Secondhand smoke, also known as environmental tobacco smoke, is the combination of smoke from a burning tobacco product and the smoke exhaled by a smoker. It is a recognized public health concern because it is involuntarily inhaled by individuals other than the active smoker. This exposure can occur in various settings, including homes, workplaces, and public areas.
Composition of Secondhand Smoke
Secondhand smoke is a complex mixture of chemicals consisting of two types of smoke: sidestream and mainstream. Sidestream smoke emanates directly from the lit end of a tobacco product, while mainstream smoke is what a smoker inhales and then exhales.
About 85% of secondhand smoke is sidestream smoke. This type is more hazardous because it is generated at lower temperatures, resulting in incomplete combustion. This process creates higher concentrations of harmful chemicals and cancer-causing agents compared to mainstream smoke.
This toxic mixture contains over 7,000 chemical compounds, with at least 70 identified as carcinogens. Among the most recognized substances are benzene, a chemical found in gasoline; formaldehyde, an industrial chemical used for preservation; and carbon monoxide, a poisonous gas found in car exhaust.
Health Consequences
Exposure to secondhand smoke has serious health implications for non-smoking adults, directly impacting cardiovascular health and increasing the risk of heart disease and stroke. For individuals with existing heart conditions, the exposure is especially dangerous. It is a confirmed cause of lung cancer in people who have never smoked, and there is evidence suggesting a link to other cancers of the larynx and throat.
Children are vulnerable to secondhand smoke due to their developing bodies and higher breathing rates. For children, exposure increases the risk of Sudden Infant Death Syndrome (SIDS). It is also a cause of respiratory illnesses, leading to more frequent and severe asthma attacks, bronchitis, and pneumonia. Ear infections are another common ailment in children exposed to tobacco smoke.
Pregnant women and their developing fetuses face specific risks from secondhand smoke. Exposure during pregnancy can lead to complications like low birth weight, which has lasting effects on a child’s health. The chemicals from the smoke cross the placenta and directly affect the unborn baby.
Distinguishing Thirdhand Smoke
Thirdhand smoke refers to the chemical residue from tobacco smoke that adheres to surfaces and dust after the smoke has cleared. These toxic particles can cling to hair, clothing, furniture, carpets, and walls for months. Over time, this residue builds up and creates a long-term source of indoor pollution.
Thirdhand smoke differs from secondhand smoke in its persistence and transformation. Exposure occurs through skin contact, ingestion of contaminated dust, or inhalation of gases released from settled particles. The chemicals in the residue can react with common indoor pollutants, like nitrous acid, to form new cancer-causing compounds known as tobacco-specific nitrosamines.
Methods for Exposure Prevention
The most effective way to protect non-smokers is the creation of completely smoke-free environments, as there is no risk-free level of exposure. Measures such as separating smokers, using air cleaners, or opening windows are not sufficient to eliminate the risks. These methods do not remove all the harmful particles from the air.
Implementing smoke-free rules for your home and vehicle is a direct way to protect your family. Supporting and advocating for comprehensive smoke-free laws in public places, such as workplaces, restaurants, and parks, extends this protection to the wider community.
Smoke-free policies are the only proven way to protect individuals from both secondhand and thirdhand smoke. Education and public awareness campaigns also help inform people about the risks and encourage the adoption of these policies.