China air cleaner as NOx levels fall

A recent study published in the journal Environmental Science and Ecotechnology has revealed a significant decline in nitrogen oxide (NOx) emissions from human activities in China since 2020.

Nitrogen oxides (NOx) form aerosols and ozone in the atmosphere and are significant contributors to air pollution, acid rain and climate change.

The research was conducted by a team of scientists from China and France. The study employed satellite observations and air quality modeling techniques, and the results suggest a promising trend in China’s battle against air pollution.

The decline in NOx emissions was due primarily to:

  1. stricter air pollution control measures implemented by the Chinese government in recent years which have significantly reduced emissions from industrial facilities and transportation sectors and have demonstrably curbed NOx emissions at their source; and
  2. A reduction in transportation-associated emissions, largely due to the COVID-19 lockdowns, which slightly lowered China’s NOx emissions in 2020.

In 2021 and 2022, reductions in NOx emissions were achieved within the industrial and transportation sectors through stringent air pollution controls. These controls appear to have accounted for more than 70% of the total reduction.

According to a 2023 report by the China National Environmental Monitoring Center, the concentration of nitrogen dioxide (NO2), a major component of NOx, in China’s major cities decreased by an average of 33% between 2013 and 2022.

The reduction was corroborated by data from two independent spaceborne instruments—the TROPOspheric Monitoring Instrument (TROPOMI) and the Ozone Monitoring Instrument (OMI).

These studies found the reduction is largely attributed to the implementation of stricter vehicle emission standards, which mandated stricter limits on nitrogen oxide emissions from new vehicles.

Additionally, the closure of coal-fired power plants and the transition to cleaner burning natural gas have also contributed to the decline in NOx emissions from industrial facilities.