Environmental Tobacco Smoke (ETS), also known as secondhand smoke, is a mixture of the smoke exhaled by smokers and the smoke emitted from the burning end of a cigarette, cigar, or pipe. It contains thousands of chemicals, many of which are toxic and can cause serious health issues. People who do not smoke but are exposed to ETS can still suffer from its harmful effects. ETS is particularly concerning in enclosed spaces, where it can accumulate and affect non-smokers, including children and pregnant women. Exposure to ETS has been linked to respiratory problems, heart disease, and increased risk of lung cancer. Reducing exposure to ETS is important for public health and well-being.