People who smoke (almost 31 million people in the United States) breathe in a mixture of 7,000 chemicals and toxins. Those produce a significant effect on the lungs of people, especially the toxins. The toxins that are inhaled weaken our lungs immunity-wise, which causes our lungs to be readily susceptive to various types of infections. Those infections, in turn, cause the air passages in our lungs to narrow; by that, our air tubes swell and force the air sacs in the lungs to burst like a water balloon. This finally makes the people not to breathe properly and get affected by COPD.

Emphysema is a condition in the lungs that cause people to have shortness of breath. For the people who have this issue, the air sacs in the lungs, known as the alveoli, have gotten damaged. The alveoli are essential to our health because, in these air sacs, the blood cells and the lungs exchange oxygen and carbon dioxide, a process that is vital for our lives for us to live. In the lungs, these air sacs create a small surface area which allows more oxygen-carbon dioxide exchange to occur. However, people with emphysema have the walls of the alveoli weaken and eventually rupture, which creases larger surface area in the lungs and eventually causes the oxygen-carbon dioxide exchange to be very low, which causes the people who have this not to breathe properly and not to live properly. This problem mainly comes to people due to smoking and pollution.

Chronic bronchitis is a type of bronchitis that happens when our bronchial tubes in our lungs have long term inflation and when mucus build up in those tubes. The bronchial tubes in our lungs are really important because these tubes let air go in and out of our lungs as we breathe. However, if these tubes are inflated and have mucus in them, then lower amounts of air is able to pass through in those tubes which cause people to not be able to breathe properly, which leads to COPD in them. This disease is caused primarily due to smoking and some lung diseases (such as astma).