In 1952, a week -long smog in London killed around 12,000 people. More than 70 years later we are yet to achieve air that does not harm our health. Over 60 thousand papers have been published on air pollution and health. Over half of these have been published in the last ten years. Globally we are exposed to more air pollution than ever before. We now know that air pollution harms our health at all stages of life from pre-birth, through childhood and during our time as adults, but policies and actions remain rooted in the science of the 20th century and not the new knowledge from the last decades. Our inability to solve this problem does not stem from a lack of evidence but from a lack of implementation, despite evidence that reducing air pollution improves health and is massively cost beneficial. The problem is not intractable but recent public controversy makes it ever harder for evidence-based actions.