Smokes

Smoke is the visible aerosol produced by combustion, arising when materials burn incompletely. It is a complex mixture of gases and fine particles whose exact composition depends on the fuel, temperature, and the presence of oxygen and moisture. The gaseous phase typically includes carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide, ammonia, and a variety of volatile organic compounds. The particulate phase comprises soot, tar, ash, and condensed organic compounds such as polycyclic aromatic hydrocarbons. Smoke can be smoky gray, brown, or white, with density influenced by the intensity of combustion and atmospheric conditions.

Common sources of smoke include wildfires, residential heating and cooking with wood or coal, industrial processes, vehicle exhaust, and the burning of tobacco products. Tobacco smoke is a major indoor pollutant and contains thousands of chemicals, including tar, nicotine, and volatile compounds that pose health risks to smokers and bystanders.

Health and environmental impacts are central to smoke discussions. Inhalation can irritate the eyes, throat, and lungs and is linked to respiratory and cardiovascular diseases, cancer, and other health problems. Secondhand smoke affects non-smokers, while thirdhand residues can persist on surfaces. Environmentally, smoke contributes to air pollution, reduces visibility, and can deposit soot on ecosystems and infrastructure. Some components also influence climate through black carbon and other greenhouse gases.

Measurement and regulation typically use metrics such as PM2.5 and PM10 to quantify particulate matter. Regulatory approaches include emission controls for industry, public smoking restrictions, improved combustion technologies, filtration and scrubbers, and measures to reduce exposure in homes and workplaces.

Historically, smoke has served signaling, food preservation, and cultural practices, and remains a focal point of public health and environmental policy.