ABSTRACT
Air pollutants have been known for more than one hundred years to affect both yield and quality of agricultural crops. This is true for a wide range of pollutants including sulfur dioxide, fluorides, and nitrogen-containing pollutants such as nitrogen oxides (NO, NO2) and ammonia (NH3). Today, the main focus is on effects of the regional occurrence of elevated tropospheric ozone (O3). In North America and Europe, where emissions of sulfur dioxide and fluorides have declined, the problem of ozone pollution has received the most attention. In contrast, in many developing countries emissions of a number of pollutants are increasing and there are strong indications of adverse effects on crops. However, these effects have been studied to a much lesser extent than in Europe, North America, Japan, and Australia.
