This can then break apart into tiny fibers that float in The fibers get inhaled and get stuck in the mesothelium, which is the protective lining of the heart, lungs, and abdomen. Frequent or long-term exposure to asbestos increases the risk of inhaling these fibers and developing mesothelioma. However, most patients have experienced exposure at the workplace, with 70 to 80% of patients reporting occupational exposure.