Ozone vacuum-ultraviolet (VUV) ozone generators, employ a light source that generates a narrow-band ultraviolet light, a subset of that produced by the Sun. The Sun's UV sustains the ozone layer in the stratosphere of Earth. UV ozone generators use ambient air for ozone production, no air prep systems are used (air dryer or oxygen concentrator), therefore these generators tend to be less expensive. However UV ozone generators usually produce ozone with a concentration of about 0.5% or lower which limits the potential ozone production rate. Another disadvantage of this method is that it requires the ambient air (oxygen) to be exposed
History of the Berlin S-Bahn that were left opened after the strike do include: The 1980 incidents turned media and political attention toward what was left of West Berlin's S-Bahn network. The city government decided to enter negotiations with East Germany, which were finally successful. By contrast, during the same period, services on the S-Bahn in East Berlin were increased and new lines built as housing projects expanded eastward from the city centre. With most of the U-Bahn located in West Berlin, the S-Bahn became the backbone of the East Berlin transit network. The DR has purchased DR Class 270 as a result, where it