Nine Dobson spectrophotometers from Algeria, Botswana, Egypt, Kenya, Nigeria, Seychelles and South Africa were sent to Dahab, Egypt, for intercomparison under the leadership of the Egyptian Meteorological Agency. External experts from the United States National Oceanic and Atmospheric Administration, the German Weather Service and the Czech Hydrometeorological Institute participated. Eight of the nine instruments were calibrated and made capable of measuring total ozone with better than 1 per cent accuracy, while one instrument was sent to Germany for repair and calibration before being returned to service.