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Local variations in particulate levels

Oxford Friends of the Earth is a thriving and effective local group that has been active for over 40 years. Our purpose is to work together to promote a healthy and sustainable environment

Given the high cost of the official monitor, including its running cost, it is obviously not feasible to site a number of them around Oxford to obtain a more local view of air pollution. 

This is where our network of PurpleAir monitors is so useful. Having shown the relevance of information on particulate pollution they produce, we can now see that there are substantial differences between air pollution levels at St. Ebbe’s and elsewhere in Oxford. 

We can measure these differences between readings from PA monitors at St. Ebbe’s and elsewhere. These graphs illustrate:

The differences in measurement of particulates between St. Ebbe’s and other Oxford locations. (The measure is an index measuring particulates from the Purple Air real time graph.)
  • The three panels of the above graphs show, for three different areas in Oxford, the differences in readings compared to the average of the St. Ebbe’s PurpleAir monitors.
  • The readings are different across Oxford showing spatial variation.
  • At these six locations, daily pollution levels are almost always higher than at St. Ebbe’s, and at times, substantially higher (even when, as here, we average over a whole day, which tends to miss evening burning peaks). This is especially so on the coldest days!
  • For example, in North Oxford (at Kingston Road and Complins Close) it seems that smoke from stationary house-boats is often a problem, especially in cold spells, while Chalfont Road (not shown here) appears to be another local smoke hotspot, very likely from several domestic burners. It is plausible that at the St. Ebbe’s school site, the monitors are more distant from local domestic combustion and from house-boats, and this is why they tend to indicate lower levels of particulate emissions than other parts of Oxford.  

The graph below shows PurpleAir readings for one location—Complins Close—alongside those for St. Ebbe’s. This confirms that particulates pollution at Complins Close is regularly substantially higher that at St. Ebbe’s.

Comparison of PurpleAir readings for Complins Close and St. Ebbe’s. (Daily data. The measure is an index measuring particulates from the Purple Air real time graph.)
  • This graph shows the St. Ebbe’s PurpleAir monitor and the monitor placed at Complins Close in Summertown, which experiences pollution highs from local burning.
  • The Complins Close monitor exceeds the St. Ebbe’s monitor on most days.
  • There is a strong connection between peaks in PM2.5 particulate emissions and cold temperatures—suggesting the link with domestic combustion.