Formaldehyde is a colorless gas with a pungent smell, widely used in manufacturing building materials, household products, and some cosmetics. It is also naturally produced in small amounts by the human body during normal metabolic processes. In indoor environments, it can be released from pressed wood products, glues, and certain fabrics. Health organizations recommend minimizing exposure through proper ventilation and choosing low-emission products. While high concentrations may cause irritation to the eyes, nose, or throat, regulated use and modern manufacturing standards have significantly reduced risks in everyday settings. Formaldehyde is not used in food or personal care items intended for direct ingestion or prolonged skin contact without safety controls.