Balding and hair loss could be caused by pollution, according to a new study.
Scientists exposed cells from the base of hair follicles and human scalps to both particulate matter (PM) and diesel particulate - and after 24 hours the amount of protein responsible for hair growth decreased.
PM is released into the atmosphere when fossil fuels such as oil and coal are burnt.
It is also produced by the mining and manufacturing industries.
The study was carried out by scientists from the Future Science Research Centre in South Korea.
The research was presented at the 28th European Academy of Dermatology and Venereology Congress in Madrid, Spain.