Authors Hao Wu, David Carslaw, Louisa Kramer
Compilation date 17 January 2022
Customer Dumfries and Galloway
Approved by David Hector
Copyright Ricardo Energy & Environment
EULA http://ee.ricardo.com/cms/eula/

Contract reference Report reference

This report has been produced for Dumfries and Galloway and examines the impact of lockdown measures on evolving ambient air quality data. This analysis focuses on NOx, NO2 (and ozone data where measured) from January 2020 through December 2021, and uses proven modelling techniques to discount the influence of weather on ambient pollutant concentrations. Details of this methodology can be found in this blog. At roadside locations NOx concentrations will be closely linked to primary emissions and should show the direct impact of reduced local traffic on air pollution. NO2 will be from a mixture of primary emissions and secondary chemical reactions but should again be closely linked to local traffic reduction.

With a reduction in NOx, we may expect to see an increase in ozone at roadside locations, as there will be limited freshly emitted NO available to scavenge ozone. Additionally, during the lockdown period, there were a number of regional ozone pollution episodes which may also have an effect on any changes observed. High ozone episodes typically occur during the summer season, when weather conditions are warm and sunny.

N.B. Both measured and modelled data reported here are provisional pending full QA/QC processes.

Time Series

First let’s look at the daily concentrations of the pollutants since January 2020 and get a general sense of the trend of pollutant concentrations. The dark green shading represents periods when lockdown was in place across most of Scotland. The light blue shading indicates the periods during which various restrictions on a more regional level have been implemented.

Dumfries

NO2

NOx

Eskdalemuir

NO2

NOx