An increasing number of research studies are showing that low emission zones (LEZs) improve health.
More than 320 zones are operating across the UK, Europe and notably in Tokyo, Japan. These reduce air pollution across an area by curbing the number of highly polluting vehicles, normally older diesels. Schemes, including London’s ultra-low emission zone, can improve air quality. This should lead to improved health, but does this actually happen?
A new review, published in the Lancet Public Health journal, has gathered research on schemes in cities around the world. Rosemary Chamberlain, from Imperial College London, who was part of the review team, said: “We wanted to bring together the most up-to-date studies from LEZs globally, to understand their effectiveness and to inform future plans to address air pollution.”
LEZs are not the same everywhere, making them hard to compare. Some apply to lorries and buses only, while others also include taxis, cars and motorcycles. The health researchers in each country also used different approaches and different data sources. The studies compared data before and after the LEZ start date and some also made comparisons with areas with no LEZ. Data came from health survey results, GP and hospital records, and death registrations.
Despite these differences in approach, five of the eight LEZ studies showed a clear reduction in heart and circulatory problems when an LEZ was implemented. These included fewer admissions to hospital, fewer deaths from heart attacks and strokes, and fewer people with blood pressure problems. These results came from zones in Germany, Japan and the UK. One of the German studies analysed hospital data from 69 cities with LEZs. It found a 2%-3% reduction in heart problems and 7%-12% reduction in stroke. The improvements were greatest for older people and resulted in estimated health cost savings of €4.4bn (£3.8bn).
Not all studies found the same results. Five studies, again covering zones in Germany, Japan and the UK, looked at breathing and lung problems. Two found improvements and the remainder showed no definite result. None showed a clear deterioration.
Chamberlain explained: “This review shows that LEZs are able to improve health outcomes linked to air pollution, with the evidence being most consistent for cardiovascular disease, such as heart disease and strokes. It is, however, too soon to fully judge the long-term benefits.”
The latest evidence on the effects of air pollution tells us that the health damage from air pollution accumulates over our lifetimes. Cancer from air pollution is the most obvious example, but it also hampers children’s physical and cognitive development and adds to chronic diseases in later life, including osteoporosis and dementia. The LEZ studies were not long enough to show these types of lifetime effect, although two studies on German zones showed that health benefits tended to grow over three- and five-year periods. One study, of the Tokyo zone, detected improvements in lung cancer rates six to nine years later.
Prof Dan Greenbaum, of the US Health Effects Institute, said: “When we implement a new air quality action, we estimate what its benefits might be, but it is always good to test to see if it had the predicted effects. A growing body of evidence, including this strong new analysis, shows that actions can reduce exposure and improve health.”
