2023-10-09 00:00:00 Got haze in Singapore? Want to check PSI, pollution and PM2.5 readings around Singapore? Use SG Real PSI app! NEA's PSI reading is based on a 24-hour average. While it is a good measure of exposure, it tends to dampen the impact of sharp drops or increase in PSI readings in an hour. We have created what we think is a right implementation of NEA's official PSI formula on haze.gov.sg to deduce the actual, hourly PSI measurements from hourly PM2.5 readings.