Thomas Cahill, an international authority on the constituents and transport of airborne particles, has studied air-quality emergencies around the world including the fallout from the Kuwaiti oil fires of 1991. Cahill can discuss his studies from those fires, including estimates of the amount of soot produced by the hundreds of burning wells; findings of biologically dangerous metals (vanadium, nickel, mercury and molybdenum) in Kuwaiti oil at much higher concentrations than had been expected; and the effects of local conditions such as sand storms on the dispersal of oily smoke. In the 1991 Gulf War, Cahill's research group took air samples at the behest of the Kuwaiti Ministry of the Environment. The group is not monitoring air quality in this conflict. Cahill is a professor emeritus of physics and atmospheric sciences and a research professor in applied science and heads the UC Davis DELTA Group (for Detection and Evaluation of Long-range Transport of Aerosols), a collaborative association of aerosol scientists at several universities and national laboratories. DELTA Group has studied the airborne particles released from the 2001 collapse and fire of the World Trade Center; the eruption of Mount St. Helens, Oregon; Arctic haze from Siberia; and annual dust storms from Africa and Asia.