The maximum concentration of vapor that could be attained in the air in a closed space above a liquid at ambient temperature and pressure. If a chemical has a high ambient saturation concentration, it has a strong ability to displace air, and the concentration of the chemical’s vapor in the air above the liquid will be high. If it has a low ambient saturation concentration, the vapor concentration will be low.

This property changes with temperature—a liquid at a higher temperature will have a higher ambient saturation concentration. A chemical that is a gas at ambient temperature and pressure has an ambient saturation concentration of 100% (1,000,000 ppm).