Dust in the wind
Everybody in Hong Kong knows about dust storms because they are starting to affect us. Dust storms happen all over the world, not just on the mainland. Some of the worst ones ever seen happened in the 1930s in the United States, where large areas of farmland became a dust bowl.
But the ones that have been affecting us recently started in the Gobi desert, which is on the border region of China and Mongolia. At more than 1,600 kilometres long, it is the biggest desert in Asia and the fifth biggest in the world. In spring, strong winds whip across the desert. The winds can get up to more than 90km/h, picking up dust and sand. In four to six days, they can even reach the US and cause a haze there.
The growing desert
The Gobi has been causing dust storms for a long time. But the problem is getting worse now. The scary thing is that the Gobi is growing very fast. Scientists think the desert is eating up grasslands at around 3,600 sq km a year.
This is called 'desertification'. That is when land that can be used for farming gets swallowed by desert. This is mainly caused by trees being cut down for firewood or other purposes. The central government has launched tree-planting campaigns, but it's difficult to stop a desert on the move. In the meantime, dust storms continue to become a bigger headache for Beijing - and Korea, Japan, Taiwan and Hong Kong - every year.
