THERE are a few standard procedures to tackle oil spills. They can be contained by booms (inflatable lengths of rubber that float around an oil spill) and collected by using oil skimmers. Or, they can be dissipated by spraying chemicals called dispersants on a spill. The chemical emulsifies the oil so it is easily attacked by micro-organisms and the natural process of weathering spilt crude oil is accelerated.

But dispersants have to be used cautiously. They are generally not recommended for coastal oil spills or in water less than 60 m deep. They can be used, however, in the open sea because the currents will disperse them. Says C K Varshney, dean of the School of Environmental Sciences at the Jawaharlal Nehru University, "Dispersants break up the oil layer, which would otherwise block light and air from getting through to marine organisms. But, being chemicals, they are harmful as well. Their use in this (Maersk Navigator) case was the lesser of two evils."