Air Quality Expert Group - Rapid evidence review

Air pollution context and climatology – learning from COVID-19 lockdowns

Nationwide reduction in transport intensity began mid-March, reached a minimum in early April. Major sectors contributing emissions of NOx, VOCs and PM.

The UK has had unusual meteorology in 2020. Post-lockdown - significant Easterly component, with transboundary pollution contributions

Air Quality Expert Group - Rapid evidence review

Significant reductions seen UK-wide in NOx and NO2

Top: Raw data from 225 air quality measurement sites across the UK. Bottom: Same data but corrected to account for meteorological variability

Reproduced from Marner, B., Air Quality Consultants, 2020.

Air Quality Expert Group - Rapid evidence review

o Compared to 2019, PM2.5 higher during lockdown - due to Easterly weathero But using computer models, PM2.5 has been lower in many places compared to a

business-as-usual scenario.o Highlights significant AQ influence of wider European emissions.

Reproduced from: Keller C. and Evans, M.J., University of York andNASA Goddard Space Flight Center, 2020.

Business as usual

2020 actual

Changes in PM2.5 are more complex to quantify

Air Quality Expert Group - Rapid evidence review

Reproduced from: Williams, M., on behalf of the Environmental Research Group, King’s College London, 2020.

Exposure to pollution depends where you live, work and how you commute

o Less commuting reduces exposure in London, but could be offset by higher indoor pollution, for example from additional cooking.

Air Quality Expert Group - Rapid evidence review

Lower NOx emissions in isolation can lead to local increases in ozone

Business as usual

10% lower NOx

Lower NOx & VOC

Forecasts of a Springtime ozone case study under COVID-19 emissions

Forecasts of a summertime ozone case study under COVID-19 emissions

30% lower NOx 50% lower NOx

Lower NOx

o Emphasizes the importance of managing all the key pollutants together with coherent strategy that recognizes the chemical interconnections

Reproduced from: Agnew, P., et al. Met Office, 2020 and Fakes, L. and Evans, M.J., NCAS / University of York, 2020.