Flint disease, also called chalicosis (a form of pneumoconiosis), is caused by the inhalation of stone dust, usually by those regularly cutting stone. Once inhaled, tiny particles of stone travel through your respiratory system, moving freely through larger passages and finally ending up in air sacs called alveoli. In the alveoli, small blood vessels called capillaries nourish your blood with oxygen and remove harmful carbon dioxide. When stone dust particles pass into the alveoli, they scrape the tissue and cause it to inflame. Scar tissue develops and swells around the invading stone dust particle, making the air sacs stiff and difficult to expand and fill with air. It is important to note that inhaling stone dust does not necessarily cause flint disease, because your body has ways of removing unwanted particles, such as mucus and cilia (tiny hairs in the airways), both of which help you to cough up the invading substance.