Ambient Air Quality

Air quality is an issue of concern for all of us. Healthy people do not normally notice any effects from air pollution, except occasionally when levels increase due to weather or traffic conditions. If so some people may get eye irritation and start to cough with breathing becoming uncomfortable. As most air pollutants are invisible the long term effects are often not appreciated but it remains a significant mortality burden within the UK.


The effects of poor air quality on health increase gradually as pollution levels rise. However for those with lung or heart conditions such as bronchitis or emphysema the effects of poor air quality can be serious. Daily changes in air quality trigger increased admissions to hospital and contribute to the premature death of those who are seriously ill.

It is estimated that the mortality burden from particulate exposure alone in the UK in  2008 was equivalent to 29,000 deaths with an associated loss to the population of 340,000 life years (COMEAP 2010).  Public Health England have released data estimating local mortality burdens associated with particulate air pollution at a local authority level. A copy can be downloaded at the bottom of this page.

More information on the health effects of poor air quality can be found on the following web sites:

World Health Organisation (WHO)

Public Health England

Committee on the Medical Effects of Air Pollutants (COMEAP)

UK GOV Website


Types of Pollutants 

  • Benzene is a hydrocarbon that comes almost entirely from vehicle exhausts.
  • 1,3-Butadiene also comes almost exclusively from vehicle exhausts.
  • Carbon monoxide is the product of incomplete combustion of fossil fuels.
  • Lead was used as a petrol additive, however with the phasing out of this fuel in 2000, ambient concentrations have now dropped significantly.
  • Nitrogen dioxide is formed whenever fossil fuels are burnt in air. The main source in Winchester is from motor vehicle exhausts.
  • Ozone in the upper atmosphere is essential to protect the earth from harmful ultraviolet light. However at high levels near the ground this gas can irritate the airways of the lungs. It is formed as a secondary pollutant i.e. by the reaction of other pollutants with each other.
  • Sulphur dioxide is mainly produced during the burning of coal and oil.
  • Particles or PM10 are small airborne particles that can penetrate deep into the lung. They come from many sources including sea salt, wind blown soil, combustion processes and droplet formation in the atmosphere. However, with Winchester town centre the main primary source is from combustion processes and especially diesel engines.
  • Fine particulate matter or PM2.5 or PM1.0 are the even finer fractions.  There has been a recent move towards these parameters as better representing health related issues than PM10. However under current UK law there is no requirement to assess these parameters at a local level.

Further information on these pollutants can be found in the National Air Quality Strategy that can be downloaded from the DEFRA website

Monitoring in Winchester

We have two real time air quality monitoring stations in Winchester town centre. These consist of a background site at Lawn Street near Friarsgate (Nitrogen dioxide) and a roadside site in St Georges Street (Nitrogen dioxide and Particles). We also have over forty nitrogen dioxide diffusion tubes monitoring air quality across both the town centre and the district. Results from all our monitoring is available upon request and annual summaries can be downloaded from the link at the bottom of this page. Information on air quality at a national level can be downloaded from the DEFRA UK AIR Website. This includes a prediction for air quality over the next 24 hours. Annual summaries of the air quality monitoring results can be downloaded at the bottom of this page.

All Winchester's air quality data is also now hosted live on UK Air Quality net and historic data from 2011 onwards can also be viewed. Please note recent data has not been ratified or scaled so is subject to change. 

Air Quality in Winchester Town Centre

Since the implementation of Part IV of the Environment Act 1995 all local authorities have been under a duty to review air quality within their district. The current objectives that have to be met are prescribed under the Air Quality (England) Regulations 2010 . It is a requirement that each local authority conducts a formal staged review of air quality within its district in accordance with a comprehensive set of guidance documents. These reports are then sent to the Department of Environment, Food and Rural Affairs (DEFRA) for approval. All these reports can be downloaded at the bottom of this page. Where compliance with such objectives is unlikely then the local authority has to declare an Air Quality Management Area (AQMA). Further information on this procedure, including all the guidance documents, can be found on the DEFRA air quality web page.

Having completed these assessment an AQMA was declared in November 2003 for Winchester Town Centre for both the nitrogen dioxide annual mean and the particles 24 hour mean air quality objectives. To download a map of the AQMA see the documents menu at the bottom of this page. An Informal Member/Officer Working Group met regularly between 2004 to 2006 and reviewed and prioritised all possible actions in accordance with comprehensive guidance documents issued by DEFRA. It produced a draft Air Quality Action Plan (AQAP) in December 2004. Following a comprehensive consultation exercise it then produced a revised final draft version of the AQAP that was sent to DEFRA for comment.

The final version of this action plan was published in 2006 following feedback from DEFRA on the final draft. This version ensured compatibility with Hampshire County Council's Local Transport Policy for 2006 to 2011 which has now been replaced with the 2011 to 2031 version (often called LTP3). The AQAP is a large document so has been split into Chapters for downloading at the bottom of this page.

Many of these actions required delivery by other organisations, the most important of these being Hampshire County Council, who as the local Highway Authority supported the plan. The two key Hampshire documents that now need to be read in conjunction with our AQAP are now the Local Transport Plan 2011 to 2031 and the Winchester Town Access Plan. Both these documents were finalised in 2010 and are not therefore not specifically referenced within our current AQAP.

An independent review (Progress Report) was conducted in 2010 to assess progress made in implementing the AQAP, this report can be downloaded from the bottom of this page. An Informal Scrutiny Group (ISG) reviewed the AQAP throughout 2011 and its recommendations were adopted by the Council in 2012.