Is COVID-19 improving air quality?

The air we breathe in the UK could be cleaner. The WHO thinks the UK has the 59th most polluted air in the world – but this still leads to around 40,000 premature deaths every year. As COVID-19 hits transport, work and business across the world, it would be reasonable to guess that air pollution had improved in cities. In reality, air pollution has only dropped slightly. The pollutants have mostly changed, rather than absolutely reduced.

Nitrogen Dioxide concentration - 2020

Some pollution decreased, but other pollutants actually rose. The most common components of air pollution are ozone, nitrogen dioxide, sulpur dioxide, and particulate matter (literally, anything microscopic in the air, like dust and bacteria). DEFRA maintains 150 air quality sensor stations across the UK, and this data shows reductions in lockdown. Nitrogen dioxide comes mainly from  vehicle emissions, like diesel cars, and is linked to respiratory diseases. A slow recovery to ‘normal’ levels of pollution can now be seen, though.

PM and Ozone concentrations

But overall, the UK’s air isn’t necessarily cleaner. Whilst nitrogen dioxide decreased, particulate matter and ozone levels rose, as can be seen above. Ozone is formed in sunlight from combustion fumes. Normally, nitrogen dioxide reacts with ozone and suppresses it, but lower nitrogen dioxide causes ozone to rise. PM movements are more complex – and is linked to wind movements from Europe, and agricultural fertilisers. Researchers are working to use historical data to correct the effects of weather on these findings, and findings show that there is a downward underlying trend. However, in absolute terms, PM10  and PM2.5 pollution is higher. 

Air pollution isn't changing how you might think in COVID-19 – even with transport ground to a halt Click To Tweet

Overall, some air pollution levels have reduced during the pandemic. Nonetheless, air pollution is a complex problem and it is changing, not going away. Air pollution remains an increasing problem despite COVID-19, and is here to stay. Lockdown shows us how deep changes need to be to truly tackle environmental problems. 

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