According to the Helsinki-based Centre for Research on Energy and Clean Air (CREA), levels of harmful PM2.5, NO2, SO2 and ozone have now exceeded those recorded at the same time last year.

While industrial emissions are mostly to blame, the CREA noted that densely populated cities liked Shanghai and Beijing are still enjoying lower levels of air pollution compared to last year.

The Covid-19 lockdowns had a dramatic impact on China’s fossil fuel consumption and air quality. In the 30 days after the Chinese New Year holiday was originally scheduled to end, on 3 February, national average PM2.5 levels fell by 33 per cent, while NO2 levels dropped by 40 per cent compared to the same post-holiday period in 2019. 

CO2 emissions fell by an estimated 25 per cent, with coal-fired power generation, cement manufacturing and oil consumption all plummeting.

CREA said that China’s emphasis on construction and manufacturing projects could lead to a “dirty” recovery from the pandemic that would see many of the most polluting sectors become the most prominent drivers of economic activity.

The Chinese government’s plan to recover from the 2008 financial crash, for example, ushered in an unprecedented wave of construction projects and record levels of coal, cement and steel consumption.

The stimulus programme culminated in the horrendous air pollution episodes around Beijing during the winter of 2012-13, commonly known as the “airpocalypse”.

Nevertheless, this outcome is not a given, as the rapid increase in output from energy-intensive industries and coal-fired power generation from 2017 to 2019 was offset by sweeping air quality efforts.

Thousands of industrial boilers and millions of households were switched from coal to gas and electricity and massive investments in end-of-pipe emissions controls at power plants and factories ensured that while air quality gains slowed, they did not reverse.

PM2.5, NO2, SO2 and ozone - the four pollutants measured by CREA - have all been shown to have severe health impacts and their concentrations in China remain far above safe levels.

Overall, the number of people travelling around China is still below last year's levels, but the shift from public transport to private cars and the return of congestion in urban areas due to worries about infection risk has worsened the air pollution impact on a per passenger basis.

Improvements in air pollution have also been seen in Europe in recent months, with CREA estimating in April that 11,000 deaths had been avoided as a result.