PM2.5 graphs for the last day or so in Eastbourne do not make for comfortable viewing. According to DEFRA, concentrations above 54ug/m³ are considered "high". As you can see from the graph below, levels have been peaking above that over the last 24 hours.

PM2.5 levels for 24 hours up to 2019-01-25 0700 GMT

This has brought the 24h average value up to above 40ug/m³ for the second time this week.

24 hour average value of atmospheric PM2.5 for the last 7 days

I am unclear on the causes of the sustained high level of pollution. What was notable yesterday evening though, was a distinct odour in the air, not obviously from the sewage works on this occasion. It smelled more like creosote, or perhaps some fumes resulting from burning plastic. The pollution was not localised either, sensors across Eastbourne were reporting raised PM2.5 levels, according to Luftdaten.