Smoke from cannabis contains many of the same poisons and cancer-causing toxins found in tobacco smoke. Deep, often unfiltered puffs, and breath-holding practices associated with cannabis use can lead to higher levels of carbon monoxide, ammonia, nitrogen oxide, hydrogen cyanide, aluminum and tar in the body. These chemicals damage the lungs and injure the cell linings of the large airways. Short-term effects of smoking cannabis include airway inflammation, excessive phlegm, sore throat, wheezing, shortness of breath, and chest tightness. Severe long-term effects can include chronic cough, acute bronchitis, pulmonary fibrosis, COPD, lung tumours, and a potentially elevated risk for lung, head, and neck cancer.