Most haze advice assumes it will be gone in a few days. This year it hasn't been. Since 6 October, Singapore's 24-hour PSI has sat mostly in the Unhealthy range, and on 10 October NEA said dry conditions were expected to continue over parts of Sumatra and Kalimantan, with smoke likely to keep drifting in on the prevailing winds.
So the question changes. It is no longer "should I run today?" — our PSI guide covers that. It is "how do I keep training well for several weeks without breathing bad air for every session?"
Here is how we would approach it.
1. Plan in weeks, not days
The worst haze-season habit is deciding every morning from scratch. You end up skipping sessions on bad days and cramming on good ones.
Instead, set a weekly shape that works whatever the air does, then slot outdoor runs in only when conditions allow. NEA's advice for healthy adults in the Unhealthy range is to reduce prolonged or strenuous outdoor physical exertion — so the plan keeps the hard and long work indoors by default.
2. A haze-week template
| Day | Default session | If PM2.5 is Normal |
|---|---|---|
| Mon | Strength, 40–45 min | — |
| Tue | Treadmill intervals, 30–40 min | — |
| Wed | Bike or rower, 40 min easy | Easy outdoor run, 30–40 min |
| Thu | Rest, mobility or pilates | — |
| Fri | Indoor quality: bike or row intervals | — |
| Sat | Long session indoors: 45–60 min treadmill easy + 20–30 min bike | Shorter easy outdoor run instead of the long run |
| Sun | Rest or easy indoor session | — |
The outdoor column is a bonus, not the plan. If the air never allows it, the week still works. Session ideas are in six indoor swaps for haze days.
3. Catch the windows
Haze is not constant through the day. Readings move with wind and rain, and a shower or a wind shift can bring the 1-hour PM2.5 down for a few hours.
- Check the 1-hour PM2.5 on myENV or haze.gov.sg right before you go — not the night before. NEA advises using it for immediate activities.
- Keep one or two days flexible so you can move an easy run into a clearer window.
- Easy only, even in a window. A clean hour is a chance for an easy run, not for the intervals you missed.
4. If you are racing the Standard Chartered Singapore Marathon
SCSM is on 5–6 December — about eight weeks away. A few weeks of haze changes how you train, not whether you can race.
- Keep one quality session a week, indoors. That is what holds fitness.
- Split the long run. A 60-minute treadmill run plus 30 minutes on the bike keeps the time on your legs without two hours on a belt.
- Don't try to make it all up when the air clears. Jumping straight back to full mileage is a bigger risk than the missed weeks.
- Be honest about the goal. If the haze takes three or four weeks out of your build, a time goal may need adjusting. Finishing well is still a good race.
More on race-day kit in our SCSM 2026 race-day guide.
5. Look after the rest of your day
Training is one hour. The other 23 matter too.
- Keep windows shut on bad days, especially in the room you sleep in.
- Commute smart. Long walks outdoors add up even if you never run.
- Sleep and eat well. A heavy indoor training week on poor sleep is harder on you than it looks.
6. Listen to your body
Stop and get medical advice if you notice a persistent cough, chest tightness, unusual breathlessness, dizziness or anything that doesn't feel right. If you have asthma, a heart or lung condition, or are pregnant, follow NEA's advice for vulnerable groups and your doctor's advice rather than any training plan — including this one.
7. When the haze clears
- Week one back: easy runs only. Let your legs and lungs re-adjust to outdoor running and heat.
- Rebuild over two weeks to your normal volume.
- Don't chase missed miles. Pick up your plan from where your fitness is now, not where it would have been.
A haze season is a few weeks out of a running year. Handled well, it barely shows.
Frequently Asked Questions
How long does the haze season usually last?
It depends on the fires and the winds, and it varies a lot by year. Follow NEA's daily haze updates for the current outlook rather than planning around a fixed end date.
Can I keep training for a marathon during the haze?
Yes, mostly indoors. Keep one quality session a week, split the long run between treadmill and bike, and run outdoors only in clean-air windows at an easy effort.
Is it worth running outside when the PSI is borderline?
Use the 1-hour PM2.5 for the decision, not the 24-hour PSI. If it is in the Normal band, a short easy run is reasonable for healthy adults. If it is Elevated or higher, take it indoors.
Should I take a full break instead?
You don't need to. Indoor sessions keep fitness ticking over. A full break is fine if you are unwell or simply need one.
What if I feel fine running in the haze?
Feeling fine is not the same as the air being fine. NEA's advice for the Unhealthy range is to reduce prolonged or strenuous outdoor exertion, whether or not you notice symptoms.
Haze information and health advisories in this article are taken from NEA. It is general information, not medical advice. If you have a medical condition or feel unwell, follow your doctor's advice.