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    Mar 12, 2014

    More 'moderate' days under revised PSI

    FROM May this year, Singapore will get a new air-quality reporting index, which incorporates PM2.5 into the current Pollutant Standards Index (PSI).

    With its inclusion, the PSI will reflect six pollutants: sulphur dioxide, PM10 (particulate matter), PM2.5 (fine particulate matter), nitrogen dioxide, carbon monoxide and ozone.

    The three-hour PSI will also be changed to be based on PM2.5 concentrations, instead of PM10 concentrations. Hourly PM2.5 concentrations will also be made available every hour.

    With the new system, more days will be classified as having moderate air quality, rather than good air quality.

    The National Environment Agency also cautioned that there will be more days with moderate PSI, even if the actual amount of pollutants in the air remains unchanged. This, it said, is "purely due to the integration of the PM2.5 concentrations into the PSI scale".

    There will be a small percentage of days with unhealthy, or worse, air quality due to transboundary haze.

    PM2.5 is a fine particulate matter less than 2.5 microns in size, and over-exposure to it can increase the risk of heart and lung illnesses and reduce an individual's lifespan.

    Assistant Professor Jason Cohen from the National University of Singapore (NUS), who specialises in climate change, said the revised readings will have more impact as Singapore lies in a region where PM2.5 tends to exceed the healthy threshold more often than other pollutants.

    "I don't think people should be any more concerned. In fact, this will give the Government and companies better targets to aim for," said Dr Cohen.

    He added that PM2.5 is a widely used air-quality measurement standard and its incorporation allows for easier comparison. "It lets you know where you stand objectively and where other countries stand in relation," he said.

    Environment minister Vivian Balakrishnan said the revised index will "simplify the reporting system" while providing more raw data for academics and scientists to use for research.

    Dr Balakrishnan also announced yesterday the appointment of an International Advisory Panel on Transboundary Pollution, to study and give recommendations pertaining to international laws and cross-border pollution, as well as steps which can be taken by Singapore.

    The panel will be chaired by Professor S. Jayakumar and Professor Tommy Koh, and is due to give its recommendations later this year.