The Clean Air Zone was introduced in Bristol in November 2022, to tackle high levels of poisonous air pollutants like nitrogen dioxide, which are emitted by motor vehicles. A landmark report has now been published evaluating its successes one year on. Nitrogen dioxide, which contributes to health problems like asthma, lung cancer and heart disease, is measured in many tiny tubes scattered around Bristol. Each month the diffusion tubes take a reading of nitrogen dioxide, providing scientists with an annual average. But what do locals think of the clean air zone?