As much as one billion tons of waste could be burned in open and uncontrolled fires around the world each year, according to one estimate – close to half of all the municipal solid waste generated on Earth. But even if the true total is a fraction of that amount, the impact on human health and the environment is likely to be profound, particularly for the hundreds of millions of people living in countries throughout the global south where burning rubbish outdoors is the main method of waste treatment.