The environmental effects of lockdown
February, likely due to the cold weather meaning more road transport and increased use of central heating systems. In 2019 the average NO and NO x levels (calculated from daily mean data) over the January to July period were 3 µg/m³ and 13 µg/m³ respectively, the NOX concentration being well below the yearly average regulation of 40 µg/m³ (WHO, 2005). 2020 levels were reduced with averages for NO and NO 2 calculated as 2 µg/m³ and 9 µg/m³. Lockdown measures introduced by the UK government have a had a direct impact on road transport with all motor vehicle traffic decreased by 2.1% when comparing March 2019 to March 2020, with 1.8% of 2.1% directly caused by the coronavirus (COVID-19) pandemic lockdown. 13 As road traffic accounted for roughly 31% of anthropogenically produced NO x emission within the UK in 2018 (DEFRA, 2020), this would explain the reduced levels of NO x emissions recorded in Bournemouth throughout 2020. The graphs also show that maximum concentrations for both nitrogen oxides were much smaller in 2020 than in 2019. Therefore, it is clear concentrations of NO x gas emission have decreased in 2020. Also, despite the increased traffic to the area of Bournemouth on the 25th June 2020, caused by thousands gathering on the beach at Bournemouth and other nearby tourist locations (BBC South, 2020), there was no spike in NO x emissions in the area. 2.3 The relationship between Ozone and temperature Throughout the data for both 2019 and 2020 so far it has been clear that ozone concentrations are highest in summer months. Tropospheric O 3 production involves many photochemical reactions ((1), (13), (19) and (20)) that require electromagnetic radiation from the sun, and in summer months the earths tilt is such that the sun’s rays hit the earth at smaller angles and so the radiation is more concentrated (Schroeder, 2011). 14 Therefore, there is a direct link between sunny weather (more concentrated radiation) and ozone production. However, there is also a link between temperature and ozone production (Figure 3).
13 Department for Transport. ‘Provisional Road Traffic Estimates Great Britain: Ap ril 2019 – March 2020’ . (2020, May 21). https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file /886199/prov-road-traffic-estimates-gb-april-2019-to-march-2020.pdf . 14 Schroeder, D.V. ‘The Sun and the seasons’ . (2011) http://physics.weber.edu/schroeder/ua/SunAndSeasons.html.
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