Definition: Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
Input: Context: Can storms in Africa cause asthma in the Caribbean ? Islanders point to the desert insects that land on beaches after a 5,000-kilometer flight across the Atlantic. If they can use winds to get from one continent to another, so can clouds of dust that carry disease. Scientists think that as Africa becomes drier, dust from expanding deserts is being blown away into Caribbean islands. A study in Barbados shows that asthma has increased 17 times since Africa's drought began in 1973. Other forms of life are suffering, too. Among them are the Caribbean's famous coral reefs( ), which began dying in large numbers in the 1900s. Eugene Shinn of the U.S. Geiological Sudrvey(USGS) in Florida went to the virgin Islands to study the reefs. The tests he and his colleagues carried out showed that the coral was dying of disease caused by Africa microbes from across the ocean. William Sprigg of the University of Arizona is studying the problem as part of a major UN project. He says that dust is causing problems in the U.S., too. "We are just beginning to collect the evidence of airborne dust influences on human health," he toldThe Washington Post. 
 Question: Where does the dust talked about in this passage come from?
Output:
africa.