MONITORING BENZENE IN AMBIENT AIR

Dr Kanwaljit Soin asked the Minister for the Environment (a) what is the level of benzene concentration in the air in Singapore; (b) whether there is any monitoring of the level of that concentration; and (c) what is the permissible limit.

Mr Mah Bow Tan: (a) Benzene is a suspected carcinogen. Diseases of the blood such as leukaemia and anaemia have in other countries been associated with repeated exposure to high concentrations of benzene vapour in the workplace.

(b) Monitoring of benzene in ambient air was initiated by my Ministry in 1990. So far, benzene has not been detected in our air.

(c) The main source of benzene in ambient air is potentially from automotive petrol. Benzene is naturally present in petrol and may even be added as an octane booster. Complete combustion in the petrol engine converts the benzene to harmless products. To ensure it does not pose a problem, the level of benzene in petrol used in Singapore is closely monitored by my Ministry.

(d) There are currently no standards or guidelines prescribed for benzene in ambient air although there are standards for workplace exposure. The Department of Industrial Health adopts a maximum permissible limit of 5 parts per million for workplace exposure for a normal 8-hour workday and a 40-hour workweek.