Children are exposed to 30 per cent more air pollution than adults when walking to school because they are shorter, and nearer to exhaust fumes, a new report has found.

Parents are being urged to pick quieter roads to protect them from toxic air and also ditch the car, because pollution inside vehicles is 50 per cent higher than on the pavement.

Inhaling pollution raised their risk of health problems for youngsters including heart problems, asthma and potentially reducing the growth of their lungs.

But their exposure to pollution is 2.5 times lower if they take a route along quiet back streets than if they walk along busy roads, research for environmental charity Global Action Plan has revealed.

Chris Large, senior partner from the campaign group, said: “Millions of children in the UK that are walking to school along busy roads are potentially being exposed to 30 per cent more pollution than their parents.

"A simple solution for parents would be to choose quieter back routes to walk or cycle their children to school, away from the traffic, thereby reducing their exposure to unnecessarily high levels of damaging air pollution."

For the research, children and adults across four UK cities - Manchester, Leeds, Glasgow and London - carried an air pollution monitor for 10 minutes while walking along a quiet route, a busy road, a journey by car in traffic and on a bus.