Ambient air pollution is a major public health concern. It has prompted novel policy interventions, in the UK and beyond, notably in the form of Low Emission Zone (LEZ) and Ultra-Low Emission Zone (ULEZ) schemes. This policy brief explores the impact of these schemes on physical health and mental well-being, using large survey and administrative data covering the whole of England. It finds that these policy interventions have significantly reduced levels of key pollutants, leading to improvements in physical health and mental well-being, and a reduction of hospitalisations for respiratory problems. This effect has been particularly strong for the Central London ULEZ scheme, the toughest of the clean air policies, but we also see positive health impacts in other major cities in England that have implemented LEZ-type policies. Our evidence suggests that these schemes offer good value for money, with a back of the envelope cost-benefit analysis indicating savings of more than £963 million for the overall population.