Hole in the 'Zone

What's Going On Up There?

The Earth's protective ozone layer is getting thinner. There's less ozone to absorb harmful radiation from the sun, and more of this radiation is reaching the Earth's surface. This affects our atmosphere—and our health.

Troposphere: This thick, dense layer is closest to Earth. It contains the air we breathe and is where most weather takes place.

Stratosphere: This is home to the protective ozone layer.

Mesosphere: Ions in this layer act like a mirror, reflecting certain radio signals back to Earth.

Thermosphere: Very few air molecules make it all the way up to this top layer. So it's hard to tell where the atmosphere ends and outer space begins.

Learn more at NASA's Liftoff to Space Exploration site.

  Click to enlarge image
Ozone creation. Source: NASA
Ozone forms when an oxygen molecule gains a third oxygen atom.
Source: NASA: Ozone and the Atmosphere

Ozone is a form of oxygen. It generally forms when oxygen (O2) from near the Earth's surface drifts high up into the atmosphere. Ultraviolet (UV) radiation from the sun hits the oxygen molecules.

Some molecules split apart, creating single atoms. These atoms sometimes link up with O2 molecules, forming a new molecule with three oxygen atoms. That's ozone (O3).

Ozone can be helpful or harmful, depending on where it's located. If it's high up, it's good ozone. Ozone in the stratosphere protects people, animals, and plants from harmful ultraviolet rays.

In 1985 scientists found a large ozone hole in the stratosphere over Antarctica. Each year the hole became bigger, letting more ultraviolet light through to the Earth's surface. This situation is called stratospheric ozone depletion (SOD). Without the protection provided by ozone, we face a number of health problems.


Ozone high in the stratosphere is good, but ozone near the ground is not. Do you ever hear "ozone warnings" on the weather report? Ozone can be very unhealthy.


Inhaling ozone can damage the respiratory tract, which enables us to breathe. Ozone also stunts plant growth. That hurts farmers, agriculture, and our economy.


health_iconHow does ozone protect us?

science_iconWhat's a "hot spot"?


Hole in the 'Zone Home back_holenext_hole What's eating our ozone?

Additional information