This document discusses the harmful effects of smoking on the lungs and respiratory system. It begins by describing the healthy respiratory system and shows photos of healthy versus smoker's lungs, demonstrating damage. Smoking damages lung tissues, cilia, and alveoli, reducing the lungs' ability to exchange gases and remove chemicals. Long-term signs of damage include shortness of breath, coughing, infections. Smoking also increases risks of cancer, heart disease, and other health issues. Cigarettes contain over 4000 chemicals including carbon monoxide, arsenic and formaldehyde that cause this damage. Nicotine is highly addictive but quitting can improve health.