Why diesel vehicles are more harmful

Researchers have shown how exhaust pollution from diesel engines affects nerves within the lung.

Identifying potential mechanisms linking exposure to diesel exhaust and the exacerbation of respiratory diseases may lead to treatments for those affected.

"Our results indicate that our reliance on fossil fuels, and particularly diesel, could have a detrimental effect on our health, supporting the idea that we should be looking towards alternative fuel sources," said Ryan Robinson, one of the researchers, from the Imperial College London.

Diesel exhaust is a significant component of urban air pollution, containing a complicated mixture of gases and airborne particles.

"Studies have shown that exposure to these diesel particles is associated with harmful health effects," said Robinson.

"These particles are very small - around 20 nanometres in diameter - and are therefore not only invisible to the naked eye, but can penetrate deep into the lungs," he added.

The lungs contain numerous sensory nerves that can detect potentially harmful stimuli and thus allow the body to respond, for example by triggering a cough.

"However, we know that these nerves can also be involved in exacerbating respiratory conditions, for example by causing the bronchi to constrict in diseases such as asthma," Robinson said.

The researchers found that the diesel particles from a forklift truck could activate airway sensory nerves in an in vivo anaesthetised guinea pig model.

"It was interesting to see that the more chemically sensitive airway nerves were involved, rather than the mechanically sensitive ones," Robinson explained.

The researchers then used an in vitro isolated nerve preparation that allowed them to probe the mechanisms involved more rapidly.

"The first thing we noted was that the chemicals isolated from an organic extraction of the diesel particles were key to the activation of the nerve," he added.

Robinson presented the study at the 13th European Respiratory Society Lung Science Conference.