Air stripping towers are vertical cylindrical air stripping devices. They are often used in ground water remediation at sites where gasoline has contaminated ground water. It removes any volatile organic compounds (VOCs) by spraying the water down over whiffle ball-like fill while air flows upward through the water spray. Air stripping towers are packed with gravel or synthetic material. Contaminated water flows downward and air passes upward. This action induces volatile compounds in solution into the vapor phase. If concentrations in air discharging from the top of the column exceed local air quality standards, it may be burned or filtered. Typical air stripping columns are around 7 m tall and 1 m wide.