We’ve been a little quiet on our quality project while we waited for the Wiltshire Council Purple Air sensors to come online across Chippenham.
Of particular interest is the PM2.5 particulates measured by the Wiltshire Council project.
Background
Our own air quality monitors have been running in Chippenham for over a year. Ours are battery operated devices and this has resulted in considerable maintenance. Now that Wiltshire Council Purple Air monitors are rolled out across Chippenham and Wiltshire we’ll use this post to look at the publicly available data over the past month. In order to easily do this the six hour averaging period has to be selected on the Purple Air map. Raw PM2.5 by PurpleAir
Langley Road Sensor
The Langley Road sensor is co-sited with our own sensor, positioned on a drainpipe approximately 7 metres from Langley Road. Langley Road is a busy road, though doesn’t often have traffic backed up as far as our sensor location outside of peak hours. It is also close to Wavin, the Cockleberry lane gas fired power station, and the Langley Park site and housing development.
In order to view 1 months worth of data we need to change the averaging window on the map to a 6 hour period. The measurements for September to October are shown in the image below.
Around October 2nd the Air quality across Chippenham was poor with PM2.5 particulates at 40ug/m3. Twice the UK government limit and eight times World Health Organisation recommended limits. So what caused this poor air quality?
Is this Chippenham only?
The purple sensor map gives the ability to look farther afield across the UK.
Looking at data from Tintern across the Severn estuary we see the same pattern with highs around the 2nd October. The pattern seems to be repeated across the Bristol, Bath, Chippenham, Calne, and Marlborough region. So it appears to be a regional phenomenon rather than a Chippenham one.
European Supercomputer Copernicus
Through the website Earth.nullschool.net we are able to access the Copernicus European Supercomputer data for the 2nd October with its prediction for PM2.5. (Very cool data – please explore this website and data – it’s fantastic!)
The forecast predictions for 2nd October showed 7ug/m3 maximum across the day, many times lower than our 40ug/m3. Though in the white areas the PM2.5 is higher at 15ug/m3. So if it wasn’t predicted to be so high – what caused it outside of supercomputer model predictions? Or is it hard to predict exactly what particulates are transferred?
If we look at the wind patterns it appears that pollution could be arriving from the South-West. Checking the Weymouth Purple Air sensor we see a similar pattern.
Storm Amy
The main meteorological phenomenon around this date was storm Amy. Storm Amy hits UK with heavy rain and strong winds – BBC News
So the most likely explanation is that Storm Amy transferred PM2.5 particulate pollution to the UK.
Please explore the data yourself and let us know if you have any insights?