Exchange visits can be risky affairs, but no one expects them to be life-threatening. When a group of Danish pupils visited York two years ago, however, they got a nasty shock. The problem was that it was a cycling exchange - and they were too scared to get on their bikes. "They were terrified," says Jay Sayers, head of English at Burnholme Community College, one of the two schools involved in the exchange. "They said, 'We don't want to go cycling on these roads. Don't leave us!' We had two near-misses. And they all noticed the disgusting smell of carbon monoxide in York."
Things had been very different when 32 pupils from York had visited Odense earlier in the year. "They cycled off with their friends and that was it," says Ms Sayers. "They went to the swimming pool, into town, to the football stadium, anywhere they liked. They absolutely loved it. I was amazed. I could not believe you could have a society like this in a city."
In Denmark the children found cycle lanes, mini cycle roads, fewer cars driving much more slowly, and drivers making eye contact with cyclists. It all made for a safer, less stressful environment, where the benefits seemed to stretch beyond the mechanics of merely getting around.
In Britain we have grown so used to life on our traffic-choked island that congestion, accidents, noise, dirt, pollution and the lack of freedom to cycle and walk seem normal.
Few of us stop to examine the price we pay for the luxury of car travel. In the Seventies, 72 per cent of primary schoolchildren walked to school, but that figure is now down to 59 per cent and falling, and one in five morning rush-hour vehicles is on the school run. The knock-on effects on children's social, cognitive and physical development are formidable.
Chauffeured children might feel safe from stranger-danger and being run over, but they are also bubble-wrapped against the social life of walking to school, the independence they learn by doing it, and the things they experience on the way. They arrive in school with their lungs full of pollutants (air drawn in through a car's air conditioning system in slow-moving traffic can be fouler than the air on the pavement), but with their bodies and minds unstretched, and with no resources to draw on when asked to write a poem about walking in the rain.
Denied the freedom to assess small daily risks, they may fall flat on their faces when the bigger risks of teenage life come their way, says Jackie Lang, former president of the Girls' School Association.
The Institute of Child Health says that walking to school accounts for 41 per cent of children's walking, and sedentary children produce sedentary adults. Car-coddled infants could well face a future of obesity, heart disease, hypertension, mental health disorders, diabetes and osteoporosis.
Yet we love our cars so much that it will take radical measures to make us change. This summer's transport White Paper was a start. It aims to persuade one in 10 car owners to give up their wheels, and the rest of us to use public transport more often. And earlier this week the Government launched its "quality of life" barometer with the consultation document Sustainability Counts, in which road traffic and air pollution are identified as two of 13 high-level indicators of "clean growth".
But often it is compulsion that brings results. The Royal School in north London, an independent girls' school, has reduced car runs by 23 per cent since 1996, because its council, Camden, required it to do so in order to gain permission to increase pupil numbers. The school was forced to persuade parents to car-share, to disseminate information about other forms of transport, and to offer teachers interest-free loans for season tickets. "We wouldn't have done a thing if we hadn't been made to do so," admits bursar Michael Rixon.
Camden is about to unveil a green travel plan, including a network of safe routes to school. According to Sustrans, the civil engineering charity which has been promoting safe routes to school since l995, more than 70 local education authorities are now encouraging pupils to walk and cycle to school. For most schools this means traffic-calming measures, safe cycle routes and pedestrian crossings, but others are coming up with more imaginative approaches. "One school in Reading, Berkshire, makes parents of its new pupils walk a sensible route to school with their children in the first week of school," says Celia Beeson, liaison officer for the Safe Routes to School project. "It also holds cars back on the school site until all pedestrians, cyclists and school buses have gone, which reduces the time advantage of driving in to pick up children." In York, the Safe Routes to School scheme is also having an impact. Since Burnholme College's cycling exchange with the Danish pupils, a 20-mile an hour zone has been introduced outside one of the city's comprehensives, and extensive cycle lanes have been laid.
In Hertfordshire, one primary school, Wheatfields Junior in St Albans, has a "virtual bus".Children wait at pick-up points for a trolley which they load with their bags before walking to school in a crocodile with supervising parents. The Pedestrians Association has run "Walk to School Weeks" for several years now, but this summer Birmingham council went a step further with "Walk on Wednesdays", a scheme encouraging pupils to walk to school at least one day a week throughout the year.
Some teachers try to lead by example. Bill White of Temple Moor High School in Leeds normally walks the two miles to school. "The kids say, 'You not got a car, Mr White?' Then they want to know why I don't use it. I say, 'It's because I don't want to knock you over, and I don't want to give you asthma'. But they don't get it. Cars are status symbols. They can't wait to get them. You're having to fight both implicit and explicit messages."
Perhaps the most powerful propaganda of all is discovering - as those children from York did - how much better life can be when the car is no longer king.
Further information from Walk to School, tel: 0171 490 0750
TEN TONS OF TROUBLE
1 Ten million more cars are expected on the road by 2025.
2 Ten people a day die on roads in Great Britain, and 45,000 are killed in Europe each year.
3 Britain has one of the worst child pedestrian casualty rates in Europe. The highest casualty rate is among girls aged 10-l5.
4 The biggest killer is speed. At 40 miles an hour, nine in 10 pedestrians hit by a vehicle will die; at 30 miles an hour, five in 10 will die; at 20 miles an hour only one in 10 will die. The danger is multiplied if the vehicle is fitted with metal bull bars (despite a campaign, still unregulated).
5 One in 25 adults, and one in seven children, has asthma. Traffic pollution triggers attacks.
6 Parents overestimate the risk of stranger-danger, but underestimate road risks. Of more than 2,000 parents quizzed by the University of Newcastle, only 18 per cent let their children go alone to the park to play, but 61 per cent let them cycle without a helmet.
7 Change can happen. People objected to seat-belt and drink-driving laws when they were introduced, but now accept them.
8 Technology may come to our aid. In 10 years' time we could have smart cars that slow automatically at speed limits.
9 Solutions exist. Edinburgh council has already managed to cut bus journey times by a third. The next step is to ring the city with electronic toll booths, offering drivers a choice of paying to get into the city or parking and riding on a high-speed transit network. A housing project is being built without garages to deter car ownership.
10 We still do stupid things - like designing a traffic-free Millennium Village in the shadow of the Dome, then siting a four-lane highway and roundabout between the village and its supermarket.
* JOIN THE DRIVE FOR FREEDOM
Drive less. Walk and cycle more
If you must drive, do so slowly and choose an environmentally friendly car.
Talk to pupils about their transport preferences.
Get to know safe routes to school
Make sure your school teaches road safety.
Dissuade parents from driving children to school.
Discuss traffic issues in the classroom.
Support walking and cycling campaigns.
Use your imagination: picture life with less traffic.