Surprise: High Ozone Levels in Mountains of Tibet

In addition to thin air and sub-zero temperatures, climbers scaling Mount Everest face another challenge. Mountains in the Tibetan plateau where Everest is located contains levels of ozone as high as that of heavily polluted cities.

"Around the circumference of Tibet, there's a halo of very high levels of ozone," said Kent Moore, a physicist at the University of Toronto and lead author of a new report on the discovery.

Ozone is a colorless and highly corrosive molecule. It's made up of three oxygen atoms instead of the usual two that are crucial to breathable air.

Most of the Earth's ozone is found in the stratosphere, from about 8 to 30 miles above the planet's surface. Mount Everest is 5.5 miles high at its peak.

Ozone in the stratosphere helps protect the globe from the Sun's ultraviolet rays. But closer to the ground, where it is produced when auto emissions and other pollutants interact with sunlight, ozone is a major component of smog.

If inhaled, ozone can cause coughing, chest pain and damage to the lining in the lungs.

Surprise: High Ozone Levels in Mountains of Tibet