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Air Quality Monitoring in the Parishes of Haresfield, Hardwicke and Standish in Gloucestershire.
Gloucestershire County Council (GCC), as waste disposal authority, has contracted Urbaser Balfour Beatty (UBB) to build and operate a waste incinerator at Javelin Park, Haresfield, GL10 3ET.
In line with industry good practice, a Community Liaison Group (CLG) has been set up between UBB and the Parishes surrounding the incinerator site in order to facilitate good relations and communications with the neighbouring communities. Details of the remit, make-up, and meeting minutes of the CLG can be found at https://www.ubbgloucestershire.co.uk/community-liaison-group/
UBB agreed early on to provide a measure of funding for local community projects in the surrounding Parishes represented at the CLG, and one of the early requests from all of the Parishes was for Environment Agency (EA) approved air pollution monitoring equipment in the field in order to reassure the local communities. UBB kindly agreed to provide £29k for this purpose, to run for a 31/2 year period: 6 months prior to incinerator start-up to set a baseline, and 3 years of operation.
Air Monitoring Setup
The pollutants measured are Nitrogen Dioxide (NO2), by means of diffusion tubes, and particulates using laser nephelometers.
Seven monitoring sites were agreed, and two of the sites, Haresfield and Hardwicke Village Halls, were selected for particulate measurement, and the devices chosen were the Turnkey Osiris which have EA MCERTS approval. They are mounted in weatherproof housings in turn enclosed within vandal- resistant steel cages mounted on the external walls at ground level. Wind vanes are mounted at roof level.
Position of monitoring sites
Handling of Data
Air Quality Limits
The UK national and EU air quality limits and objectives are set out in detail by DEFRA at https://uk-air.defra.gov.uk/air-pollution/uk-eu-limits , however for our purposes the limits of interest are:
· 40µg/m3 for continuous NO2 and 200µg/m3 one hour max exceedance no more that 18 times per annum
· 40µg/m3 for continuous PM10 and 50µg/m3 max 24 hour mean no more than 35 times per annum
· 25µg/m3 for continuous PM2.5 (note this is currently an EU objective and a UK limit value by 2020. There are currently no short term exceedance limits).
It is important to realise that these are ambient limits which are the sum of pollution from all sources at the point of measurement. Attempting to identify the pollution from different sources is a highly complex scientific task which is currently the subject of research and no methods are yet available for routine measurements. So separating out pollution fractions from, say, vehicles, trains or industrial processes is currently impractical.
Data Accuracy
Low, diffuse levels of air pollution are inherently difficult to measure accurately, even with expensive equipment. With the modestly priced and relatively simple equipment we have chosen, do not expect absolute accuracy better than perhaps ± 30%, although relative, reading-to-reading results will be good. Think of the absolute results as indicating "low", i.e. well below the statutory limits and hence not a problem such as say 7.5µg/m3 , "medium" being in the area of the statutory limit such as 35µg/m3 so beginning to attract a measure of concern, and "high" such as 100µg/m3 + and attracting a real health concern if maintained. Diffusion tubes generally give a monthly average reading so cannot detect short term variations and peaks, whereas laser nephelometers can read as frequently as every minute so can detect short term events, although they are usually set to take readings somewhat less frequently.
Diffusion tubes have to be sent to an appropriate laboratory for analysis and are subject to an annual correction factor from the laboratory. We will be publishing the immediate results but subject to the previous year's correction factor, so absolute accuracy could be ± 50% but still adequate for low - medium - high assessment, and with good accuracy in terms of reading to reading variation. Annual data sets will be corrected when the annual factor is issued. The laser nephelometers take readings every 15 minutes, and data is downloaded generally on a monthly basis although equipment failures and Covid 19 impacts have caused some loss of data.
Data Dissemination
All recorded data will be displayed on this website together with indication of the statutory limits involved and any explanatory comments. Any questions should be directed to the local Parish Clerks in Haresfield, Hardwicke, Standish, Eastington, Moreton Valence and Frampton upon Severn. This website compiled by Chris Harmer for the CLG.
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