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Air and Water

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Key trends: 

  • Air quality in England as a whole has improved significantly since 1990;

  • Nitrogen dioxide levels have been found to be too high in some towns; fine particulate matter is also a problem in some areas; 

  • Road traffic is the major source of atmospheric emissions;

  • Wiltshire Council has declared eight Air Quality Management Areas (AQMAs); Swindon Borough Council has not declared any AQMAs;

  • National estimates of pollutant emissions show the impact of major industry; this can clearly be seen in relation to the decrease in emissions following the closure of the cement works near Westbury and the temporary closure of the Honda factory in South Marston in 2009.

Wiltshire Council web pages on air quality:
http://www.wiltshire.gov.uk/communityandliving/publicprotection/pollutionandnoise/airandwaterpollution/airquality.htm

Swindon Borough Council web pages on air quality:
http://www.swindon.gov.uk/ep/ep-environmentalprotection/Pages/ep-environmentalprotection-airpollution.aspx

Defra pages on air quality: http://www.defra.gov.uk/environment/quality/air/air-quality/

Wiltshire Council Environmental permits register: http://www.wiltshire.gov.uk/communityandliving/publicprotection/pollutionandnoise/pollutionpreventionandcontrolppc/envpermitspublicregister.htm

Environment Agency Public Register search: http://epr.environment-agency.gov.uk/ePRInternet/SearchRegisters.aspx - search for 'Environmental Permits (Industrial installations)' by 'Local Authority' and enter 'Wiltshire' or 'Swindon'.

UK-Air Information Resource: http://uk-air.defra.gov.uk/

National Atmospheric Emissions Inventory: http://naei.defra.gov.uk/index.php

UK air quality objectives have been set for seven identified pollutants. In any area where the level of these pollutants exceeds the objectives, the local authority must declare an Air Quality Management Area (AQMA) and prepare an Air Quality Action Plan. An AQMA typically covers part of a town or city. This section shows the current AQMAs in Wiltshire and Swindon and the reasons for their implementation.

Swindon Borough Council currently has no AQMAs. Its latest Air Quality Progress Report is dated November 2011 and concludes that detailed assessment is needed at Kingshill Road and Devizes Road in Swindon, and in Stratton St Margaret.

There are eight AQMAs in Wiltshire, which have been declared because the annual mean objective for nitrogen dioxide has been exceeded. The AQMAs (and the year of declaration) are:

  • Westbury, centred on Haynes Road and Warminster Road (2001).

  • Bradford on Avon town centre (also declared for exceedence of the annual average PM10) (2001).

  • Devizes Amended (to include the town centre and London Road (2012).

  • Marlborough, centred on Herd Street and Barn Street (2011).

  • Salisbury city centre, within the Churchill Way ring road (2003).

  • Wilton Road, Salisbury, between the Old Manor Hospital site and St Paul’s roundabout (2007).

  • London Road, Salisbury, between the allotment railway tunnel and St Mark’s roundabout (2007).

  • Calne, centred around exceedences in New Road and Curzon Street (2013).

Maps showing the exact areas covered by the AQMAs can be found on Wiltshire Council's website (see link below).

Wiltshire Council publishes Air Quality Reports every year, subject to approval by DEFRA. They show that the main sources of pollutants of concern are road vehicles. At present, air quality is monitored for nitrogen dioxide (NO2) and particulate matter (PM10) at a number of locations across Wiltshire. Screening assessments have not identified any issues for other pollutants and so these are not currently monitored.

Wiltshire Council Air Quality pages include the Wiltshire Air Quality Strategy, Draft Air Quality Supplementary Planning Guidance, Community involvement, air quality statutory reports and pollutant information: http://www.wiltshire.gov.uk/communityandliving/publicprotection/pollutionandnoise/airandwaterpollution/airquality.htm

Swindon Borough Council web pages on air quality: http://www.swindon.gov.uk/ep/ep-environmentalprotection/Pages/ep-environmentalprotection-airpollution.aspx

The term nitrogen oxides (NOx) refers to the pollutants NO and NO2. These are primary pollutants, formed from high temperature combustion, such as in road transport and coal-fired power stations. Nitrogen oxides have been shown to increase acid rain, and counter-intuitively both leads to depletion of the stratospheric ozone layer and increases surface level ozone.

NO2 is the main pollutant of concern in Wiltshire, leading to the declaration of seven Air Quality Management Areas (see tab above). Swindon Borough Council has also found areas of concern and is assessing these in more detail.

There was a sharp decrease in NOx emissions in both Wiltshire and Swindon between 2008 and 2009. In Wiltshire, around half of the decrease can be attributed to the closure of the Lafarge cement works near Westbury in 2009. In Swindon, it can partly be attributed to the temporary closure of the Honda car manufacturing site in South Marston in 2009 following the earthquake and tsunami in Japan (300 tonnes less emitted from this site in 2009 than in 2008). Emissions in Swindon are therefore likely to have increased again in 2010 as the site returned to full production.

NOX emissions in England have declined by 61% in the past two decades, from 2132 kilotonnes in 1990 to 831 kilotonnes in 2009. There are no set objectives for total annual emissions of NOX.

The main sources of emissions in England in 2009 were road transport (36%), energy industries (26%) and industrial combustion (19%).

Note on data: there is a known 10% uncertainty either way for these figures.

Statistics: © Crown Copyright

Source: Air Quality Pollutant Inventories for England, Scotland, Wales and Northern Ireland: 1990 – 2009, A report of the National Atmospheric Emissions Inventory, AEA Group, and other data from the National Atmospheric Emission Inventory Data Warehouse: http://naei.defra.gov.uk/index.php

Sulphur dioxide (SO2) is a primary pollutant, formed through the combustion of fossil fuels, particularly coal and petroleum. High levels of SO2 can lead to the production of acid rain through being converted to H2SO4 in precipitation (e.g. rain, snow, hail).

While emissions in England as a whole decreased somewhat from 2008 to 2009, emissions in both Wiltshire and Swindon decreased sharply. In Wiltshire, this can largely be attributed to the closure of the Lafarge cement works near Westbury in 2009. In Swindon, it appears to relate to the temporary closure of the Honda car manufacturing site in South Marston in 2009 following the earthquake and tsunami in Japan. Emissions in Swindon are therefore likely to have increased again in 2010 as the site returned to full production.

SO2 emissions in England have declined by 91% in the past two decades, from 3103 kilotonnes in 1990 to 284 kilotonnes in 2009. There are no set objectives for total annual emissions of SO2.

The main sources of SO2 emissions in England in 2009 were power generation (38%), industrial combustion (23%) and refineries (14%).

Note on data: there is a known uncertainty of 4% either way for these figures.

Statistics: © Crown Copyright

Source: Air Quality Pollutant Inventories for England, Scotland, Wales and Northern Ireland: 1990 – 2009, A report of the National Atmospheric Emissions Inventory, AEA Group, and other data from the National Atmospheric Emission Inventory Data Warehouse: http://naei.defra.gov.uk/index.php

Particulate matter describes particles of solid or liquid suspended in air. The primary pollutant is particles which measure 10 micrometers or less in diameter, or PM10­.

Particulate matter has been linked to many adverse health effects, such as heart disease, lung cancer and a range of other respiratory conditions. PM10­ can inhibit photosynthesis in plants, and in large concentrations can influence the climate.

While emissions in Wiltshire and in England as a whole decreased somewhat from 2008 to 2009, emissions in Swindon decreased sharply. In Swindon, it appears to relate to the temporary closure of the Honda car manufacturing site in South Marston in 2009 following the earthquake and tsunami in Japan. Emissions in Swindon are therefore likely to have increased again in 2010 as the site returned to full production.

PM10­ emissions in England have declined by 57% in the past two decades, from 213 kilotonnes in 1990 to 90.9 kilotonnes in 2009. However, there is a known uncertainty of -20% to +30% on these figures.

There are no set objectives for total annual emissions of PM10­.

While Swindon has a significantly higher average rate of emission per square kilometre than England, this is to be expected.

The sources of PM10­ in England in 2009 are widespread, but include transport (26%) and commercial and residential combustion (18%), largely from burning coal and solid fuels. A reduction in coal use is a major factor in reduced PM10­ emissions since 1970.

Statistics: © Crown Copyright

Source: Air Quality Pollutant Inventories for England, Scotland, Wales and Northern Ireland: 1990 – 2009, A report of the National Atmospheric Emissions Inventory, AEA Group, and other data from the National Atmospheric Emission Inventory Data Warehouse: http://naei.defra.gov.uk/index.php

Fresh water for public supplies in Wiltshire and Swindon is removed (or abstracted) from surface water (such as rivers and lakes) and groundwater. Water resources are managed by the Environment Agency according to river catchment areas. Four main catchments fall within Wiltshire and Swindon: the Bristol Avon, Hampshire Avon, Kennet and Pang, and Vale of the White Horse.

The Environment Agency has produced a Catchment Abstraction Management Strategy (CAMS) for each of these. River systems have been assessed in terms of the amount of water available for abstraction. Each CAMS looks at the amount of water removed and aims to manage this to ensure there is enough water both for people and for a healthy natural environment.

Click here for link to the CAMS for the Bristol Avon and Hampshire Avon and the Kennet and Pang and Vale of the White Horse

The majority of Wiltshire’s rivers are over abstracted, with over 70% under threat if abstraction licenses already granted were used to their full extent. The rivers within the Bristol Avon catchment are the exception to this, but even within this catchment there is no more water available for further licensing.

66% of Wiltshire’s groundwater sources have been assessed as ‘poor’ in terms of quantity status, with the remaining 34% assessed as ‘good’.

Source: Environment Agency

Current flood risk zone maps for each of Wiltshire's Community Areas are available in the Maps section of this website.

Further information and Strategic Flood Risk Assessments is available here.

The overall quality of surface water (e.g. rivers, canals and lakes) is measured by assessing chemical and biological factors, including checking fragile indicator species and measuring the levels of nitrates and phosphates. Objectives for protecting and enhancing the water environment have been set by the Environment Agency under the European Water Framework Directive (WFD).

The ecological status of surface water bodies in Wiltshire and Swindon has been assessed at identified monitoring points and objectives have been set for each of these. They are grouped into areas called River Basin Districts (RBDs) and each RBD has a management plan. All water bodies in Swindon fall within the Thames RBD. In Wiltshire, they fall within two main RBDs – Severn and South West – with some in the South East and Thames RBDs.

The management plans and the details of the status and objectives for each individual water body can be viewed on the Environment Agency’s website (see section on ‘Supporting information’ under any RBD page to access the spreadsheet): http://www.environment-agency.gov.uk/research/planning/33106.aspx 

The ecological status of all surface water bodies in Wiltshire and Swindon in 2011 are shown in the attached table as a percentage of the total length, compared to figures for the Severn, South West and Thames RBDs.  The annual data from 2009 to 2012 for Wiltshire and Swindon is shown in the tables below.

The monitoring points for water bodies in each Community Area and their 2012 ecological status are available in the 'Water Data by Community Area' tab below and further analysis by Community Area is available on the Wiltshire JSA website.  

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Ecological Status of Water Bodies (% of total length)
Ecological Status of Water Bodies (% of total length)
[ Zoom ]
Ecological Status of Wiltshire's Rivers 2009-2012
Ecological Status of Wiltshire's Rivers 2009-2012
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Ecological Status of Swindon Borough's Rivers 2009-2012
Ecological Status of Swindon Borough's Rivers 2009-2012

A small number of water bodies in Wiltshire have been classed as having ‘bad’ ecological status: 

  • Biss Brook in Westbury Community Area has improved from 'bad' in 2009 and 2010 to 'moderate' in 2011; 

  • part of the River Marden in Calne Community Area has improved from 'bad' to 'poor';

  • Ampney and Poulton Brooks in Royal Wootton Bassett and Cricklade Area has remained in 'bad' status from 2009 to 2012;

  • Chitterne Brook in Warminster Community Area has deteriorated from 'good' in 2009 to 'bad' in 2012;

  • Willow Brook in Calne Community Area has deteriorated from 'moderate' in 2009 to 'bad' in 2012.

Wiltshire has one section (10.5km in length) of river which has been classed as ‘fail’ on chemical status: the River Marden southeast of Calne (10.5km). Very few water bodies have been classed at all in this category. Midford Brook on the Wiltshire border south of Bath (3.5km) was previously classed as 'fail' but in 2012 was classed as 'good' chemical status.

Source: Environment Agency

Groundwater is the water contained in underground sources. The quality of these has been assessed by the Environment Agency under the European Water Framework Directive, based on quantity of water and chemical makeup.

Groundwater supplies are extremely important. Their quality and quantity thus directly affects water supplies across the county. They are the foundation on which most surface water in Wiltshire relies, and are a good indication of the health of our hydrology. The table shows the status of groundwater bodies in Wiltshire.  

These figures are based on data for seven groundwater bodies in Wiltshire identified by the Environment Agency. The quality of most of this data is designated as being ‘uncertain’, with the exception of the ‘fail’ status on chemical quality for three waterbodies. This uncertainty must be kept in mind, but the data does provide a useful rough idea of the status of groundwater reserves in the county.

Source: Environment Agency Water Framework Directive data, November 2010

This section provides data relating to the ecological status of rivers in each Community Area. This is based on the location of the Environment Agency's monitoring points; there are no monitoring points in Mere or Salisbury Community Areas.

In order to get a fuller picture of the ecological status of whole rivers and their catchments, please use the introductory page map to identify other relevant Community Areas and select all relevant Community Areas in the Ecological Status of Rivers Section.

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