Green fuels used in school buses may increase asthma rates, warn experts.
American experts believe that the bio fuels made from corn, sugar cane and rapeseed can cause more damage to quality of air than normal fuels.
They found that when diesel was mixed with bio-fuels to power school buses it released 80 per cent more dangerous particles into the air that can lead to asthma.
"Poor air quality can have a major effect on our health and risks making life worse for people with respiratory conditions like asthma and emphysema," the Mirror quoted local government green group LACORS, as saying.
However, the councils have written to ministers seeking suggestions and asking about any links between bio-fuel and air quality.
The Government claims the fuels reduce pollution by 50 to 60 per cent.