Ozone

Ozone measurements are given in Dobson units and are integers with 3 significant figures. A Dobson Unit represents the physical thickness of the ozone layer if it were brought to the earth's surface. A value of 300 Dobson units equals three millimeters.

Ozone A nearly colorless (but faintly blue) gaseous form of oxygen, with a characteristic odor like chlorine. Its formula is O3; its molecular weight is 48. Ozone is found in trace quantities in the Earth's atmosphere at all times, primarily in the stratosphere between heights of about 10 and 50 km (the ozonosphere or ozone shield) where its production results from photochemical processes involving ultraviolet radiation. Its maximum concentration occurs between 20 and 25 km. In the lower atmosphere, ozone is commonly formed as a product of electrical discharges through the air.

Tropospheric ozone (ground-level ozone), or smog, is formed when volatile organic compounds, oxygen and nitrogen oxides react in the presence of sunlight. Ground-level ozone is a pollutant and a respiratory irritant. Stratospheric ozone occurs in the upper atmosphere an protects the earth from the sun´s ultraviolet rays.

A compound that is formed when oxygen and other compounds react in sunlight. In the upper atmosphere, ozone protects the earth from the sun's ultraviolet rays. Though beneficial in the upper atmosphere, at ground level, ozone is called photochemical smog, and is a respiratory irritant and considered a pollutant.

A form of oxygen, O₃. A powerful oxidizing agent that is considered a pollutant in the lower troposphere but an essential chemical in the stratosphere where it protects the earth from high-energy ultraviolet radiation from the sun.