Air pollution significantly increases the risk of low birth weight in babies, leading to lifelong damage to health, according to a large new study. From a report: The research was conducted in London, UK, but its implications for many millions of women in cities around the world with far worse air pollution are "something approaching a public health catastrophe," the doctors involved said. Globally, two billion children -- 90% of all children -- are exposed to air pollution above World Health Organization guidelines. A Unicef study also published on Wednesday found that 17 million babies suffer air six times more toxic than the guidelines. The team said that there are no reliable ways for women in cities to avoid chronic exposure to air pollution during pregnancy and called for urgent action from governments to cut pollution from vehicles and other sources.