Chronic health disorders linked to obesity, smoking, high salt intake, and pollution are mounting in China, as Asia’s largest economy grapples with the burdens of rapid growth and affluence. A new study published in the Lancet finds chronic illnesses including stroke, hypertension, and lung cancer are now the leading causes of premature death in China, replacing lung infections and neonatal disorders. That shift reflects declines in maternal and child mortality rates over the past three decades, as well as the success of government programs to bring infectious disease rates under control. But because chronic diseases are expensive to treat, the change is likely to drive up health care costs in China. China now spends only about 5% of the gross domestic product on healthcare, compared with 17% in the United States, according to the World Health Organization.