Inhaling chemicals causes mutations within the body and those mutations how cancer can start. The death rate fell by 2.8%—from 49.4 per 100,000 in 2017 to 48.0 in 2018. Tobacco is the leading cause of preventable death in the United States. Tobacco smoking is the single most important preventable cause of ill health and death in Australia. Vaping Is Less Harmful Than Smoking, but It’s Still Not Safe. 1 in 10 of smoked cigarettes is illicit. Smoking causes cancer, heart disease, stroke, lung diseases, diabetes, and chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis. 2.