Ground Level Ozone Pollution in Africa and Tropical Crop Plants

1. Background to the problem Ozone (O3) is a gas that occurs naturally in the air. However, additional ground level ozone forms when pollutants from human activities react together in the presence of sunlight. Activities include vehicle use, industry and biomass burning. Ozone concentrations can be particularly high in agricultural areas downwind of large cities. Certain weather conditions (stable air mass, prolonged dry spells) and high levels of air pollution can lead to “ozone episodes.” Episodes are when ozone concentrations peak for several days at a time. Ozone is a hidden threat when mixed with air because we cannot taste, smell, or see it.