Singapore PSI & haze today
Air quality is unhealthy at its worst right now — Central is reading 105 on the 24-hour PSI as of 14 Sept, 1:00 pm.
Singapore measures air quality with the Pollutant Standards Index (PSI), published hourly by the National Environment Agency for five regions — north, south, east, west and central. The figure most people mean by "the PSI" is the 24-hour PSI, which averages the past day and is what NEA's health advisory is written against.
During a haze episode the 24-hour PSI lags what you can actually smell outside, because it is still carrying yesterday's cleaner air. The 1-hour PM2.5 reading is the one that moves first, and NEA publishes a separate personal guide against it for deciding whether to go out in the next hour. Both are shown below.
For travellers crossing to Johor, haze rarely closes a checkpoint, but it does change how long you want to be sitting in a queue with the windows down. The north reading covers Woodlands and the west covers Tuas.
PSI by region
24-hour PSI and 1-hour PM2.5 · reading of 14 Sept, 1:00 pm
| Region | 24-hr PSI | Band | PM2.5 (1-hr) |
|---|---|---|---|
| North· Woodlands | 81 | Moderate | 75 µg/m³ |
| West· Tuas | 93 | Moderate | 69 µg/m³ |
| Central | 105 | Unhealthy | 113 µg/m³ |
| East | 93 | Moderate | 71 µg/m³ |
| South | 84 | Moderate | 68 µg/m³ |
What NEA advises at unhealthy
For planning the day ahead, against the 24-hour PSI of 105 in Central.
- Healthy persons
- Reduce prolonged or strenuous outdoor physical exertion
- Elderly, pregnant women, children
- Minimise prolonged or strenuous outdoor physical exertion
- Persons with chronic lung disease or heart disease
- Avoid prolonged or strenuous outdoor physical exertion
Going out in the next hour
NEA's personal guide runs off the 1-hour PM2.5, currently 113 µg/m³ in Central (56–150 µg/m³ band). Use this rather than the PSI for anything immediate, such as a run.
- Everyone
- Reduce strenuous outdoor activity for the next hour
- Vulnerable persons
- Avoid strenuous outdoor activity for the next hour
The elderly, pregnant women, children, and persons with chronic lung disease or heart disease.
The full 24-hour PSI health advisory
| PSI | Healthy persons | Elderly, pregnant women, children | Chronic lung or heart disease |
|---|---|---|---|
| Good0–50 | Normal activities | Normal activities | Normal activities |
| Moderate51–100 | Normal activities | Normal activities | Normal activities |
| Unhealthy101–200Now | Reduce prolonged or strenuous outdoor physical exertion | Minimise prolonged or strenuous outdoor physical exertion | Avoid prolonged or strenuous outdoor physical exertion |
| Very Unhealthy201–300 | Avoid prolonged or strenuous outdoor physical exertion | Minimise outdoor activity | Avoid outdoor activity |
| HazardousAbove 300 | Minimise outdoor activity | Avoid outdoor activity | Avoid outdoor activity |
Advisory wording is NEA's, from its PSI and PM2.5 guide. NEA notes the guide is not intended to be prescriptive: for the general population, symptoms from short-term exposure such as throat or eye irritation are expected to resolve after leaving the exposure. Readings come from NEA via data.gov.sg.
Haze and PSI — common questions
What PSI level is considered unhealthy in Singapore?+
A 24-hour PSI above 100 is Unhealthy. NEA bands the index as 0–50 Good, 51–100 Moderate, 101–200 Unhealthy, 201–300 Very Unhealthy and above 300 Hazardous. The health advice changes at each band, and changes differently depending on whether you are a healthy adult or in a vulnerable group.
Is it safe to exercise outdoors when there is haze?+
NEA advises using the 1-hour PM2.5 reading, not the 24-hour PSI, for anything you are about to do in the next hour. Up to 55 µg/m³ you can continue normal activities. From 56 to 150 µg/m³ healthy people should reduce strenuous outdoor activity, and vulnerable persons should avoid it. Above 250 µg/m³ everyone should minimise or avoid outdoor activity entirely.
Who counts as a vulnerable person?+
NEA defines vulnerable persons as the elderly, pregnant women, children, and persons with chronic lung disease or heart disease. They get the stricter instruction at every level above the normal band.
Why is the PSI different in different parts of Singapore?+
Haze arrives on the wind, so the regions nearest the source read higher first. It is common for the west to be well above the east, or the reverse, depending on wind direction. This is why NEA publishes five regional readings rather than one national figure.
Does haze affect Woodlands and Tuas checkpoint crossings?+
Haze does not normally close a checkpoint or change immigration processing. What it changes is the experience of queuing: on a bad day a long wait is spent in the open air near the Causeway. Check the north reading for Woodlands and the west reading for Tuas, and the live camera feeds for how long the queue actually is.
How often are these readings updated?+
NEA publishes new readings hourly. This page reads them from data.gov.sg with a cache of at most ten minutes, so the figure shown is the most recent hourly reading NEA has released.