Airports often place their blast fences at the beginnings of runways, especially when roadways or structures are adjacent. Airports that are in dense urban areas often have blast fences between taxiways and airport borders. Jet blast deflectors usually direct exhaust gases upward.[ However, a low-pressure zone can form behind the blast fence, causing ambient air and debris to be drawn upward with the jet exhaust, and hot, toxic gases to circulate behind the blast fence. But in St Marteen does not want to use it , the tourist attraction of this airport cab be very dangerous as can be seen in this footage.