text: A pneumatic barrier is a method to contain oil spills. It is also called a bubble curtain. Air bubbling through a perforated pipe causes an upward water flow that slows the spread of oil. It can also be used to stop fish from entering polluted water. A further application of the pneumatic barrier is to decrease the salt-water exchange in navigation locks and prevent salt intrusion in rivers.
  Pneumatic barriers are also known as air curtains.
  The pneumatic barrier is a (non-patented) invention of the Dutch engineer Johan van Veen from around 1940 
  A pneumatic barrier is an active (as opposed to passive) method of waterway oil spill control.  (An example of a passive method would be a containment boom.)