A recent study reveals that smoking alters the body's immune system, rendering individuals susceptible to diseases and infections even after quitting. Despite declining smoking rates, it remains the leading cause of preventable death in the US, claiming over 480,000 lives annually. The research underscores the importance of quitting smoking, as it impacts immune response significantly and may increase the risk of chronic diseases associated with inflammation. While quitting improves immune response, full recovery takes years, emphasizing the urgency of cessation efforts regardless of smoking intensity.