Volatile organic compounds are certainly something you should minimize, and paint manufacturers are working toward lowering their levels all the time. VOCs release into the air while you’re painting, and when painting indoors they can give you a headache if you aren’t wearing a respirator or haven’t ventilated the room properly. Some VOCs have been identified as carcinogens, and the EPA now sets legal limits on them. For any house paint (interior or exterior) to be called “low VOC,” there is a maximum number of grams per liter of VOCs the paint may contain. For water-based paint, that number is 250; for oil-based paint, that number is 380. Many are much lower. Paints are considered VOC-free if they have less than 5 grams per liter. Currently, these paints are quite difficult to find and expensive.