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Subject: 20130627 NEA – why PSI headline but PM2.5 in fine print or absent?
Dear Minister Balakrishnan
I refer to online and published information on air quality which is inadequate for members of the public to make informed health-related decisions.
The government has continued to emphasize on the PSI figure despite PM2.5 having a greater impact on our health.
Eg table showing only PSI figures
This defies logic and common sense.
The 24 hourly PSI measures long term exposure for evaluation purposes. What the public, schools, construction companies etc need to know is the hourly or real-time data for planning activities.
NEA’s 24 hourly/3 hourly PSI does not correspond with the current clear/hazy view and is ill-suited for planning purposes.
When I am planning for outdoor activities, the view I see outside my window has to correspond with NEA’s PSI/PM2.5 figures. Currently, the emphasis on the 24 hourly PSI figure is akin to offering the public yesterday’s window view.
This followed by an advisory when the PSI reading is good leads to even more confusion.
The 3 hr PSI may be of slightly more help but there is still a time lag. There is a need for hourly/real time data which is what the public has been highlighting but the NEA has yet to understand this.
The US progressed to using the AQI 14 years ago. MOH’s FAQs continue to defend our use of the PSI despite evidence of a necessary ‘upgrade’.
There has been much research into air quality and even China and Mexico use AQI. AQI is also color coded and with only 1 unit of measurement, it is easily understood. PSI on the other hand requires 2 separate figures and confusion has arisen to the extent that most Singaporeans have mistaken a low PSI to mean good air quality despite an unhealthy PM2.5 reading.
The NEA should discard the dinosaur-age PSI and make real-time/hourly reading of PM2.5 available. Better still, convert to the AQI.
Clearly presented and easily understood colour coded information shown below. The NEA should have a similar page.
NEA’s forecast for 27 June till 6 p.m. – 24 hr PSI between 51 to 100 which is in the moderate range. At the same time, healthy persons have been adviced to “minimise prolonged or strenuous outdoor physical exertion”.
NEA’s website – normal activity when PSI is below 100 Health advisory for forecast PSI from 51 to 100? No, it’s due to PM2.5 forecast.
This contradiction resulted from the more influential PM2.5 figure. If it was insignificant, a health advisory would not have been issued.
For the NEA to continue emphasising on the PSI is, in this case, akin to putting the ‘Slow’ sign after the zebra crossing.
NEA is responsible for the resulting confusion and this will continue to increase over time.
Perhaps the best course of action would be a total conversion to AQI. Not now but when the haze crisis blows over.
The US EPA did not discard the PSI 14 years ago for cosmetic reasons.