The National Environment Agency has continued to refuse citizen calls for it to provide 1-hour Pollutant Standards Index (PSI) readings, citing lack of health studies which allow the conversion of raw data into meaningful 1-hourly PSI readings.
NEA pollution control project director and chief scientific officer Indrani Rajaram said yesterday: “If tomorrow, there is a very rigorous health study that tells us that (there is a) one-hour PM2.5 concentration that is harmful, we will use that to do a conversion. But at the moment, studies out there don’t give you a number supported by health studies.”
PSI is calculated by inputting raw pollutant concentration data into a formula that takes into account breakpoints – upper and lower concentration limits derived from health studies – with a machine used by NEA to help measure the concentration of PM2.5 in the air.
The NEA has asked Singaporeans to use the 3-hour PSI readings to formulate their plans for daily activities instead.