What are the three most dangerous substances in tobacco smoke and what effect do they have?

The three most dangerous substances in tobacco smoke are nicotine, tar, and carbon monoxide. Nicotine is highly addictive and can lead to increased heart rate and elevated blood pressure. Tar contains numerous carcinogens that damage lung tissue and contribute to cancer and respiratory diseases. Carbon monoxide reduces oxygen delivery in the body, leading to cardiovascular problems and impaired lung function.