Asbestos is the name for several fibrous minerals. The long, thin fibers are strong, and can work well to reduce temperature changes. They are also resistant to fire.
Because of these qualities, people have been using asbestos in products for many years. Asbestos was a favorite of builders and manufacturers during the twentieth century. Some people praised it as a wonder material.
In recent years, however, asbestos has become feared as a threat to human health. Asbestos has been linked to serious health problems, including two kinds of cancer. In some countries, costly repairs were made on many buildings to remove the material. All new uses of asbestos were banned in the United States in two thousand seven.
Still, asbestos develop naturally in rocks and soil in some areas. The material can harm people who do not know it is there.
For more than a century, scientists in California have made maps of rocky areas that might contain asbestos. They did their research on the ground. But scientists are reporting that some asbestos in the earth can now be found quickly by sensing devices from the air.
Gregg Swayze works for the United States Geological Survey in Denver, Colorado. He led the team of scientists. They developed a new method of making maps of hard-to-reach areas. Their test flights took place in two thousand one. A report about the study appeared recently in the publication Geology.
Each kind of mineral has its own structure and chemicals. Fibrous minerals like asbestos are no exception. The light absorbed, or collected, by an asbestos surface can be recognized by an appearance all its own. So can the light that the surface reflects, or reproduces.
Many minerals in the asbestos family can absorb light with a wavelength measuring two-point three micrometers. When the asbestos is seen in light near that wavelength, the minerals look darker than those around them.
The researchers examined areas in the California counties of El Dorado and Plumas from the air. The areas were suspected or known to have rocks and soil containing asbestos. The team’s sensor devices were set on differing wavelengths. The researchers were able to identify asbestos even in places eighty-percent covered by dry grass.
But Mister Swayze notes limits on the asbestos searches from the air. He says water also holds some of the major wavelengths that identify asbestos. For this reason, he says, air searches would need to be done in areas where the climate is dry or plants lacking altogether.
For now, however, the method offers the promise of making a map of asbestos easier and faster than earlier ways.
Recognition of the harm asbestos can do and the ban on its new uses did not take place until recently. But people have suspected it for centuries. More than two thousand years ago, the Roman naturalist Pliny the Elder observed its harmful effects. Pliny and the Greek geographer Strabo both noted that slaves making cloth with the material developed lung problems.