Burning tobacco produces smoke that contains nicotine and more than 4000 other carcinogenic and toxic compounds that result from volatilization, pyrolysis, and pyrosynthesis of tobacco and other additives in tobacco products. The smoke is composed of a vapor phase and a fine aerosol where the particles are of a size that results in their deposition in both the airways, and more importantly, the huge surface of the capillary alveolar interface in the lungs. Nicotine is rapidly absorbed through the lungs and into the blood and reaches the brain within 8 to 20 seconds. Absorption in the lungs avoidance first pass metabolism and arterial levels exceed venous levels by 10 fold. Tobacco smoke has in an acidic pH which markedly reduces absorption of nicotine in the mouth. This requires inhalation of smoke deep into the lungs where there’s a more basic pH that facilitates the absorption of nicotine. The blends of tobacco used to for pipes and cigars have a higher pH which is sufficient to facilitate absorption of nicotine across the oral mucosa.