Cigarette tar is the sticky, brown-to-black residue that enters the body when tobacco is smoked. It is not an ingredient intentionally added by manufacturers for flavor or preservation. Tar is simply the byproduct of burning tobacco, a complex mixture of condensed particulate matter generated when the cigarette is lit. The amount of tar measured in a cigarette reflects this condensed residue.
Tar Is a Product of Combustion, Not an Ingredient
The creation of tar is an unavoidable consequence of burning organic material like the tobacco leaf. When a cigarette is ignited, high temperatures—reaching over 900 degrees Celsius—cause the tobacco to undergo combustion and pyrolysis. This intense heat breaks down complex organic molecules into thousands of new chemical compounds.
These newly formed compounds exist as a mixture of hot gases and minute solid and liquid particles, which together form the smoke. As the smoke travels through the unburnt portion of the cigarette and cools, the solid and liquid particles condense. This condensed residue is referred to as tar, often measured as “total particulate matter” excluding water and nicotine.
The Chemical Makeup of Tar
Tar is not a single chemical entity but an extremely complex mixture of over 7,000 different chemical compounds found in tobacco smoke. Many of these compounds are toxic, and at least 70 are classified as carcinogens. The sticky, dark appearance of tar indicates its dense and hazardous composition.
The mixture contains substances such as Polycyclic Aromatic Hydrocarbons (PAHs), which are potent carcinogens resulting from incomplete combustion. Other hazardous components include heavy metals like arsenic, lead, and cadmium. Benzene, a known carcinogen, is also present in the particulate matter that makes up tar.
Biological Effects on the Respiratory System
When tar is inhaled, it deposits a viscous, sticky coating on respiratory tissues. This coating is particularly damaging to the delicate, hair-like structures lining the airways called cilia. Normally, cilia sweep foreign particles and mucus out of the lungs in a process known as mucociliary clearance.
Exposure to tar paralyzes and ultimately destroys these cilia, preventing the lungs from effectively cleaning themselves. This impairment leads to a buildup of mucus and trapped toxins, causing irritation and inflammation. The chronic irritation often results in a persistent cough and is a primary factor in the development of chronic bronchitis, a form of Chronic Obstructive Pulmonary Disease (COPD).
Beyond physical obstruction, the carcinogenic chemicals within the tar directly damage the DNA of lung cells. This genetic damage can initiate the uncontrolled cell growth that leads to lung cancer. The body’s inability to clear the airways, combined with the chemical toxicity, places an immense burden on the respiratory system.
Strategies for Reducing Tar Delivery
Manufacturers and regulators have historically implemented various strategies to reduce the amount of tar delivered to the smoker. The most common method involves the use of filters, typically made of cellulose acetate, which mechanically trap some of the particulate matter. Additionally, many modern cigarettes feature ventilation holes that dilute the smoke stream with outside air, lowering the measured tar yield.
The development of “low-tar” cigarettes relied on these design changes, though health authorities now agree that these products do not significantly reduce the health risk for smokers. More recent strategies focus on entirely eliminating the combustion process that creates tar. Products like heated tobacco systems and vaporizers heat tobacco or liquid without burning it, which drastically reduces or eliminates the formation of solid particulate matter.