Atmospheric Environment 35 (2001) 4903–4915 A risk assessment of potential agricultural losses due to ambient SO 2 in the central regions of Chile T. Garcia-Huidobro a, *, F.M. Marshall b , J.N.B. Bell b a National Commission for the Environment (CONAMA) Obispo Donoso No. 6, Providencia, Santiago, Chile b Imperial College Centre for Environmental Technology, T.H. Huxley School of the Environment, Earth Sciences & Engineering, Imperial College at Silwood Park, Ascot, Berkshire, SL5 7PY, UK Received 1 September 2000; received in revised form 20 May 2001; accepted 6 June 2001 Abstract A risk assessment of the potential impacts of sulphur dioxide (SO 2 ) 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 SO 2 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 SO 2 air quality standard currently in force in Chile. r 2001 Elsevier Science Ltd. All rights reserved. Keywords: Air pollutants; Agriculture; Chile; Yield; SO 2 1. Introduction Major advances have been made in recent years in elucidating the effects of air-borne pollutants on crops and forest trees, yet many of the developing countries of Africa, Asia and Latin America remain little aware of these risks. Chile is one such country, where rapid industrialisation and urbanisation, and a growing demand for energy and transport, have been accom- panied by a strong increase in air pollution. Santiago City has been listed as one of the 4 most polluted cities in Latin America (Romieu et al., 1991). The study of air pollution in Chile has centred mostly on human health effects and the impacts of particulate matter (PM) in Santiago City (Aranda et al., 1994; Ostro et al., 1996; Ilabaca et al., 1999), and to a lesser extent, on the adverse effects of sulphur dioxide (SO 2 ) around large copper smelters. Chile is the world’s largest producer of primary copper, and also the largest exporter of table grapes in the Southern Hemisphere, and conse- quently depends strongly on its mining and agricultural exports. The mining industry (40–50% of exports) constitutes the most significant source of ambient SO 2 in the central regions of Chile (Gallardo et al., 2000). Notably, much of the country’s agricultural production takes place in the same regions, where a Mediterranean climate prevails (321–351S) and where a wide variety of crops are grown, with fruit products grown for export and traditional cultivars, such as wheat and potato, destined mostly for internal consumption. Despite the potential conflict between urban and industrial expansion, and the sustainability of the agricultural sector, no research has been carried out into the impacts of air pollution on Chilean crop varieties. Conversely, many studies have been carried out in industrialised countries over the last *Corresponding author. E-mail address: tghuidobro@conama.cl (T. Garcia-Huidobro). 1352-2310/01/-see front matter r 2001 Elsevier Science Ltd. All rights reserved. PII:S1352-2310(01)00344-2