We thank Mr Denny Sim for his views (Rein in pollution from developments on Jurong Island, May 13).

Singapore meets the World Health Organisation's (WHO) ambient air quality guidelines for nitrogen dioxide. For example, the 2019 average nitrogen dioxide level of 23 ug/m3 is well below the WHO guideline of 40 ug/m3. In Singapore, industries and vehicles are the main sources of nitrogen dioxide emissions.

The National Environment Agency (NEA) has implemented a suite of measures to reduce the emission from these sources, including the tightening of emission standards for both new and existing industrial plants, introduction of stricter standards for fuel quality, and tighter emission standards for new vehicles.

We also have incentive schemes to encourage the turnover of older, more pollutive vehicles.

When the Economic Development Board (EDB) brings in potential investors for projects on Jurong Island, NEA informs these investors of Singapore's pollution control requirements in advance. A process of licensing and inspection ensures that mitigation measures that meet our requirements are in place.

Major emitters are required to install stack emission monitoring systems to provide NEA with real-time monitoring of pollutant emissions. EDB, NEA and JTC Corporation will continue to work closely with companies on Jurong Island to ensure that economic development is pursued together with a strong focus on environmental sustainability.

Cheang Kok Chung

Director, Pollution Control Department

National Environment Agency