Singapore 1-Hour Pollutant Standards Index (PSI)

1h-PSI based on PM2.5 readings map

1h-PSI readings over the last 24h

0 - 50 : Good - 51 - 100 : Moderate - 101 - 200 : Unhealthy - 201 - 300 : Unhealthy - Above 300 : Hazardous
Why do we provide 1h-PSI based on PM2.5 concentrations?
  • To provide near real time information for planning immediate activities, such as jogging.
  • To focus on the main air pollutant PM2.5.
  • To assist making better sense of PM2.5 readings by converting them to PSI scale.
How do we compute 1h-PSI based on PM2.5 concentrations?

The 1h-PSI based on PM2.5 concentrations is the PM2.5 PSI sub-index, calculated according to NEA methodology, but with the current PM2.5 reading instead of a 24h average.

Example: If PM2.5=100µg/m3, PSI=147

PSI stands for “Pollutant Standards Index”. It is a Singaporean index to evaluate the ambient air quality.

The 24h-PSI is calculated as follows:

  • The concentrations of six pollutants are measured every hour by Singapore air monitoring stations: particulate matter (PM10), fine particulate matter (PM2.5), sulphur dioxide (SO2), carbon monoxide (CO), ozone (O3) and nitrogen dioxide (NO2).
  • For each pollutant, the average concentration is calculated for five zones: West, East, North, South and Central.
  • For each pollutant/zone, the concentrations are averaged over the last 24 hours.
  • For each pollutant/zone, the 24h average concentration is converted in a PSI “sub-index” (i.e. a PSI value specific for this pollutant)
  • Finally, for each zone, the overall PSI value is calculated as the maximum of those sub-indices

Current and historical readings for PSI and individual pollutant are publicly available on NEA website.
For more information about PSI computation, refer to the NEA methodology.

The PSI map uses the latest PM2.5 readings from PM2.5 API

The PSI 24h trend chart uses the PM2.5 readings for the past 24 hours from PM2.5 API

Want to know where the Haze comes from?

Global Forest Watch is the most advanced hotspots monitoring platform. They provide hotspot information using NASA satellites, together with wind direction, fire risk map and plantation information.

The NEA regional Haze map provides hotspot information using NOAA satellites with daily analysis and visualisation of Haze plume.

The HazeTracker map provides hotspot information from NASA’s MODIS satellite, wind direction, and the boundaries of oil palm and pulpwood concessions in Indonesia. The map also features a map layer from NUS’s CRISP imaging centre that displays the latest (2015) land use data for Indonesia’s peatland areas, as analysed from satellite images.

Hotspot: satellite detection of an area with high temperature. Hotspots come with a confidence level and “high-confidence” hotspots represent fires.

In collaboration with DataKind SG. All source codes can be find here.

Special thanks to HackerspaceSG for providing space for project discussions!