We’re raising this issue, coincidentally, on the day when the air pollution in Cardiff is at dangerous levels because of the combination of ozone levels and the particulates from vehicles. Professor Sir David King, who’s the former chief scientific adviser to the UK Government, recently said that children sitting in the back seats of vehicles are likely to be exposed to dangerous levels of air pollution in a box collecting toxic gases from all the vehicles around you’.

Professor Stephen Holgate, an asthma expert at Southampton University and chair of the Royal College of Physicians’ working party on air pollution, said that there’s enough evidence to tell parents that walking and cycling exposes their children to less air pollution than driving. There’s a nine to 12 times higher a risk of air pollution inside the car than outside. They’re in the back of the car, mainly, children, and, if the fan is on, they’re just sucking the fresh exhaust coming out of the car or lorry in front of them straight into the back of the car’.

We know from the research that we’ve already got that this increases the risk of reducing the growth of their lungs, of becoming asthmatic. There is also some growing concern that it may stunt children’s ability to learn at school and may damage their DNA.

This is pretty substantive evidence, so I wondered what advice your public health experts give to headteachers, who can, in turn, pass it on to parents, to make it clear to people that it is much safer for them to walk and cycle to school than it is to take their children in a car.