SHANGHAI (REUTERS) - China's air quality improved last year, benefiting from Covid-19 related shutdowns as well as tougher industrial controls, government data showed.

Concentrations of lung-damaging small particles known as PM2.5 in 337 cities fell an average 8.3 per cent to 33 micrograms per cubic m over the year, according to the Ministry of Ecology and Environment.

The smog-prone region that encompasses Beijing, the city of Tianjin and the province of Hebei saw average PM2.5 levels drop 10.5 per cent to 51 micrograms per cubic m, though that was still higher than the national standard of 35 micrograms.

The World Health Organisation recommends annual mean concentrations of no more than 10 micrograms.

Anyang, a major steel- and coal-producing region in Henan province, was the worst-performing city in China for the second year in a row.

Haikou, capital of the island province of Hainan, was the best overall performer.

Smog experts have expressed concern that some northern cities in China are at risk of falling short of their winter pollution targets after a surge in the production of steel and cement.

Data for December showed, however, that despite the production hikes, average PM2.5 concentrations fell 3.6 per cent to 53 micrograms per cubic m.

The Beijing-Tianjin-Hebei region also saw concentrations decline by 6.2 per cent to 76 micrograms, with the region benefiting from windy weather.

Improvements in China's water quality were also made last year.

Some 85 per cent of surface water samples taken from nearly 2,000 sites across the country met standards for human use, up 7 percentage points over 2019.