asbestos

Asbestos is a group of naturally occurring fibrous minerals that can be split into thin, durable threads. Those very qualities — strength, heat resistance and being fireproof — made it a prized building and insulation material for much of the twentieth century. The problem is that the same needle-like fibres, once airborne and inhaled, are almost indestructible inside the body.

When asbestos fibres are breathed in, the longest and thinnest reach deep into the lungs, where the immune system cannot fully clear them. They lodge in lung tissue and the lining of the chest for decades, provoking chronic inflammation and scarring. Different fibre types vary in hazard, but all forms are considered harmful; the so-called amphibole fibres are particularly persistent and dangerous.

Asbestos exposure causes a spectrum of disease, typically appearing 20 to 40 years later: scarring of the lung (asbestosis), thickened patches on the pleura (pleural plaques), pleural effusions, lung cancer, and mesothelioma, an otherwise rare cancer of the pleura. Smoking multiplies the lung-cancer risk dramatically. Although many countries now ban or restrict it, asbestos remains in older buildings and in use in some regions, so exposure and new diagnoses continue today.