Sand and dust storms affect about 330 million people in over 150 countries and are taking an increasing toll on health, economies and the environment, the U.N. World Meteorological Organization says.

“About 2 billion tons of dust are emitted yearly, equivalent to 300 Great Pyramids of Giza” in Egypt, the organization’s U.N. representative, Laura Paterson, told the General Assembly.

More than 80% of the world’s dust comes from the deserts in North Africa and the Middle East, she said, but it has a global impact because the particles can travel hundreds and even thousands of kilometers (miles) across continents and oceans.