuric acid, smelting, incineration of refuse. The most common natural source is volcanoes.

Volatile Organic Compounds (VOCs)

Benzene
The main source of atmospheric benzene in Europe is combustion by petrol vehicles, which accounts for about 70% of emissions. Another 10% comes from the distillation, refining and evaporation of petrol from vehicles.
Other VOCs play a role in the photochemical formation of ozone in the atmosphere.

1,3-Butadiene

The main source of 1,3-Butadiene is also principally from road traffic, in the combustion process of petrol and diesel vehicles. Unlike benzene it is not a constituent of fuel but is produced through the combustion of olefins. An additional source is from industrial processes such as synthetic rubber manufacture.

Carbon Monoxide (CO)

CO forms where carbon fuels are burned, either in the presence of too little oxygen or at too high a temperature. One main source is idling vehicle engines and vehicle deceleration. Smaller amounts are released into the atmosphere from organic combustion in waste incineration and power station processes. Levels are highest in urban areas due to its close association with road traffic. However, in the UK levels are generally low, well below the targets set by the Government.

Lead (Pb)

As much of the airborne emission of lead originates from road traffic, concentrations are decreasing with most cars running on unleaded and lead replacement petrol. Other sources of lead pollutants include waste incineration and metal processing. The largest industrial use is manufacturing batteries.

Toxic Organic Micro-Pollutants (TOMPs)

PAHs (Polycyclic Aromatic Hydrocarbons), PCBs (Polychlorinated Biphenyls), Dioxins, Furans
Produced by the incomplete combustion of fuels, road transport and industrial plant are the largest source. Open burning is a major source in the UK and comparatively large amounts are released on and around bonfire night. Tobacco smoke is also a source.

More information can be  found in Uk Air Quality Strategy

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