Exhaust fumes from diesel vehicles “definitely cause cancer”, a team of experts working for the World Health Organization (WHO) have said.

They concluded that diesel exhausts were a cause of lung cancer and could be a contributory factor in the development of bladder cancer.

The International Agency for Research on Cancer (IARC), a part of the WHO, said everyone should try to reduce their exposure to diesel exhaust fumes.

In 1988, the IARC classified diesel exhausts as probably carcinogenic to humans – now it says they are a definite cause of cancer.

People can be exposed to diesel exhausts in everyday life, whether through their work or through the ambient air.

Sources of exposure include motor vehicle exhausts, other diesel engines, and from power generators.

Dr Christopher Portier, chairman of the IARC working group, said: “The scientific evidence was compelling and the working group’s conclusion was unanimous: diesel engine exhaust causes lung cancer in humans.

“Given the additional health impacts from diesel particulates, exposure to this mixture of chemicals should be reduced worldwide.”

The WHO body also found petrol exhausts were possibly carcinogenic to humans, a finding unchanged from previous evaluations.