Western Singapore's 24-hour PSI read 125 at 8am on 20 October 2026, in the unhealthy band that runs from 101 to 200, after a peak of 230 on 18 October (NEA, 2026). The 24-hour PM2.5 was 78 µg/m³, more than 5 times the WHO guideline of 15 (WHO, 2021). Shorten the ride.
The island is not one number today. Central reads 114, east 99, south 96 and north 89, so only the west and centre are unhealthy and the other three regions are back in the moderate band (NEA, 2026).
Key takeaways
- Western Singapore's 24-hour PSI was 125 at 8am on 20 October 2026, after a peak of 230 at 11am on 18 October (NEA, 2026).
- The PM2.5 sub-index in the west was also 125, the same as the headline PSI, so smoke particles are setting the number (NEA, 2026).
- In Singapore hospital records, each 30-unit PSI rise came with 4% more heart attacks and 2.3% more respiratory emergency visits (Ho et al., 2019; Chan et al., 2020).
- Motorcycle riders in Makassar breathed 4 times the PM2.5 of car riders on the same roads, so the station number understates a rider's dose (Patel et al., 2016).
What the monitors and studies actually measured
The PSI is a 24-hour index, so each reading still averages in yesterday's smoke. That is why it climbs and falls slowly. The west read 230 at 11am on 18 October, 161 at midnight on 19 October and 115 at midnight on 20 October (NEA, 2026).
Since midnight it has crept back up, from 115 to 125 by 8am. A falling trend over three days does not mean this morning is clearing (NEA, 2026).
Researchers have measured what such readings do to people. Chan and colleagues matched 5.79 million emergency visits to daily PSI from 2010 to 2015. Respiratory emergency visits rose 2.3% for each 30-unit PSI rise (Chan et al., 2020).
Ho and colleagues did the same with 53,948 heart attacks. Each 30-unit rise came with 4% more, and days in the unhealthy band had 9% more (Ho et al., 2019).
Why a rider breathes more than the station says
Average exposure on motorcycles against cars on the same Makassar trips. For PM10 the gap was 13 times.
Source: Patel et al., Science of the Total Environment, 2016That study was not a haze week, so the gap in haze is probably wider, but nobody has measured it here. A rider sits in open air, in the exhaust plume of the vehicle ahead, with no cabin filter (Patel et al., 2016).
Black carbon, a traffic soot that no public index reports, shows the same pattern. In Hanoi it averaged 29.4 µg/m³ on motorcycles against 10.1 in buses (Quang et al., 2021).
Commuting is also the day's biggest spike. In a 24-hour monitor study of 46 Singapore schoolchildren, exposure was higher in haze and higher again while commuting (George et al., 2020).
A 125 on the board is an average, not your ride. Check the hourly PM2.5 feed before you leave and again before the trip home.
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Filters haze PM2.5 on every ride
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What to do on your ride today
- Shorten or move the ride. Both regions are in the unhealthy band, and NEA advises reducing outdoor activity at these levels (NEA haze portal, 2026).
- Wear a fitted N95 or KN95 and seat it every time. In Makassar, only surgical masks lowered exposure consistently, and a loose edge wastes any filter (Patel et al., 2016).
- Pick the route with fewer traffic lights. Queued exhaust sits on top of the haze.
- Re-check before the ride home. The index lags, so the evening can be worse than the morning.
- For filtered air that does not depend on mask fit, look at an active HEPA helmet system.
For the bigger picture, see when the haze will be gone and the live haze map for riders.
Frequently asked questions
What is the PSI in Singapore today?
At 8am on 20 October 2026, the 24-hour PSI was 125 in the west, 114 in the central region, 99 in the east, 96 in the south and 89 in the north (NEA, 2026). Check the live feed for the current hour.
What does a PSI of 125 mean?
Readings of 101 to 200 are classed as unhealthy, and 51 to 100 as moderate (NEA haze portal, 2026). The advice for the public is to reduce outdoor activity.
Is the PSI the same as PM2.5?
No. The PSI blends several pollutants. In the west today the PM2.5 sub-index was 125, equal to the PSI, so smoke particles are the driver (NEA, 2026).
The research behind this: 5 studies
Peer reviewed work this post is built on. Each card says what was measured, what was found, and what it cannot tell you.
Haze exposure in Singapore schoolchildren
- What they measured
- A portable monitor on 46 Singapore schoolchildren for 24 hours, with hourly activity logs, in haze and non-haze periods. Haze particles were then tested on human bronchial cells.
- What they found
- Exposure was higher in haze and higher again while commuting, and haze particles drove more inflammatory signals in the cells.
- What it can't tell you
- Children, not riders. The cell test is a lab model, not a clinical outcome.
PSI and emergency care, nationwide
- What they measured
- 5,791,945 emergency visits and 1,552,187 admissions at Singapore public hospitals from 2010 to 2015, matched to daily PSI.
- What they found
- No link to total visits. But each 30-unit PSI rise came with 2.3% more respiratory emergency visits and 2.7% more respiratory admissions.
- What it can't tell you
- Daily PSI is an island average, not personal dose, and the effect per unit is modest.
PSI and heart attacks
- What they measured
- All 53,948 heart attacks in Singapore's national registry from 2010 to 2015, compared with PSI on the days around each event.
- What they found
- Each 30-unit PSI rise came with 4% more heart attacks. Days in the "unhealthy" band had 9% more.
- What it can't tell you
- An association from registry data. It does not prove haze caused any single event.
Motorcycle vs car exposure
- What they measured
- Handheld particle counters on motorcycle, minibus and car trips in Makassar, Indonesia, plus tests of surgical masks, bandanas and motorcycle masks.
- What they found
- Against cars, average motorcycle exposure was 4 times higher for PM2.5 and 13 times higher for PM10. Only surgical masks lowered it consistently.
- What it can't tell you
- A non-haze baseline, so the gap in a haze week is probably larger, but that was not measured.
Black carbon on a motorcycle
- What they measured
- Black carbon sensors running at the same time on motorcycles and in bus and car cabins in Hanoi.
- What they found
- Average black carbon was 29.4 µg/m³ on motorcycles against 10.1 in buses.
- What it can't tell you
- A pilot study in one city. Black carbon sits in no public index, so no station reports it.
Sources
- National Environment Agency, Singapore (2026). Real-time 24-hour PSI and PM2.5 feed, data.gov.sg. Pulled 20 October 2026, 8am SGT, with hourly history for 16 to 20 October.
- National Environment Agency, Singapore (2026). Haze portal: PSI bands and descriptors. Viewed 20 October 2026.
- World Health Organization (2021). WHO global air quality guidelines: particulate matter, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide.
- Chan, S. L. et al. (2020). Impact of air pollution and trans-boundary haze on nation-wide emergency department visits and hospital admissions in Singapore. Annals of the Academy of Medicine, Singapore.
- Ho, A. F. W. et al. (2019). Time-stratified case crossover study of the association of outdoor ambient air pollution with the risk of acute myocardial infarction in the context of seasonal exposure to the Southeast Asian haze problem. Journal of the American Heart Association.
- Patel, D., Shibata, T., Wilson, J., Maidin, A. (2016). Challenges in evaluating PM concentration levels, commuting exposure, and mask efficacy in reducing PM exposure in growing, urban communities in a developing country. Science of the Total Environment.
- Quang, T. N. et al. (2021). Motorcyclists have much higher exposure to black carbon compared to other commuters in traffic of Hanoi, Vietnam. Atmospheric Environment.
- George, S. et al. (2020). Personal level exposure and hazard potential of particulate matter during haze and non-haze periods in Singapore. Chemosphere.
Written by Ash, mechanical engineer and founder of Easi Breezi, building an active HEPA filtration system for motorcycle helmets (patent pending). Based between Hong Kong and Bali, riding daily in the traffic this blog writes about.