Why is China’s air pollution shifting west?

China has had astonishing success improving its air quality since declaring a “war on pollution” in 2013. From 2014 to 2022, average levels of fine particulate matter (PM2.5)  dropped  faster than in any other country, according to the University of Chicago’s Air Quality Life Index. Last year, nearly  three-quarters  of the country’s cities had average PM2.5 levels below the national standard limit. Taken together, the level of PM2.5 in China’s cities was 36% lower than it had been in 2015. This success followed a range of measures including retrofitting coal power plants.

China’s efforts at managing air pollution have hitherto focused on the eastern parts of the country. The national air pollution  action plan  that the State Council issued in 2013 set PM2.5 targets for cities clustered in the Beijing-Tianjin-Hebei area, and in the deltas of the Yangtze and Pearl rivers. In 2018 came  another action plan , this time focussed on improving air quality in Beijing-Tianjin-Hebei, the Yangtze Delta and the Fenwei Plain on the middle reaches of the Yellow River. (The Pearl River Delta had been dropped due to its long-term good compliance with the national standard.) These three regions all have an energy mix dominated by coal, and significant air pollution issues connected with heavy industry.

But while in the first quarter of 2025, eastern China’s overall air quality  improved , pollution rose in provinces to the south and west of the country. PM2.5 levels in Guangxi, Yunnan and Xinjiang were substantially higher than a year earlier, at 32%, 14%, and 8% respectively.

Apart from time-limited weather factors in several southern regions, this is largely the result of heavy industry, such as steelmaking and coal processing, moving to the south and west of the country where energy is more abundant. What is needed to improve the situation is better integration of renewable power into the grid, the electrification of industrial processes that currently rely on coal, and the continued expansion of clean-energy generation.

The westward shift

In the first quarter of 2025, the average PM2.5 levels of China’s cities was  down  5% year on year. Levels of major pollutants such as sulphur dioxide (SO2), nitrogen dioxide (NO2) and PM10 particulates – which correlate closely with industrial activity and fossil fuel use – declined or remained stable. However, in some provinces to the west and south, air pollution went up.

Guangxi, Yunnan and Hainan in particular experienced large increases, with PM2.5 levels growing by 32%, 14% and 11% respectively. Xinjiang, with an 8% rise and a yearly average level of 70 micrograms per cubic metre (µg/m³), took over from Henan as the province with the worst airborne particulates problem. Its PM2.5 measure is now double the  national standard  of 35 µg/m³ and 14 times the  guideline value  adopted by World Health Organisation (WHO).

During that quarter, PM2.5 levels rose year-on-year by 22.6% in Kunming, Yunnan and by 10.1% in Urumqi, Xinjiang. These increases were primarily driven by anthropogenic emissions rather than meteorological conditions, according our  analysis  at the Centre for Research on Energy and Clean Air (CREA). In Kunming, 11.9% of the rise was down to anthropogenic emissions and 10.7% to the weather. In Urumqi, the share was 9.2% versus 0.9%. Anthropogenic emissions were also primarily responsible for the 12.6% and 5% increases seen in the cities of Yinchuan, Ningxia, and Xi’an, Shaanxi, despite overall levels in both those provinces falling. In addition, while levels are down in traditional industrial regions such as Shanxi, north-east China, and the Beijing-Tianjin-Hebei region, anthropogenic emissions continued to exert a positive pressure on pollution levels. This suggests pollution levels may still rise in these regions when weather conditions are slightly adverse.