American researchers say dust clouds from dry African deserts may be a threat to human health in the United States. The dust may contain many small organisms that could be dangerous. Each year, huge storms form in the Sahara desert of northern Africa. Winds carry the dust across the Atlantic Ocean. The movement of dust has been increasing in recent years because of longer periods settles in South America. From June to October, the winds change and transport the dust to North America, Central America and the Caribbean. More than half of the dust that reaches the United States settles in the sate of Florida. For many years, it has caused the skies there to turn red. There is probably a link between the dust storms and higher rates of allergies and breathing problems in people in this area.

　　1. human health dust clouds

　　2. the Sahara Atlantic Ocean South America

　　3. October Central America the Caribbean

　　4. the United States Florida the skies

　　5. dust storms allergies breathing problems