Due to all these facts and the heavy industries along the shoreline, airborne and marine pollution are serious problems in the area. Environmental groups have raised concerns about the risks of oil spills and other types of pollution, particularly in the light of the bay's ecological importance. In May 1998, an accident at the Acerinox plant in Los Barrios, caused the release of a radioactive cloud. The radiation was not detected on site, but was eventually detected in France, Italy, Switzerland, Germany, and Austria. The radioactive levels measured were up to 142 times higher than normal. Due to the large number of ships that transit the strait, there is always a danger of accidents and in recent years there have been a small number of sinkings, groundings and collisions in both Gibraltar and Spain resulting in oil spills ("New Flame", "Spa Bunker IV", "Samothraki", "Sierra Nava", "Tawe" and "Fedra").