Air pollution in China has climbed back to its pre-pandemic levels, with scientists warning that Europe may follow suit.
Lockdowns prompted by the coronavirus outbreak led to dramatic drops in dirty air across the world as traffic and some industry ground to a halt. Air pollution causes at least 8m early deaths a year and cleaner skies were seen as one of the few silver linings of Covid-19. Experts have called for action to help retain the air quality benefits of the lockdown, with some measures being taken such as expanding cycle lanes and space for walking in cities around the world.
Data from the Centre for Research on Energy and Clean Air (Crea) shows concentrations of fine particles (PM2.5) and nitrogen dioxide (NO2) across China are now at the same levels as one year earlier. At the height of the country’s coronavirus response, in early March, NO2 levels were down 38% from 2019 and levels of PM2.5 were down 34%.
“The rapid rebound in air pollution and coal consumption levels across China is an early warning of what a smokestack industry-led rebound could look like,” said Crea lead analyst Lauri Myllyvirta. “Highly polluting industries have been faster to recover from the crisis than the rest of the economy.”
“As the first major economy to reopen after the crisis, all eyes are on China,” he said. “It is essential for policymakers to prioritise clean energy.” As well as industry restarting, analyst Wood Mackenzie predicts China’s oil demand, mostly used in transport, will recover to near-normal levels in the second quarter of 2020.
Air pollution has been linked to heart and lung damage and many other conditions including diabetes and damaged intelligence. It is likely to affect virtually every organ in the body. But pollution returned to China’s cities and industrial regions in mid-May. Even in Wuhan, the city at the centre of the epidemic, NO2 levels are now just 14% lower than last year, after briefly dropping by almost half. In Shanghai, the latest levels are 9% higher than last year.
European cities have also seen a big dip in air pollution during the virus outbreak. Data from the Copernicus Atmosphere Monitoring Service (Cams), which tracks pollution in 50 European cities, showed that 42 of them recorded below-average levels of NO2 in March. London and Paris had 30% reductions in NO2, which is mostly produced by diesel vehicles.
“We do expect pollution to rebound, but we have not been able yet to show that,” said Vincent-Henri Peuch, director of Cams. He noted that the Cams data is for average air pollution levels across cities: “Next to a busy road, the effect of traffic reduction will be higher – up to 70% or 80% [reduced pollution] in places.”
Distinguishing the pollution changes caused by the lockdowns and their subsequent relaxations from other factors, such as weather and chemical interaction of pollutants, is complex. Spring is also the most polluted season in western Europe in normal years, due to the start of the agriculture cycle causing ammonia emissions that go on to form particles over cities. The Cams team is now working with the Barcelona Supercomputing Centre to untangle these factors and produce robust estimates of the coronavirus effect.
Peuch said what happens to air quality in European cities remains to be seen: “We do not know how people’s behaviour will change, for example avoiding public transport and therefore relying more on their own cars, or continuing to work from home.”
Gary Fuller, an air pollution expert at Kings College London, said: “Rather than let this time be forgotten, the United Nations and environmental campaigners are urging governments to ‘build back better, to invest in the future not the past’, to ensure that our global recovery has sustainable legacy.”