Air pollution on the rise in China as coronavirus lockdown ends

Nitrogen dioxide, an air pollutant linked to a range of health issues, is on the rise as industry ramps up, new satellite data shows

Air pollution in China is on the rise following the end of the coronavirus lockdown, satellite data has revealed.

Nitrogen dioxide (NO2) pollution increased as the country began to reopen last month. NO2 levels, represented by colour density on the maps, are seen to intensify over areas including Wuhan, the suspected epicentre of the outbreak, Beijing, Shanghai and Hong Kong.

The maps were created using readings from the Sentinel-5P observation satellite, following guidelines by the European Space Agency, and first appeared in the META newsletter of the European Environmental Bureau, (EEB), a network of organisations from more than 30 countries.

The satellite carries an instrument - the Tropospheric Monitoring Instrument known as Tropomi ​- to map trace gases in the atmosphere such as nitrogen dioxide, ozone, formaldehyde, sulphur dioxide, methane, carbon monoxide and aerosols, which affect air quality and the climate.

The emissions data covers a roughly four-month period, from 12 December, 2019 to 28 April. It showed that emissions dropped significantly between 25 January and 23 February.

On 23 January, China blocked people from leaving or entering Wuhan and expanded the lockdown to most of the province in the following days. Train service and flights were cancelled and checkpoints were set up on roads.

China also ordered a widespread lockdown across most of the country, confining hundreds of millions of people to their homes. Travel was severely curtailed, businesses shuttered and vast swaths of the population were instructed to work from home.

China has reported 4,643 deaths and more than 84,000 cases of the coronavirus to the World Health Organisation, although the numbers are believed to be higher, according to a US intelligence report.

The lockdown ended on 8 April and as business, travel and industry began ramping up, so emissions have climbed.

EEB air policy officer Margherita Tolotto said: “During this pandemic, what happens in China has often been a window into what happens elsewhere some time later. Breathing toxic air compromises our health and makes us more vulnerable to health threats. Our governments and the European Commission must prevent harmful air pollution from returning and develop exit strategies which avoid taking us back to a dirty future.”

Nitrogen dioxide levels in China. Top, between 25 January and 23 February and below, 30 March to 28 April (EEA / EEB / James Poetzscher)

Nitrogen dioxide levels in the atmosphere in part come from cars, trucks, buses and power plants. The air pollutant forms when fossil fuels like coal, oil, gas or diesel burn at high temperatures. Along with other nitrogen oxides, NO2 contributes to particle pollution in the air.

The air pollutant can cause a range of health issues, according to the American Lung Association, including increased inflammation of airways; cough and wheezing and reduced lung function. The group also points to new research which warns NO2 to be the likely cause of asthma in children.

According to the European Public Health Alliance (EPHA), people who live in polluted cities are more at risk from the coronavirus. Poor air quality has been linked to hypertension, diabetes and respiratory diseases, conditions that place Covid-19 patients at greater risk.

A 2003 study on SARS found that patients in regions with moderate air pollution levels were 84% more likely to die than those in regions with low air pollution, EPHA reported.