Activity in China’s factory sector shrank at its fastest rate in at least three years in August as domestic and export orders tumbled, increasing investors’ fears that the world’s second-largest economy may be lurching toward a hard landing.

Markets are turning turbulent again after investors were unnerved by more signs of weakness in China, the world’s second-largest economy.

Business is roaring at Qiu Bangsheng’s factory in eastern China, where whizzing machines churn out long, white strips of polypropylene that are rolled into cylinders and turned into nappies and other hygiene products.