Air in Riccarton Road has a concentration of the cancer-causing toxic chemical benzene that exceeds international standards. An Institute of Environmental Science and Research report, released yesterday, found Christchurch had the highest ambient air benzene concentrations compared with Auckland, Hamilton, Dunedin, and Paeroa. The report was commissioned by the Ministry of Health, New Zealand. The air study, done between July 1996 and June 1997, found the Riccarton Road monitoring site recorded a benzene concentration of 20.1 micrograms per cubic metre of air, exceeding limits in Britain (16 micrograms), the Netherlands (10 micrograms), and the European Union (10 micrograms). The United Kingdom has set an air quality target of 3.2mcg by 2005.