Jayne Leclerc, age 11, of South Windham, Me., for her question:
HOW IS DUST FORMED?
A dust explosion can result from the rapid chemical union of oxygen with clouds of fine, inflammable dust in an enclosed area. Such industrial operations as coal mines and flour mills are in danger of having dust explosions. There have been stories in the news recently regarding this type of accident.
Who isn't bothered by dust? You find it almost everywhere. It is made up of small particles of many different kinds of solid matter. A speck of true dust is smaller than one thousandth of a millimeter. Dust is constantly being formed by almost every type of matter as part of nature's plan.
In the atmosphere, most dust particles are bits of mineral matter that have been picked up by the wind. It can come from plowed fields, mud flats, bare soil and crumbling rocks.
True dust is repeatedly picked up by wind or washed into streams or rivers. Coarser dust settles quickly on the land.
Volcanoes have spread their special kind of dust over much of the world. When a volcano erupts in an explosion, solid lava is changed into powder. Some of the liquid lava forms into tiny drops or slivers of glass which are carried in the air for hundreds of miles.
Condensing water vapor in the atmosphere also can settle on particles of dust to form water droplets. The droplets can unite with others to form either snow or rain. Also, dust in the air acts as a filter to keep some of the sun's rays from reaching the earth.
Dust can be a great problem to workers in factories, mines and quarries. Collected in the lungs of workmen, it has been known to cause a disease called silicosis. In' addition, dust can act as a carrier for disease bacteria. The spore stages of a number of bacteria can be thought of as dust particles themselves and the same is true of both mold spores and the pollens which cause asthma, hay fever and other allergies.
When we think of dust we must certainly think of America's Dust Bowl. This is a section in the southwestern part of the Great Plains where 50 million acres in Texas, New Mexico, Colorado, Kansas and Oklahoma were swept by severe dust storms in the early 1930s. There was a problem with extreme drought conditions coupled with the fact that planted crops did not adequately protect the ground against winds. In 1934 Dust Bowl winds saw great curtains of dust carried all across the continent to the Atlantic coast and far out into the Gulf of Mexico.
During the Dust Bowl winds of the 1930s, it was often impossible to see more than a short distance, and people were forced to wear masks to protect themselves. Drifts of dust sometimes nearly covered farmhouses. Many families were forced to leave the region.
By the late 1930s and early 1940s, adequate amounts of rain solved some of the problems for the Dust Bowl farmers. In the 1950s and mid 1960s, however, below average rains together with high winds again damaged valuable farmland.