The Sahara is the major source on Earth of mineral dust (60-200 millions of tons per year). Saharan dust can be lifted by convection over hot desertic areas, and can thus reach very high altitudes; from there it can be transported worldwide by winds, covering distances of thousands of kilometers. The dust combined with the hot dry air of the Sahara Desert often forms an atmospheric layer called the Saharan Air Layer which has significant effects on tropical weather, especially as it interferes with the development of hurricanes. There is a large variability in the dust transport across the Atlantic into the Caribbean and Florida from year to year. Due to the trade winds, very large concentrations of mineral dust can be found in the tropical Atlantic, reaching the Caribbean; moreover episodic transport to the Mediterranean region as well as Northern Europe is observed. In the Mediterranean region, Saharan dust is important as it represents the major source of nutrients for phytoplankton and other aquatic organisms. Saharan dust carries the fungus Aspergillus sydowii which falls into the Caribbean Sea and possibly infects coral reefs with Sea Fan disease (aspergillosis). It also has been linked to increased incidence of pediatric asthma attacks in the Caribbean. Since 1970, dust outbreaks have worsened due to periods of drought in Africa. Dust events have been linked to a decline in the health of coral reefs across the Caribbean and Florida, primarily since the 1970s.
It is known that one the major factors that create hurricanes is warm water temperatures on the surface of the ocean. One theory holds that dust from the Sahara desert caused surface temperatures to be cooler in 2006 than in 2005. Evidence shows that surface temperatures dropped by one third because of the Subsaharan dust.
In Eastern Asia, mineral dust events originated in springtime in the Gobi Desert (Southern Mongolia and Northern China) gives rise to the phenomenon called Asian dust. The aerosols are carried eastward by prevailing winds, and pass over China, Korea, and Japan. Sometimes, significant concentrations of dust can be carried as far as the Western United States. Areas affected by Asian dust experience decreased visibility and health problems, such as sore throat and respiratory difficulties. The effects of Asian dust, however, are not strictly negative, as it is thought that its deposition enrichs the soil with important trace minerals. An American study analyzing the composition of Asian dust events reaching Colorado associates them to the presence of carbon monoxide, possibly incorporated in the air mass as it passes over industrialized regions in Asia. Although dust storms in the Gobi desert have occurred from time to time throughout history, they became a pronounced problem in the second half of the 20th century due to intensified agricultural pressure and desertification.