The temperature got down to a frosty -2°C, which is quite low for Eastbourne, especially this early in December. And as the temperature dropped so the reported particulate matter levels rose.
I was concerned at first that it might be a fault with the sensor, because the correlation was so strong. However, the wind was largely out of the south, my sensor was not the only one in Eastbourne reporting raised PM levels (indeed it was not even the highest reading when I checked), and the MetClim forecast has been for another Parisienne plume of pollution to be with us at this point in time.
So all is calm, all is right in sensorland tonight.