That's the size of the problem

The size of PM10 particles may be the key to their impact on human health.

William MacNee, professor of respiratory and environmental medicine, and colleagues at Edinburgh University are learning how exposure to inert carbon pieces less than 10 microns in diameter can worsen respiratory diseases and increase cardiopulmonary mortality among susceptible individuals.

A series of experiments, the latest published in the journal Toxicology and Applied Pharmacology , are pointing to a complex chain reaction. It seems that the particles cause an oxidative chemical reaction in the lung lining involving the particles' large surface area to mass ratio and metals such as iron. Transcription factors sensitive to oxidative stress respond by switching on inflammation genes in lung cells, which may lead to the observed health problems.