Smoking is not a direct cause of tuberculosis; smoking can cause lung cancer. Tuberculosis is caused by infected Mycobacterium tuberculosis, and TB patients with bacteria in their sputum are the main source of infection. TB patients can spread microscopic droplets of Mycobacterium tuberculosis into the air by coughing, sneezing, talking and laughing, which can survive in the air for several hours and can be infected by others after being inhaled. Therefore, it is important to keep a certain distance from TB patients and to wear a mask to prevent infection. Tuberculosis patients should also cover their mouths and noses when coughing or sneezing to avoid spreading the germs into the air and infecting others. Tuberculosis patients should not spit or go to crowded places, and if they must go, they should wear a mask to avoid spreading the germs into the air.