question: Explain the chemical process of combustion in relation to smoking, using exactly 5 placeholders (indicated by underscores) and limiting your explanation to 4 sentences.
answer: Combustion is a chemical reaction that occurs when smoking, involving the burning of tobacco. In this process, oxygen reacts with tobacco components, producing heat, light, and smoke. The smoke contains various substances, including tar, carbon monoxide, and nicotine. These byproducts are inhaled by the smoker, affecting the _, _, and _ systems, while also releasing _ and _ into the environment.