Is it safe to exercise outdoors in haze?

It depends on the 1-hour PM2.5. Up to 55 µg/m³ normal activities are fine; at 56–150 reduce strenuous exercise; at 151–250 avoid it; above 250 minimise all outdoor activity (NEA). Vulnerable people should avoid strenuous activity from 56.

Who counts as vulnerable in haze?

NEA's guidance singles out the elderly, pregnant women, children, and people with chronic lung disease or heart disease. They should avoid strenuous activity from Band 2 (above 55 µg/m³).

Should I check the 1-hour PM2.5 or the 24-hour PSI?

Use the 1-hour PM2.5 to decide what to do in the next hour, and the 24-hour PSI to plan tomorrow. The PSI is a 24-hour rolling average, so it moves slowly.

Running and cycling in haze: what NEA's bands mean

At 56–150 µg/m³ reduce strenuous outdoor activity; at 151–250 avoid it; above 250 minimise all outdoor activity. Vulnerable people should avoid strenuous activity from 56 upward. These are NEA's activity guidelines for the next hour.

Singapore now · as at 10:00 SGT

100 µg/m³ · Elevated (1-hour PM2.5, NEA official, worst region)

NEA Band 2: reduce strenuous outdoor activity for the next hour — go easy and short, or move indoors. Stop if you cough or feel chest tightness.

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What to do at each level

By 1-hour PM2.5 (µg/m³) band
Band	Healthy adults	Vulnerable people
Normal 0–55	NEA Band 1: continue with normal activities.	NEA Band 1: continue with normal activities.
Elevated 56–150	NEA Band 2: reduce strenuous outdoor activity for the next hour — go easy and short, or move indoors. Stop if you cough or feel chest tightness.	NEA: vulnerable persons should avoid all strenuous activity for the next hour at Band 2 or above.
High 151–250	NEA Band 3: avoid strenuous outdoor activity for the next hour. Move indoors or rest.	NEA: vulnerable persons should avoid all strenuous activity for the next hour at Band 2 or above.
Very High ≥251	NEA Band 4: minimise all outdoor activity for the next hour. Use a treadmill or rest.	NEA Band 4: minimise all outdoor activity for the next hour. Use a treadmill or rest.

Basis: Follows NEA's activity guidance for the 1-hour PM2.5 bands.

Why hard exercise matters more

Hard exercise makes you breathe more air, more deeply and through the mouth, so you take in more smoke particles than at rest.

What to do instead

Use a treadmill, a gym or an indoor class, or do light walking and stretching at home. At Band 2 you can still do lighter exercise outdoors if you are healthy; shorten it and go easy.

Warning signs

Stop and move indoors if you cough, wheeze, feel chest tightness, dizziness or unusual breathlessness, and seek medical help if symptoms do not settle.

Steps

Check the 1-hour PM2.5 for your region.
Up to 55: normal activities. 56–150: go easy and short, or move indoors.
Above 150: avoid strenuous outdoor exercise for the next hour.
If you are vulnerable, avoid strenuous activity from 56 upward.
Stop if you cough or feel chest tightness.

Sources

NEA 1-hour PM2.5 readings (Singapore) — National Environment Agency (NEA), Singapore · official site · API / docs
haze.gov.sg regional haze situation and outlook — NEA, drawing on the ASEAN Specialised Meteorological Centre · official site

More guides

Sports training and matches in haze · Children, school PE and recess in haze · Commuting and masks in haze · Windows, purifiers and indoor air during haze · Drying laundry outdoors in haze · Outdoor dining and events during haze · Pets in haze

General information, not medical advice. Follow your doctor and your school, league or organiser's final call. Data come from official sources; see data sources.