• Many homes built from the 1930s through the 1970s in Canada and in the United States have asbestos siding. If it is in good condition, there is no hazard. However, if it is cracked, damaged or crumbly, or if a homeowner wants to remodel or remove it, then the siding poses a potential health hazard. When removed, the asbestos fibers or dust are released into the air, where they are breathed in and do damage to the lungs.
  
  

Asbestos Fibers and Dust

• Asbestos siding weakened by "heat, water, weathering or aging" can become "friable," which means hand pressure can break it up, according to the Minnesota Department of Health. Once broken up, it can release asbestos fibers or dust into the air. Once airborne, asbestos fibers or dust can be inhaled. In addition, sanding, sawing, scraping or drilling holes into asbestos siding can release asbestos fibers or dust into the air, as can vacuuming or sweeping up broken pieces of asbestos siding or its dust, according to the U.S. Environmental Protection Agency. However, symptoms of the diseases caused by inhaling asbestos dust or fibers usually do not show up for 20 to 30 years after exposure.
  
  

Asbestosis

• Asbestosis is one of three diseases associated with breathing in airborne asbestos fibers or dust. Inhaling asbestos fibers causes lung scarring because it irritates lung tissue. Asbestosis is a non-cancerous, chronic and serious respiratory disease. "Symptoms of asbestosis include shortness of breath and a dry, crackling sound in the lungs while inhaling," according to Princeton University.
  
  

Mesothelioma

• Mesothelioma is a rare form of cancer that attacks the lining of the chest or abdominal cavity, according to Health Canada. Inhaling asbestos fibers causes virtually all cases of mesothelioma.
  
  

Lung Cancer

• The risk of lung cancer from inhaling asbestos fibers "increases with the number of fibers inhaled" and "is also greater if you smoke," according to the EPA. Common symptoms of lung cancer include coughing, shortness of breath, chest pains and anemia.