Not coughing after quitting smoking is not necessarily a good sign, because tobacco contains many substances that are harmful to the body, such as benzo(a)pyrene, tar, nicotine and some other soot, which itself is damaging to the respiratory tract. In the repeated stimulation of damage may lead to the respiratory tract and the lungs deposited a lot of garbage, resulting in a decrease in sensitivity, so there is some stimulation of the outside world, but not as normal as the exposure to these stimuli after the obvious reaction, this obvious reaction is actually a protection for the body, can be timely to the dirty things out. However, the ability of smokers to do this decreases, so they can’t get rid of the garbage, including the smoke they inhale, which may be deposited in the lungs and cause some hyperplasia or other mutations in the lungs, such as interstitial lung diseases and lung tumors, which may be related to the deposition of this garbage in the lungs, so not coughing after quitting smoking is not a good sign.