Ozone was first measured from British Antarctic stations during the International Geophysical Year of 1957/58. It was originally studied because of its influence on the temperature structure of the atmosphere, and also as a tracer for the circulation of stratospheric air. In the 1970s, ozone became the focus of attention as a possible indicator of long-term changes in the atmosphere. Scientists realised that ozone might be affected by the increasing concentration in the atmosphere of man-made gases such as nitric oxide and CFCs. In 1995, Paul Crutzen, Mario Molina and Sherwood Rowland received the Nobel prize for this pioneering work.