Studies in mice suggest that tumour growth is triggered by inflammation caused by tiny particles, rather than genetic mutations.

Air pollution could cause lung cancer not by mutating DNA, but by creating an inflamed environment that encourages proliferation of cells with existing cancer-driving mutations, according to a sweeping study of human health data and experiments in laboratory mice. The results, published in Nature on 5 April1, provide a mechanism that could apply to other cancers caused by environmental exposure - and might one day lead to ways to prevent them. “The idea is that exposures to carcinogens could promote cancer without actually doing anything to the DNA,” says Serena Nik-Zainal, a medical geneticist at the University of Cambridge, UK. “Not every carcinogen is a mutagen.” .....