The level of PM2.5 (and PM10) showed two distinct peaks during the night of 4th June. I’ve pulled out the magnitude and time of the peak from all our devices and put them in spreadsheet which I will attach here (when I figure out how). The spreadsheet can be sorted in a few ways and this makes it easy to look at the location and timing of the peaks. The intention is to see if there is a consistent timing pattern that would support the theory that the increased levels arrived on the wind (SW that night).
Although the limited data is not conclusive it does support the theory - Hessle is the first to show the peaks, then Cottingham and Kingswood almost at the same time. Then Longhill and finally Brandesburton.
The Willerby device is a bit unusual - it only showed one peak and that seemed to be an hour later than the others would suggest. Maybe some odd air flow patterns around Willerby?