A risk assessment of potential agricultural losses due to ambient SO2 in the central regions of Chile

A risk assessment of the potential impacts of sulphur dioxide (SO2) on the agriculture of central Chile was carried out, using Critical Levels (threshold values above which chronic effects may occur) set by the United Nations Economic Commission for Europe (UNECE, 1993; Sanders et al., 1995), crop sensitivity studies, agricultural land-use data, and air quality data for several years. Ambient SO2 concentrations around three copper smelters in this region were found to pose a significant risk to crops (such as cereals, staples and legumes) on both local and regional scales. Adverse effects on yield, growth and fruit production were considered possible. Frequent high exposure periods during winter months may also give rise to acute injury in sensitive species and/or crops maintained under optimum water conditions. This study identified high-risk areas, where additional monitoring as well as field studies would be beneficial, and has important policy implications, given the secondary SO2 air quality standard currently in force in Chile.