Pasir Gudang, Johor, read an API of 174 at 5.50pm on Monday 12 October 2026, the highest of 23 areas in the unhealthy band of 101 to 200 (Bernama, 2026). It peaked at 190 on 9 October (Malay Mail, 2026). Treat it as a floor. In Taipei, motorcyclists' exposure climbed faster than the station reading did (Tsai et al., 2008).
By Monday evening, Pasir Gudang's API stood at 174, and schools in all of Johor were already ordered shut for Tuesday (Bernama, 2026).
Riders do not get a school closure. They get the same road, and a fixed station somewhere across town telling them how the air is.
Key takeaways
- Pasir Gudang's API was 169 at 11am and 174 at 5.50pm on 12 October 2026, so the afternoon was no cleaner than the morning (The Star, 2026; Bernama, 2026).
- Johor held the top two readings and seven of the 23 unhealthy areas on 12 October (Bernama, 2026).
- Taipei motorcycle commuters breathed 67.5 µg/m³ of PM2.5 on 28-minute trips, the highest of four commuting modes (Tsai et al., 2008).
- Thai motorcycle taxi drivers' personal PM readings did not track the monitoring stations at all (Samana et al., 2025).
What the monitors and studies actually measured
The API is a station number. Malaysia's Department of Environment publishes it hourly from 68 stations (The Star, 2026). It describes the air at one fixed point, not the air at your visor.
Researchers have measured that gap directly. In Taipei, Tsai and colleagues followed commuters on the same routes by motorcycle, car, bus and metro. Motorcyclists had the shortest trips, 28.4 minutes, and the highest PM2.5, 67.5 µg/m³.
For motorcyclists, the line linking exposure to the fixed station was steeper than 1, so exposure rose faster than the station did (Tsai et al., 2008).
In Thailand, Samana and colleagues wore air samplers on motorcycle taxi drivers across six provinces. The personal readings were independent of what the stations reported. In Pathum Thani, drivers averaged 410.9 µg/m³ of PM2.5 (Samana et al., 2025).
The studies disagree on exact numbers, because the cities and years differ. They agree that a rider's dose is not the station's number.
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Pasir Gudang breathes industry and smoke together
Pasir Gudang is an industrial zone. A 2025 model of its 10 industry groups, run on 2019 to 2021 data, put the area's API at 146.97 even without a smoke event, driven by nitrogen dioxide. That is unhealthy for sensitive groups (Tan et al., 2025).
Regional smoke arrives on top of that. A study of past haze years at Pasir Gudang and three other Malaysian stations traced the air to Sumatra and found weak links between PM10 and local traffic gases, pointing away from home-grown sources (Addiena A Rahim et al., 2023).
Singapore, across the strait, tells the same story. Its west region read PSI 173 at 8am on 13 October (NEA, 2026). PSI and API are different indices, so compare the trend, not the digits.
Your ride reads higher than the station
PM2.5 breathed by motorcycle commuters in Taipei, the highest of four commuting modes on the same routes.
Source: Tsai et al., Science of the Total Environment, 2008Malaysian outdoor workers show the cost. In a three-month cohort of 440 people, a peak PM2.5 of 122.9 µg/m³ came with significant changes in eye, nose and respiratory symptom scores, and outdoor workers were affected more than indoor ones (Sundram et al., 2022).
Riders are outdoor workers by another name. Idling at a red light with the smoke already thick is the part no station captures. Tsai's team found that motorcycles idling at traffic lights pushed commuter exposure up (Tsai et al., 2008).
Leave a gap at lights and drift to the lane edge, away from queued exhaust. Idling traffic adds its own plume on top of the haze.
What to do on your ride this week
- Check the live API before you leave. The Department of Environment portal updates hourly, and Pasir Gudang's reading shifted between morning and evening on Monday.
- Assume your reading is higher than the station. Use the API as a floor, not your dose.
- Cut your time in queued traffic. Pick the route with fewer lights, even if it is a few minutes longer.
- If you wear a mask, re-seat it every ride. A loose seal wastes the filter.
- For filtered air that does not depend on seal 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
Is the air unhealthy in Pasir Gudang today?
On Monday 12 October 2026 it was, with an API of 174 at 5.50pm, inside the 101 to 200 unhealthy band (Bernama, 2026). Check the live portal for the current hour.
Are Johor schools closed because of the haze?
Schools in Johor, Melaka, Negeri Sembilan and Putrajaya were ordered closed for Tuesday 13 October, along with some districts in Selangor and Pahang (Bernama, 2026).
Is the haze in Johor from Indonesia?
In past haze years, air at Pasir Gudang and other Malaysian stations traced back to Sumatra (Addiena A Rahim et al., 2023). Pasir Gudang's local industry adds its own load on top (Tan et al., 2025).
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.
Commuter PM exposure by transport mode
- What they measured
- Commuters' PM exposure on the same routes in Taipei by motorcycle, car, bus and metro, compared with fixed-site monitors.
- What they found
- Motorcyclists had the shortest trips (28.4 minutes) and the highest PM2.5, 67.5 µg/m³.
- What it can't tell you
- Measured in Taipei on set routes, so Johor roads and smoke events will differ.
Motorcycle taxi drivers' personal PM and PAH exposure
- What they measured
- Personal air sampling on motorcycle taxi drivers in six Thai provinces, January to March 2023, against station data.
- What they found
- Personal PM readings were independent of the stations. Pathum Thani drivers averaged 410.9 µg/m³ of PM2.5.
- What it can't tell you
- No individual lung function measure was significantly linked to PM, so it shows exposure, not harm.
Industrial air pollution in Pasir Gudang
- What they measured
- AERMOD dispersion modelling of 10 industry groups for SO2, NO2 and PM10 over 2019 to 2021.
- What they found
- The modelled API was 146.97, driven by NO2 and unhealthy for sensitive groups.
- What it can't tell you
- It is a model of industry only, with no smoke and no PM2.5, so it is a baseline, not a measurement.
PM10 in Malaysian haze episodes
- What they measured
- Hourly PM10, gases and weather from the Department of Environment at Kelang, Melaka, Pasir Gudang and Petaling Jaya in historic haze years.
- What they found
- Air masses came from Sumatra during haze episodes, and PM10 had only a weak link to local NOx.
- What it can't tell you
- It covers past haze years, not 2026, so it cannot split today's smoke by source.
PM2.5 and outdoor workers' health in Malaysia
- What they measured
- A two-cycle, three-month cohort of 440 participants, scoring eye, nose and respiratory symptoms against PM2.5.
- What they found
- PM2.5 peaked at 122.9 µg/m³, symptom scores changed significantly with it, and outdoor workers were affected more.
- What it can't tell you
- Observational, and asthma control showed no significant link, so it is not proof of cause.
Sources
- Bernama / The Malaysian Reserve (2026). 23 areas record unhealthy air quality, Pasir Gudang worst hit. Data from the Department of Environment APIMS portal.
- The Star (2026). Haze: 23 areas record unhealthy API as at 11am.
- Malay Mail / Bernama (2026). Haze: 36 areas record unhealthy API readings, Pasir Gudang highest at 190.
- Tsai, D.H., Wu, Y.H., Chan, C.C. (2008). Comparisons of commuter's exposure to particulate matters while using different transportation modes. Science of the Total Environment.
- Samana, K., Ito, K., Suthienkul, O., Ketsakorn, A. (2025). Analysis of PM-bound polycyclic aromatic hydrocarbons exposure among motorcycle taxi drivers in six central provinces in Thailand in winter. PLOS ONE.
- Tan, A.Z.L., Ho, W.S., Hassim, M.H., Abdullah, F., Lim, L.Y. (2025). Evaluation of industrial air pollution contribution by type of industry in Pasir Gudang using AERMOD. Environmental Monitoring and Assessment.
- Addiena A Rahim, N.A., Noor, N.M., Mohd Jafri, I.A. et al. (2023). Variability of PM10 level with gaseous pollutants and meteorological parameters during episodic haze event in Malaysia: domestic or solely transboundary factor? Heliyon.
- Sundram, T.K.M., Tan, E.S.S., Cheah, S.C. et al. (2022). Impacts of particulate matter (PM2.5) on the health status of outdoor workers: observational evidence from Malaysia. Environmental Science and Pollution Research.
- National Environment Agency, Singapore (2026). Real-time PSI readings, 13 October 2026, 8am. data.gov.sg.
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.