Mesothelioma is known only to be caused by asbestos exposure. Asbestos is a nature, yet toxic mineral that was used commonly in heavy industry. Microscopic asbestos fibers enter the body through the lung or ingestion. Once inside, the durable fibers are unable to be broken down or expelled by the body, causing a harmful inflammation and scarring of the mesothelium. This scarring lays the groundwork for malignant mesothelioma and other respiratory conditions, such as asbestosis.

There is a great deal of latency associated with asbestos exposure and the onset of mesothelioma. Often patients will not encounter mesothelioma symptoms until 30-50 years following exposure to asbestos. In many cases, those diagnosed with mesothelioma are not those who were directly exposed to asbestos in a jobsite setting. Spouses and children of those exposed to asbestos who frequently came into contact with the fibers on the clothing or person of those exposed have also developed malignant mesothelioma as a result.