The biggest hazards of long-term smoking are the following: first, lesions in the lungs, which can lead to chronic bronchitis, chronic obstructive pulmonary emphysema, and even cause pulmonary heart disease and lung cancer. Second, long-term smoking can cause damage to the heart, which can appear faster heartbeat and higher blood pressure. Third, it can cause changes in the digestive tract, causing gastritis, gastric ulcers, and even induce the occurrence of gastric cancer. Fourth, it can cause changes in the oral cavity, especially yellow and black spots on the teeth, bad breath, oral cancer, and tongue cancer.