Oxford Friends of the Earth have distributed small PurpleAir particulate monitors across the city and are using them to identify particular hot spots. Realtime data from the monitors is displayed on an online map (see below). The monitors capture data continuously so are able, for instance, to detect evening peaks on cold, still days. They will help us to get idea of where and when particulate pollution is worst in Oxford.
We chose PurpleAir monitors because recent research comparing 44 small-scale sensors found PurpleAir (PA-II) data had the highest comparability with the expensive official air quality monitors typically used by City Councils.
Two of the new monitors are co-located for calibration with the Oxford City Council’s monitoring station in St Ebbes (the only station in Oxford that measures PM2.5 emissions). Initial data suggest that the PurpleAir monitors closely track the Council’s official monitor (after simple adjustments for differences in the method of measuring particulates).
We are still collecting and analysing data from across Oxford, but initial indications are that Oxford’s particulate levels are primarily driven by domestic combustion, not traffic. Initial data also suggest that Oxford’s winter particulate levels can be very high. For example, on 14 Jan 2022, when Londoners (but not Oxford residents) were warned to stay indoors because of high particulate levels, Oxford’s levels were comparable to London’s.