Ozone (O₃), the Other Kind of Oxygen

• Most atmospheric oxygen is in the form of the molecule O₂.  This we require for breathing.
   

• Ozone's chemical behavior is entirely different than that of O₂.
   

• Surface ozone is a serious air pollutant.  It has harmful effects on respiration in humans.  It is produced in several photochemical reactions between hydrocarbons and nitrogen oxides (primary pollutants).
   

• Stratospheric ozone blocks incoming solar shortwave ultraviolet radiation (λ < 320 nm) which is generally harmful to life.  (Ironically, exposure to that same radiation, in small dosages, is beneficial in inducing the body to form vitamin D.)  Some of the benefits of ozone's stratospheric UV absorption are:
  
              1.  Prevention of skin cancer.  It is estimated that for every 1% reduction in
                   stratospheric O₃, the skin cancer rate in humans increases by 2% to 5%.
              2.  Prevention of cataracts and sunburning.
              3.  Prevention of UV-induced damage to human immune systems.
              4.  Prevention of UV-induced damage to crops and animals.
              5.  Prevention of UV-induced reduction in phytoplankton growth.  (Collectively,
                   phytoplankton are even more important than rain forests in liberating O₂
                   from CO₂ via photosynthesis!)