From the article:

Men living in polluted areas are more likely to go bald than those breathing cleaner air, a new study suggests.

The ground breaking research, by academics at the University of London, has linked the onset of male pattern baldness, to environmental factors, such as air pollution and smoking.

The scientists believe toxins and carcinogens found in polluted air can stop hair growing by blocking mechanisms that produce the protein from which hair is made. Baldness is known to be hereditary, but the new research suggests that environmental factors could exacerbate hair loss.

Full text at Telegraph.co.uk — Pollution sends men bald

This is brand new and quite interesting material. It does shed light on one of the many environmental substances that can cause hair loss and the list gets longer.