Monitoring methods and reports

The Law
Where we monitor
Monitoring methods
Diffusion tubes
Automatic monitors
Air quality reports
Downloadable documents

The Law

The Environment Act 1995 places a duty upon Local Authorities to conduct a review and assessment of air quality in their areas. The Air Quality Regulations 2000 prescribed the following air quality objectives on which the review and assessments are to be based on:-

• Benzene
• 1,3 - butadiene
• Carbon monoxide
• Lead
• Nitrogen dioxide
• Ozone
• Particles (PM10)
• Sulphur Dioxide

Where we monitor

Since 1991, concentrations of three common gaseous pollutants have been monitored at the Deane House, Belvedere Road, Taunton. This site is representative of an urban background location, which is typical of a site where people are regularly present and might be exposed to air pollution over extended periods of time. Concentrations of ozone, nitrogen oxides and sulphur dioxide are continuously monitored to provide information on long-term trends of air quality.

The Council also has a Mobile Air Quality Unit (MAQU) that is used to obtain information on air quality at specific locations over fixed time periods, for approximately one year. The Unit is capable of continuously monitoring concentrations of nitrogen oxides and particulate matter (PM10), two of the most important pollutants emitted by road vehicles. Due to the length of time the unit must remain at a location and the specific criteria to be satisfied before locating it, the number of areas that can be monitored is limited. The results from the monitoring data collected by the mobile unit are used for detailed investigations specifically for the review and assessment process.

Monitoring methods

There are many different ways to monitor air quality, which vary widely in complexity and cost. It is essential to choose the most appropriate methods to meet our own requirements. The following methods are the ones used by the Environmental Protection Team.

Diffusion tubes

Diffusion tubes are a commonly used method for measuring concentrations of a range of pollutants. We, like many local authorities, use diffusion tubes for measuring nitrogen dioxide. They consist of a small plastic tube approximately 7 cm long and 1 cm in diameter. During sampling, one end is open and the other contains a gauze impregnated with a substance that is very good at absorbing nitrogen dioxide. The tubes are exposed for periods of one month and, at the end of the exposure period, the tube is sealed and returned to a laboratory for analysis.

This method of monitoring is very useful for getting information on concentrations over a wide area, as they are cheap enough to have lots of tubes distributed around the Borough. It's also easy to find suitable sites for the tubes as they can be attached to lampposts.

Automatic monitors

These are sophisticated electronic analysers, which continuously measure concentrations of different pollutants. There are different types of analysers for each pollutant. The data that they collect is stored in a data logger, which is then downloaded to a central computer where it is interrogated and analysed.

There are three analysers at the permanent monitoring station at The Deane House and two in our Mobile Air Quality Unit.

Air quality reports

Monitoring is in progress to help establish how the concentrations of nitrogen dioxide concentrations vary along the road network throughout the Borough. The boundaries of the AQMAs may well be extended should the results of this work indicate that levels are above the specified objective level.

Alongside this detailed investigation, the Council have produced an Air Quality Action Plan that sets out how it is proposed to make the necessary improvements in air quality within the AQMAs.

Downloadable documents

1st Stage Review and Assessment 1999 (Hard Copy Only)
2nd Stage Review and Assessment 2000 (Hard Copy Only)

All air quality documents are available to view on the downloadable forms and publications web page.