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    Jun 28, 2016

    NEA further clears air on hourly PM2.5 readings

    THE National Environment Agency (NEA) has introduced bands and descriptors for one-hour concentration readings of fine particles called PM2.5 to help the public make sense of the readings and plan their immediate activities.

    While the agency has been publishing such one-hour readings since 2014, it is now providing breakdowns of what constitutes normal to very high levels of 1-hour PM2.5 concentrations.

    For instance, the range of 0-55 micrograms per cubic metre is described as "normal" while anything above 250 micrograms per cubic metre will be described as "very high".

    Still, the concentration bands do not state what levels are healthy or not, unlike the 24-hour Pollutant Standards Index (PSI), which is used by authorities here as the reference for health advisories.

    Minister for the Environment and Water Resources Masagos Zulkifli, who made the announcement yesterday, said there is "no strong medical study" to show the impact of short-term exposure to PM2.5 particles on one's health.

    "In any case, if you are sensitive to such particles, or you have some form of ailment that makes you sensitive to such particles, consult your doctor," he added.

    PM2.5 pollutants are smaller than 2.5 microns in diameter, or a 30th the diameter of a human hair, and the body is not equipped to filter them out, unlike coarser particles.

    Long and regular exposure to PM2.5 is linked to higher risk of death from complications such as lung cancer or heart disease.

    The three-hour PSI reading will be phased out by year end.

    Weather scientist, Associate Professor Koh Tieh Yong of SIM University, said the one-hour PM2.5 readings are a more "direct and sensitive measure" of fine-particulate pollution than the three-hour PSI.

    However, Erik Velasco of the Singapore-MIT Alliance for Research and Technology said that having different air quality indicators can be confusing and the one-hour PM2.5 bandings do not provide any recommendations.