Many children are being driven to school when they could walk or cycle - that's according to a joint report by the Institute of Directors and the sustainable transport charity Sustrans Cymru.
Their figures show three-quarters of school journeys in the Cardiff area are less than two miles – and almost three in 10 are under a mile.
The report claims that school run traffic is aggravating rush hour congestion and increasing costs for businesses.
As International Walk to School Month begins, people are being encouraged to leave their cars at home for short journeys.
Cardiff City councillors recently voted in favour of development plans which include improved public transport links in and around the city.