The environmental and social costs of the impacts are estimated at £9bn per year with more than half due to road congestion. Consumers travel an average of 898 miles a year by car to shop for food and the quantity of food transported by heavy goods vehicles has doubled since 1974. Food transport now accounts for 25% of all HGV vehicle kilometres in the UK.

The government is working with the food industry to reduce this by encouraging widespread adoption of best practice and by measuring performance. It has consulted on proposals in the draft Food Industry Sustainability Strategy developed with stakeholders and published for consultation in April that the sector prepare by 2006 a plan for achieving a 20% reduction in the environmental and social costs of food transport by about 2012.

The report shows that in general higher levels of vehicle activity lead to higher environmental impacts. But it is not a simple matter of so-called 'food miles'. The mode, timing, location and efficiency of food transport is important as well as the distance.

Sustainable Food and Farming Minister Lord Bach said: "This study is an interesting contribution to the 'food miles' debate. It shows that the issue is complex and that a range of factors have an effect on the overall impacts of food transport, not purely the distance travelled by individual products. We will update and publish these trends each year and I hope it will lead to a healthy debate between consumers, food producers, supermarkets, environmental groups and public authorities."

"It provides some pointers for consumers. For example internet buying and home delivery can cut vehicle kilometres and reduce road congestion. It shows that buying local products has the potential to greatly reduce the distance food is transported but that the benefits can be offset by increased road congestion if they are supplied in a less transport efficient way."

"It is clear that organic and seasonally-available food can reduce environmental impacts but that these can be offset by the way they are transported to the consumer's home. It is also clear that transport and trade of food has the potential to lead to economic and social benefits, for example, through economic gains for both developed and developing countries, reduced prices for consumers and increased consumer choice."

Headline findings include:

The environmental, social and economic costs of food transport are estimated at £9bn per year of which £5bn is due to road congestion, £2bn is due to road accidents, £1bn is due to pollution and £1bn to other factors. Looked at another way food shopping by car accounts for 40 per cent of the total costs.

Food transport produced 19 million tonnes of carbon dioxide in 2002 of which 10 million tonnes were emitted in the UK, representing 1.8 per cent of the total annual UK CO2 emissions.

'Food miles' alone is too simple a concept to capture the impacts of food transport. Instead the report recommends focussing on four aspects all of which are proposed in the draft Food Industry Sustainability Strategy as key performance indicators of the food industry's sustainability:

• To cover the impact on road congestion the report recommends monitoring distances travelled transporting food in urban areas. Urban food kilometres increased 27 per cent between 1992 and 2002.
• To cover wider congestion the report recommends monitoring food transport by heavy goods vehicles. Food transport accounts for 25 per cent of all HGV vehicle kilometres in the UK.