The Effects of Ozone on the Stratosphere & Troposphere

The oxygen that people breathe is known as dioxygen. Comprised of two oxygen atoms, dioxygen is described by the molecular formula O2. Although ozone is made of the same element (an allotrope), it carries an additional oxygen atom, and therefore has the formula O3. A bluish gas with a pungent odor, ozone is usually found in high concentrations in the stratosphere (upper atmosphere) and in modest concentrations in the troposphere (lower atmosphere), reports Science Clarified.

Ozone in Stratosphere and Troposphere

• In comparison to ozone in the troposphere, naturally occurring ozone in the stratosphere (eight to 30 miles from Earth) not only exhibits different behavior but also has a different function. Stratospheric ozone molecules are split by the sun's ultraviolet rays. The resulting single-atom oxygen molecules are highly reactive and combine with O2 to form O3. Because this ozone absorbs most of the shortwave UV radiation, it serves as Earth's buffer from dangerous solar radiation, according to the Encyclopedia of Earth.

  In the troposphere (zero to eight miles from Earth), the temperature declines due to lower pressures of atmospheric gases as well as reduced transport of heat from the planet's surface. Solar radiation that strikes the Earth bounces back up into the troposphere where turbulence redistributes the ultraviolet rays. Hydrocarbons released by soil and plants and meager amounts of stratospheric ozone comprise the sources of naturally occurring ozone in the troposphere.

Ozone Hole

• In 1985, a British Meteorological Survey team discovered that ozone concentrations over Antarctica had plummeted by about 40 percent between 1977 and 1984, when compared to 1960 levels. This ozone hole represented the first clear-cut evidence that human activities are affecting the environment. The chlorofluorocarbons (CFCs) used in refrigerants, spray cans and other manufactured products are neither toxic nor flammable. However, these compounds rise into the stratosphere and are then broken down by radiation into chlorine atoms. In the upper atmosphere, free chlorine atoms can annihilate tens of thousands of ozone molecules, thus destroying the Earth's shield from the sun.

  While the 1987 Montreal Protocol led to an international effort to eliminate chlorofluorocarbons, the effects of these compounds on the stratosphere can last 100 years, reports the Center for International Earth Science Information Network. The increase in UV radiation can lead to various health issues, including premature aging, skin cancer, cataracts and damage to the human immune system.

Ozone Pollution

• In contrast to the stratosphere where ozone plays a protective role, ozone functions as a greenhouse gas in the troposphere. Generated by the chemical reaction between nitrogen oxide emissions from industry and vehicles and hydrocarbons, ozone is a major element of smog. As an irritant to the lungs akin to cigarette smoke, ozone causes an increased susceptibility to infections, asthma, emphysema and other respiratory ailments, according to the Center for International Earth Science Information Network. As well, the undersides of plants (stomata) shut down due to high levels of ozone, retarding photosynthesis and growth. The ozone effects on agriculture may adversely impact the world's food supply.