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Air quality - where I live


What's my nearest monitoring location?
What are levels now?
Monitoring in 2009 and 2010
What pollutants are monitored in the Borough?
How do we monitor?

        air quality

Monitoring locations

Interactive map

 Find your nearest monitoring point using
My Spelthorne (external website). Enter your
address and navigate to the 'My Nearest' tab
to find out more.

What are levels now?

To find out levels being recorded within the last few hours in the Borough visit the Heathrow air watch website (external website). This provides monitoring results for nitrogen dioxide and particulate matter levels at a continuous monitor located in Oaks Road, Stanwell. This independent website provides air quality information specifically for the Heathrow area. You can compare data from several locations around the airport as well as look at trends for the same location from 2001 to just a few hours ago.

To find out levels being recorded across the south east, the National Air Quality Archive has an online UK air pollution forecasting service (external website). Select the "south east" region and you will see the pollution forecast for the next 24 hours. This information can also be accessed from TV teletext page 155 or freephone 0800 556677 - available 24 hours a day.

Monitoring in 2010

  1. Five different air quality pollutants were monitored in the Borough in 2009: nitrogen dioxide; BTEX (Benzene, Toluene, Ethylene and Xylene); particulate matter (PM10 & PM2.5); sulphur dioxide; and ozone.
  2. Levels of these pollutants were monitored at three continuous monitoring stations and at a network of 69 diffusion tubes – find out more on how we monitor air quality.
  3. Hydrocarbon air pollutants were measured for the first time near the Esso Oil Terminal off Bedfont Lane, Stanwell.
  4. During 2010 twenty extra nitrogen dioxide diffusion tube locations were monitored in residential areas surrounding Heathrow airport as part of a one year survey funded by the Department of Environment, Food and Rural Affairs (Defra).
  5. The annual average nitrogen dioxide air quality objective was exceeded at 9 diffusion tube locations, all of which were in exceedance in 2009 and/ or 2008.
  6. The annual average nitrogen dioxide air quality objective of 40 ug/m3 was also exceeded in 2010 at the Council's Sunbury Cross Monitoring Station. There were no exceedances of the hourly mean objective at the site, though it may be exceeded at relevant locations nearer Sunbury Cross.
  7. In general concentrations of nitrogen dioxide monitored in 2010 were higher than those of 2009.
  8. Results of particulate matter monitoring over the past three years indicate a general trend of reducing concentrations of particulate matter (as PM10) as an annual average and in the number of days where the mean concentration was elevated above 50 ug/m3. Both measures were well below the national air quality objectives.

We have prepared summaried of air quality monitoring in Spelthorne for 2008 (Pdf 41kB), 2009 (Pdf 63kB) and 2010 (Pdf 1,060kB). Air quality can be a regional issue and in 2011 we will continue to work with neighbouring authorities in both monitoring and tackling air quality issues.


What pollutants are monitored in the Borough?

Nitrogen dioxide, benzene and particulate matter are monitored in the Borough. Nitrogen dioxide is the principal pollutant of concern in the Borough and the most extensively monitored. More information on these pollutants is available on the Air Quality and Health page.

There is currently only one continuous monitoring station, at Oaks Road, Stanwell, which monitors nitrogen dioxide and particulate matter. This station is owned by Heathrow Airport Ltd, operators of Heathrow Airport. A continuous monitoring station run by the Highways Agency at Junction 13 of the M25 motorway was closed in December 2010. This station also monitored ozone, carbon monoxide and sulphur dioxide concentrations. Particulate matter monitoring at Sunbury Cross ceased in January 2011. Monitoring of nitrogen dioxide concentrations at Sunbury Cross has been funded by the Council through to the end of 2011.  

We also have a network of 46 diffusion tubes measuring levels of nitrogen dioxide across the Borough. In 2010 there was a one year survey around the Heathrow area with twenty new locations. The study funded by the Highways Agency - with three diffusion tubes at residential properties close to motorways and major roads, was discontinued by them in March 2011. During 2010 and 2011 a BTEX (Benzne, Toluene, Ethylene and Xylene) diffusion tube has been located at a property on Long Lane, Stanwell.


How do we monitor?

There are two techniques used in this Borough:
  • Diffusion tubes
  • Continuous Monitoring Stations
Diffusion tubes are a simple and cost-effective method of monitoring. It is a plastic tube (about the size of a finger) which can be attached to a lamp post. Material within the tube is covered in a special coating. The tube is exposed to air at a chosen location over a period of a month. The coating absorbs nitrogen dioxide and so it is possible to find out an average level of nitrogen dioxide present at that location during that month. At the end of each month, the tubes are sealed and then sent off for analysis to an independent laboratory.

                                                   A diffusion tube on a lamp post

The results from each month are then used to work out an average level of nitrogen dioxide for a year. Results from diffusion tubes can only be compared to the annual mean objectives for the pollutants. They are not as accurate and precise as continuous monitors but give a good general indication of average pollutant levels.

Continuous monitor at Sunbury                        Monitoring Station at M25

A continuous monitoring station is an enclosure that contains one or more instruments to measure air quality continuously. They can vary greatly in size from a small cabinet right up to a walk in container depending on the number and type of instruments held there to measure air quality. The equipment is capable of measuring air quality continuously and results can be available in real time. Results can be averaged over short time periods such as 15 minutes, an hour or 24 hours.