Ozone (O3) is well documented as the air pollutant most damaging to agricultural crops and other plants. Most crops in developed countries are grown in summer when O3 concentrations are elevated and frequently are sufficiently high to reduce yields. This article examines the difficulties in scientifically determining the reduction in yield that results from the exposure of agricultural crops to surface O3 and then transforming that knowledge into efficient and effective regulatory standards. The different approaches taken by the United States and Europe in addressing this issue as well as the few studies that have been conducted to date in developing countries are examined and summarized
