Walking and cycling even in the most polluted of cities is still better for you than staying indoors, a study from researchers at the University of Cambridge has shown. Regular exercise – walking, running, cycling – can slash people's risk of developing serious illnesses such as heart disease, diabetes, cancer and strokes, according to the National Health Service. There are worries, however, regarding the risks people exercising in towns and cities face from air pollution. A recent joint report from the Royal College of Paediatrics and Child Health and the Royal College of Physicians linked outdoor air exposure to around 40,000 deaths in the U.K. every year. As well as being connected to thousands of deaths, the report stated that exposure to outdoor air pollution costs the U.K. economy over £20 billion (US$28.2 billion) every year. However, the new study, conducted by researchers from the Centre for Diet and Activity Research (CEDAR), a collaboration between the University of Cambridge, University of East Anglia, and the Medical Research Council, found that the risks from air pollution would not "negate the health benefits of active travel in the vast majority of urban areas worldwide," according the University of Cambridge. "Our model indicates that in London health benefits of active travel always outweigh the risk from pollution," Marko Tainio, who led the study, said in a statement on the university's website. "Even in Delhi, one of the most polluted cities in the world – with pollution levels 10 times those in London – people would need to cycle over five hours per week before the pollution risks outweigh the health benefits." Tainio added. The team used computer models to examine the risks and benefits of differing levels of physical exercise and pollution in cities around the world. Their study was published in the journal Preventive Medicine. "Whilst this research demonstrates the benefits of physical activity in spite of air quality, it is not an argument for inaction in combatting pollution," James Woodcock, a senior author on the paper, said. "It provides further support for investment in infrastructure to get people out of their cars and onto their feet or their bikes – which can itself reduce pollution levels at the same time as supporting physical activity," Woodcock added.