We ascertain the risk level of every environmental aspect identified for significance, based on criteria such as legal requirement, severity of environmental impacts and  the likelihood of occurrence (taking into account the frequency of aspects occurring and existing control measures) to finally arrive at the risk level. The risk level for each environmental aspect is determined based on a severity- likelihood matrix and is used to determine whether a particular aspect is entered into the Significant Environmental Aspect Register. We then develop actions plans to control or mitigate each significant environmental impact based on the risk level of the corresponding environmental aspect, taking into consideration other factors such as the feasibility of control/mitigation measures as well as operational, financial and technological constraints. 

The GRI environmental indicators were chosen from the Significant Environmental Aspect Register (except of ozone-depleting substances which is insignificant in quantity) to comprehensively cover air, land and water elements.

For air pollutants, SO₂, CO₂ and hydrochlorofluorocarbons were chosen because these are the major air emissions arising from the business operations, and the latter two in particular were chosen due to their association with climate change.

For water pollutants, we have included the major compliance-related pollutants such as biological oxygen demand and chemical oxygen demand which are bounded by law, as well as oil-spill incidence. We have also included water consumption arising from our business operations in the context of Singapore’s focus on water self-sufficiency.

For land pollutants, we have included hazardous and non-hazardous wastes as there is a fair proportion of the former which is treated and shipped internationally under the Basel Convention.