I recently had a useful meeting at the council to try to find out more about the way in which our air quality is monitored in East Cambridgeshire. The presence of particulates and other pollutants in our air is something that has caused some residents concern, particularly in view of the large numbers of heavy vehicles thundering through our village every day.
The council is obliged under the Environment Act 1995 to assess and report local air quality, including assessment of a range of pollutants including nitrogen dioxide (NO2) and particulates.
Measuring nitrogen dioxide
Measurement of nitrogen dioxide is mostly done using small tube monitors fixed to lamp posts at a range of locations in the district. The tubes most relevant to Sutton are at the junction with Tramar Drive and at the A142 at Witcham Toll. These monitors measure NO2 over a period of time.
Continuous monitors give a more accurate measure of NO2 in the atmosphere. There is only one continuous monitor in East Cambridgeshire, which is hired from another council, and costs £5,800 a year to run. This monitor gives readings as 15 minute mean averages. Originally partially funded by Sainsbury’s, this monitor is now funded by the County Council under its Local Transport Plan. King’s College London undertakes the data management for the monitor, which involves checking the data for anomalies and removing them.
There is only one piece of equipment in East Cambridgeshire to measure particulates, located at Wicken Fen; it measures PM10 (larger concentrations of particulates), and is hired from Fenland District Council. It is resource-intensive to run, and is situated alongside DEFRA equipment in their station there. It is not yet online, but replaces one that was previously located there. Its rural location provides some idea of the ‘baseline’ level of particulates in the district – that is, what the air would normally be expected to be like well away from traffic and other sources of pollution.
This PM10 monitor, known as a ‘Met One BAM’, uses low-level radiation to measure particulates. More equipment to measure PM10 would be comparatively cheap to purchase but would cost in the region of £1,600 a year to run, and would need to be housed somewhere.
Equipment for measuring PM2.5 (the smaller and more dangerous concentrations of particulates) is much more expensive to buy – potentially £20,000 or more – and in any case there is as yet no clear guidance on what items of equipment and methodologies are acceptable to DEFRA as reliable ways of measuring PM2.5.
If villages like Sutton are to build a conclusive argument for a lorry ban, we need a lot more testing – the 24 hour ‘safe limit’ for PM10 must be exceeded on at least 30 occasions in a year for a breach of the limit to be said to have occurred. That means a lot of testing – and without permanent PM10 monitors, and the budget to run them, gathering that body of evidence is difficult. That’s something the Joint HCV Group of local villages, which includes Sutton, is currently grappling with.