In general, you need identification to buy spray paint because it is considered a hazardous material. The aerosignment of spray paint cans is regulated by the Hazardous Materials Regulations (HMR) in order to ensure their safe transportation. Many states and municipalities have additional regulations in place regarding the sale and use of spray paint.
The main reason why ID is required for buying spray paint is because inhalation of its fumes can lead to serious health problems. Some of the ingredients in spray paint, such as xylene and toluene, are volatile organic compounds (VOCs). VOCs are gases that easily become vapors or liquids at room temperature. They can be found in many household products, including cleaning supplies, personal care products, and pesticides. When inhaled, VOCs can cause a variety of short- and long-term health effects, such as eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment. Inhalation of high levels of VOCs can also damage the liver, kidney, and central nervous system and increase the risk of cancer.