Chemicals in cigarette smoke affect the entire body. This is why smoking causes so many diseases, including a dozen types of cancer, heart disease and various lung diseases. As soon as you take a puff on a cigarette or breathe in someone else’s smoke, poisonous gases like formaldehyde will start to irritate your eyes, nose and throat.
Your lungs and airways
When you inhale the smoke, it damages the tissues of your airways and lungs. Chemicals like nitrogen oxide can constrict your airways, forcing your lungs to do more work and making breathing more difficult. Hydrogen cyanide, carbon monoxide and ammonia weaken the natural cleaning mechanisms that clear your lungs and airways of toxins. This means that other dangerous chemicals, bacteria and viruses that you inhale stay inside your lungs. Radioactive polonium-210 becomes deposited at the points where your airways split to connect to your lungs. This can subject local cells to much more radiation than they would otherwise experience. From the lungs, cancer-causing chemicals and other poisons in tobacco smoke are absorbed into your bloodstream. These poisons are then carried to other parts of your body.
Your heart and blood vessels
Many tobacco poisons such as arsenic and hydrogen cyanide can directly damage the cells that line your heart and its blood vessels. Nicotine and carbon monoxide cause blood vessels to constrict. Smoke also increases your level of blood cholesterol and as a result, raises your chances of developing a blood clot. Gases such as carbon monoxide and nitrogen oxide reduce your blood’s ability to transport oxygen. This lowers the amount of oxygen reaching your brain and other organs and reduces your energy levels.