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| Summary Monitoring Data Monitoring Data Continuous Monitoring Stations Diffusion Tube Monitoring Bias Adjustments To find monitoring locations use My Spelthorne, and navigate to My Maps and tick the Tube Locations to show these on the map. Summary Monitoring Data We have prepared summaries of the results of all monitoring in the Borough for 2007, 2008, 2009 and 2010, which provide an overview of air quality in each calendar year. Data presented in these summaries is bias adjusted. . Monitoring Data Results are available to download for all the continuous monitoring stations and diffusion tubes, as follows:
Continuous Monitoring Stations
Diffusion Tube Monitoring The Council has a network of 46 diffusion tubes. Diffusion tube monitoring has been ongoing in the Borough since 1995 - with just four locations being monitored at that time. This expanded to 11 locations by the summer of 1997 and to 26 locations by 2002. Tubes 27 to 42 were added in December 2003 to provide a better coverage of the Borough. In May 2004, tube 41 was moved from Knowle Green, Staines to Green Street, Sunbury.Tube 42 is a travel blank. This tube is taken with the exposure tubes to and from the exposure sites and is kept under refrigerated conditions throughout the duration of the exposure period. The results from this tube should be close to 0. Tubes 43, 44, 45 were added to the network in September 2007 and are triplicates at our continuous monitoring station in Sunbury. Tube 40 (a duplicate at Knowle Green, Staines) was removed in February 2008. Tubes 46 and 47 were added in February 2008 to improve coverage of the Borough. The Highways Agency had three tubes from its national NO2 diffusion tube network within Spelthorne. This survey finished in March 2011. Each of the chosen locations are on or near major roads and are positioned as close to residential properties as possible. The tube references are HA1, HA2, and HA3. Results were previously collated by financial year (April to March), but are now collated by calendar year (January to December). In 2010, an extra twenty nitrogen dioxide tube locations were added at Stanwell Moor, Stanwell and north Ashford as part of a one year survey of the Heathrow area with neighbouring Councils. The tube references for these locations are HSP1 to HSP20. There was insufficient data capture at the study colocation site and so the results have been bias adjusted against the National Bias Adjustment Factors spreadsheet for Gradko, 50% in acetone tubes, version 09/11. This gives a bias adjustment factor for this study of 1.03. A BTEX diffusion tube was also added at Long Lane, Stanwell in 2010 in response to the London Borough of Hounslow's 2009 Updating and Screening Assessment, that recommended further assessment of a fuel oil depot on the boundary between the two Councils. Bias adjustments
The bias adjustment factor is the method bias between diffusion tube monitoring and the results of a continuous monitor. In Spelthorne this is calculated from triplicate diffusion tubes located at the Oaks Road, Stanwell continuous monitoring station. In 2008 and 2009 a full year of results was also available from triplicate diffusion tubes located at the Council's continuous monitoring station at Sunbury Cross. However, the precision and accuracy of the tubes located at the Oaks Road site in both years was found to be better and so the bias adjustment factor was again calculated from that site only. In 2010 the bias ajustment factor used was again calculated from the Oaks Road site. Our bias adjustment calculation spreadsheets can be downloaded for 2008, 2009 and 2010. |
