Thread by @johnwenger9

Significant drop in #AirPollution levels measured at the Cork #AirQuality monitoring site on @UCC campus due to #COVIDー19 related travel restrictions.
Follow thread for details.
Measurements by @CRAClabUCC and @EPAAirQuality.
Data analysis by Niall O'Sullivan.
#COVID19ireland

First measures introduced on 12 March had no major impact on air pollution. But more severe travel restrictions from 28 March have led to reductions of 47% in average NO2 concentration and 32% for PM2.5 compared to previous years.

NO2 data is very consistent - check out the average diurnal profiles for Quarter 1 (Jan-Mar) in 2018, 2019 and 2020. Remarkably similar! Morning peak due to vehicle emissions, evening peak due to combination of vehicles and solid fuel burning

Now look at average NO2 for 1-14 April. 2018 and 2019 show the large morning peak, but the evening peak is much smaller than in Jan-Mar (less solid fuel burning). The profile for 2020 shows greatly reduced levels, with only a small traffic peak in the morning.

Average diurnal profiles for PM2.5 during Quarter 1 (Jan-Mar) in 2018, 2019 and 2020 are again remarkably similar! The large evening peak clearly shows that domestic solid fuel burning is by far the dominant source of particulate pollution in Cork city.

Average diurnal profiles for PM2.5 from 1-14 April show a much weaker evening peak than during Jan-Mar. Overall lower PM2.5 levels in 2020, but since there are multiple sources of PM, will need further analysis. Evening peak in 2020 indicates solid fuel burning is still going on.

These results are consistent with those recently reported by @EPAAirQuality @EPAIreland, where NO2 levels were reduced by up to 50% at various sites across the country.

epa.ie/newsandevents/…

We recognise that this is a simple, straightforward analysis of the data collected at one monitoring location in Ireland. But we do think that the data is representative and also instructive in highlighting #AirPollution sources and the impact of #COVIDー19 travel restrictions.

A much more sophisticated analysis of #airquality data in UK has been conducted by @DavidCarslaw and reported in @airqualitynews here:
airqualitynews.com/2020/03/31/ric…

A detailed analysis of the impact of #COVIDー19 travel restrictions on #AirQuality in Switzerland has been conducted by @Empa_CH and is reported here: empa-interim.github.io/empa.interim/s…

@RicardoAirQ