Exterior paint should never be used indoors. It contains volatile organic compounds, or VOCs, fungicides and other additives that are harmful indoors. These additives make exterior paint resistant to dirt, mildew and damage caused by ultraviolet rays and environmental factors.
The VOCs in paint evaporate at room temperature and degrade indoor air quality. Prolonged exposure to high VOC levels can cause serious health problems, including liver damage. Federal guidelines require that interior paints contain low or zero VOCs. Low-VOC latex paints cannot exceed 250 grams of VOCs per liter, and low-VOC oil-based paints cannot exceed 380 grams of VOCs per liter. There are paints that are formulated for both indoor and outdoor use, but they are usually marked “interior/exterior” on the can.