A major smog indicator in China’s heavy industrial Beijing-Tianjin-Hebei region rose by more than a quarter in March, the Ministry of Ecology and Environment said on Friday, raising concerns that pollution is increasing with the end of winter output restrictions. Concentrations of PM2.5 – very fine respirable suspended particles harmful to human health – climbed to 80 micrograms per cubic metre in the region last month, an increase of 27 per cent from a year earlier, the ministry said. The region includes China’s capital and Tangshan, the world’s biggest steel-producing city. A six-month anti-pollution campaign that ended on March 15 required 28 Chinese cities to cut PM2.5 levels by as much as a quarter by slashing industrial output, restricting traffic and cutting coal use. During the first quarter, the levels of PM2.5 in the Beijing-Tianjin-Hebei region, which has been under heavy political pressure to tackle pollution, dropped 22.1 per cent to 74 micrograms per cubic metre, down from near record highs in the same period last year. Beijing air quality returns to hazardous levels as sandstorm, smog engulf city That indicates the output cuts were working as intended but their expiration has increased concerns that pollution levels are rebounding as factories, freed from restrictions, ramp up output. Nationwide, during the first quarter, PM2.5 concentrations fell 9.7 per cent from a year earlier to 56 micrograms per cubic metre in the 338 cities monitored by the ministry. But in March, average concentrations climbed 2.1 per cent year on year to 48 micrograms per cubic metre. Seven of China’s 10 most polluted cities in March were in Hebei province, China’s biggest steel-producing region. Tangshan and the city of Handan have already decided to extend the winter curbs until November. However, Xuzhou, an industrial city in eastern China’s Jiangsu province, was also on the list of the 10 smoggiest cities in March and during the first quarter, a sign that China’s smog is shifting from its northern heartlands as a result of the crackdown. Chinese city’s anti-smog plan slips up: big freeze sparks 42 road accidents after watered roads turn to ice The Yangtze River Delta region, which comprises Jiangsu, Zhejiang and Anhui provinces and the city of Shanghai, saw PM2.5 levels fall 4 per cent in March, but average levels rose 1.8 per cent in the first quarter as a whole. China is working on a new 2018-2020 action plan to tackle pollution, and experts have urged the government to introduce more targeted measures to tackle rising ground-level ozone, which has become a growing urban health threat. Chinese authorities are working to cut PM2.5 concentrations because the small size of the particles allows them to be inhaled deep into the lungs and their accumulation eventually can cause lung and heart disorders.