Kim Willsher

Paris: Want to save the planet? Wear your jeans two days a week, wash them every fifth day, and let them dry by themselves. Or better still do not wash them at all. And do not even think of ironing them.

This is the conclusion of a report commissioned by France's environment agency on the ecological impact of a pair of denims. The study looked at an "average" pair of jeans made of 600 gm of denim, lined with 38 gm of polyester, with six rivets and a button, worn one day a week for four years, washed every third time in a high-energy machine at 40 degrees C and, in a singularly French twist, ironed before wear.

The study, by the research firm Bio Intelligence Service, looked at the jeans' life cycle, from material production to daily use of the garment. It concluded that a French jeans wearer would damage the environment the least by buying denims made of cotton from a country not too far from Europe with strict anti-pollution laws. Machine washing, tumble drying, and ironing caused 47 per cent of the eco damage the jeans caused 240 kWh of energy a year, equal to using 4,000 light bulbs, each of 60 watts, for an hour. Dry cleaning was "an environmental disaster."

The author of the report, Nadia Boeglin, suggested minimising the impact on the planet by giving jeans away or cutting them down to make shorts.

Guardian Newspapers Limited 2006