SHANGHAI (Reuters) - The Yangtze River delta region near Shanghai saw a key measure of smog concentrations rise by a fifth in January, official data showed on Monday, raising fears that the pollution crackdown in northern China has forced heavy industry to move further south.
Though concentrations of small, breathable particles known as PM2.5 fell 17.9 percent year on year to 64 micrograms per cubic meter in 338 cities nationwide in January, the Yangtze delta registered an average of 72 micrograms, up 20 percent.
The level remains far higher than the state standard of 35 micrograms. The World Health Organization recommends no more than 10 micrograms.
Xian, home of China's Terracotta Army in the country's northwest, was the worst-performing city in January.
The Pearl River delta region around Hong Kong also saw PM2.5 rise 3.9 percent year on year, data from the Ministry of Environmental Protection (MEP) showed.
China saw unusually high levels of PM2.5 in the first two months of last year, where near-record pollution throughout northern China prompted dozens of cities in the region to declare a "red alert" to impose emergency traffic restrictions and close factories and schools.
In a bid to meet their 2017 targets after the early year pollution spike, 28 northern Chinese cities pledged to cut PM2.5 by 10-25 percent from October 2017 to March 2018, forcing them to curb industrial output, reduce vehicle traffic and slash coal consumption.
The measures saw PM2.5 emissions fall by an average of 33 percent to 77 micrograms from October last year to the end of January, the environment ministry said in a separate notice on Monday.
It said Beijing cut pollutants 58.3 percent over the period, while Shijiazhuang, capital of Hebei province, registered a 52.4 percent decline over the four months.
China's anti-smog campaign has not been without controversy, with businesses complaining that Beijing's "one size fits all" approach has harmed their interests.
An over-ambitious attempt to convert millions of households from coal- to natural gas-fired heating has also proved a major challenge, with many villages left without gas supplies during parts of the freezing winter.
(Reporting by David Stanway; Editing by Eric Meijer)