Diesel exhaust is a significant component of urban air pollution, containing a complicated mixture of gases and airborne particles, and Mr. Ryan Robinson, a PhD student at Imperial College London , UK, said that studies have proof that exposure to the diesel particles, which are down to 20 nanometres in diameter, was associated with harmful health effects.

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," said Robinson.

To understand how the diesel extract activated the airway nerves, the researchers used pharmacological and genetic knock out tools. They found that the responses to those diesel extracts were driven by activation of the TRP ankryin-1 (TRPA1) channel. They also discovered that the application of an antioxidant abolished the responses to the extract.

This research is, however, only a first step towards understanding how air pollution may be affecting airway sensory nerves and respiratory reflexes. Whether other types of fuel activate airway nerves remains to be seen, and it is even possible that they may have a far more potent effect in this area than diesel. It will also be crucial to determine whether increased activation of sensory nerves explains why some are more susceptible to the effects of air pollution than others, the researchers said.

The study will be presented at the 13th European Respiratory Society Lung Science Conference.