Haze and outdoor activities in Singapore: a Plan B rule

For haze and outdoor activities in Singapore, check two numbers from the National Environment Agency (NEA): the 24-hour PSI forecast the day before, to decide whether an outdoor plan should stay, and the 1-hour PM2.5 reading just before you set off, to decide whether to go now. NEA’s advisories put it in one line: “Refer to the 1-hr PM2.5 for immediate activities, and the 24-hr PSI forecast to plan ahead.”

This matters now. At 5pm on Saturday 17 October 2026, the air-quality panel on NEA’s website showed a 24-hour PSI of 131 to 193 (Unhealthy) and a 1-hour PM2.5 of 95 to 200 µg/m³ (Band 2, Elevated, to Band 3, High). NEA’s latest advisory when we checked, of 16 October, forecast a 24-hour PSI of 150 to 230 (Unhealthy to Very Unhealthy) for 17 October. For 17 October that advisory told healthy people to avoid prolonged or strenuous outdoor exertion, the elderly, pregnant women and children to minimise outdoor activity, and people with chronic lung or heart disease to avoid it, so many outdoor plans this weekend are a Plan B decision already.

This is general information, not medical advice, and readings change by the hour, so treat ours as a dated snapshot.

Which reading should a group check: PM2.5 or PSI?

Both, for different questions. NEA’s FAQ says the PSI forecast, being less volatile, suits forward planning of outdoor activities that last many hours, while the 1-hour PM2.5 is for immediate decisions such as whether to go for a walk or run now. At the 16 October press conference the minister gave a group run as the example: check the next day’s 24-hour PSI forecast when planning, then check the 1-hour PM2.5 again before setting off, and “if it is elevated, you should cancel the run.” She added that readings differ by region, so check the one for where you will be.

Two cautions. NEA says the health impact “is dependent on one’s health status, the PSI level, and the length and intensity of outdoor activity”, so one reading can mean go for one person and stay in for another. And a forecast is a reason to prepare, not a promise: the minister said the PM2.5 reading spiked suddenly on Wednesday 14 October, particularly in the west.

What does NEA’s advice mean for each person in the group?

NEA words its advice for three groups: healthy people; the elderly, pregnant women and children; and people with chronic lung or heart disease. This card condenses the FAQ’s 24-hour PSI table and the October advisories’ 1-hour PM2.5 lines. Our suggestion, not NEA’s: set the rule by the most sensitive person in the group, not the average.

Clock 1, tomorrow (24-hour PSI forecast):

• Good or Moderate (0 to 100): normal activities for everyone.
• Unhealthy (101 to 200): healthy people reduce prolonged or strenuous outdoor physical exertion; the elderly, pregnant women and children minimise it; people with chronic lung or heart disease avoid it.
• Very Unhealthy (201 to 300): healthy people avoid prolonged or strenuous outdoor physical exertion; the elderly, pregnant women and children minimise outdoor activity; people with chronic lung or heart disease avoid outdoor activity.
• Hazardous (above 300): healthy people minimise outdoor activity; everyone else avoids it.

Clock 2, now (1-hour PM2.5 band):

• Band 1, Normal (55 µg/m³ and below, says the FAQ): normal activities.
• Band 2, Elevated (55 to 150 µg/m³): healthy people reduce strenuous outdoor activity; the other two groups avoid strenuous outdoor activity for the next hour.
• Band 3, High: healthy people avoid strenuous outdoor activity; the other two groups avoid all outdoor activity for the next hour and may wear a mask to reduce exposure.

The pages we could open give no separate line for Band 4, Very High; NEA points to the personal guide on haze.gov.sg, which we could not open. At the lower levels the wording covers exertion only, so whether a seated picnic, a show or a queue counts is the group’s call; at Very Unhealthy PSI or High PM2.5 it covers all outdoor activity for the more vulnerable groups. NEA’s 4 September release says People’s Association community activities are guided by the 24-hour PSI forecast. The Haze Task Force’s 9 October release adds that once the PSI crosses into Very Unhealthy, sport organisers and facility owners should consider modifying or suspending outdoor and non-air-conditioned activities, and that ActiveSG sport centres adjust their operations to the 24-hour PSI; check with your centre. Our guides to community exercise sessions and sports tournaments cover the organiser’s side.

What do venues say about haze, rain and cancellations?

Rain rules are written down; haze rules mostly are not, though two park operators acted on 17 October. This is what the pages said when we read them that day.

• Singapore Botanic Gardens: its notices page (last updated 16 October 2026) says all tours on the weekend of 17 October are cancelled “in light of the elevated PSI readings”, and that during inclement weather the Water Play, Rain Forest, Learning Forest and Rambler’s Ridge close.
• Jurong Lake Gardens: a notice on its website says guided tours on 17 October are cancelled due to haze conditions.
• Esplanade: its general advisory says it is watching air quality in line with NEA guidelines and that some outdoor performances may be cancelled if conditions reach unhealthy levels; no threshold is given, so follow its social channels. An event page FAQ says outdoor shows may be delayed, relocated or adjusted due to weather, ticket buyers of a cancelled show are told where to get a refund, and free programmes issue no tickets, so refunds do not apply. Kalaa Utsavam’s free outdoor sets from 20 November fall under this; see our Kalaa Utsavam guide.
• Borealis, Supertree Grove: the Gardens by the Bay page says “Borealis will be cancelled in the event of rain during show times”. Shows run every Saturday, Sunday and Monday, 8pm to 8.30pm, with free admission. It does not mention haze.
• NParks camping permit: the camping page says the permit “is non-cancellable” and “You cannot cancel if it rains or if you cannot make it on the day of your booking”, and the date and location cannot be changed. Each tent needs a permit for up to 6 people. It does not mention haze, and it says “Last updated on 28 November 2023”, so ask NParks before relying on anything else.

None of these pages sets a lightning rule. If thunder is forecast, ask the venue before the day.

Who decides, and by when? A Plan B message to copy

When a venue cancels, as the Botanic Gardens did with its tours, the decision is made for you. When it is silent, your group decides; for a ticketed event, ask the organiser about refunds before the day. Agree the rule early, and pair it with our group-chat plan for the meeting point and end time.

Template to adapt (our suggestion, not an NEA rule): “Plan: [day, time, place]. We go ahead outdoors only if the 24-hour PSI forecast for [day] is Good or Moderate and the 1-hour PM2.5 at the final call is Band 1. We swap if the forecast is Unhealthy or worse, PM2.5 is Band 2 or higher, or the venue cancels. Indoor swap: [named place], same time, food assigned. Decider: [one name]. Forecast call: [day, time]. Final call: [day, time], at least an hour before the start. Anyone can sit out without giving a reason. Nothing non-refundable is bought before the forecast call.”

Worked example (illustrative, not a real group). Twelve people plan a Saturday picnic at 11am, including two children and one grandparent, so the organiser applies NEA’s advice for the elderly, pregnant women and children to everyone.

1. Wednesday: the group agrees the template and names an indoor swap, a flat with the food already split.
2. Friday evening, forecast call: the organiser opens the newest advisory and checks its date. Suppose it reads like NEA’s of 16 October: 150 to 230, Unhealthy to Very Unhealthy. NEA’s advice for the elderly, pregnant women and children at that level is to minimise outdoor activity, so the template moves the picnic indoors that evening, with no need to wait.
3. If the forecast had been Moderate: both plans stay alive until the final call at 10am Saturday. Band 1 means “Going ahead”; Band 2 or 3 means “Swapping to [indoor place], same time”.

If the swap is a home, our small gathering checklist helps with the indoor version.

Do you need an N95 mask for an outdoor event?

Usually not for the event itself. NEA’s FAQ says N95 masks are not needed for short exposure, such as commuting or walking from a bus stop to a mall, or indoors. A healthy person who has to be outdoors for several hours when air quality is Hazardous (PSI above 300) may reduce exposure with one. People with chronic lung or heart disease, the elderly and pregnant women should avoid or minimise outdoor activity when it is Very Unhealthy (above 200), and may wear one if they have to be outdoors for several hours; those with severe lung or heart problems who have difficulty breathing should consult their doctor first. Since 14 October the Government has been distributing N95 masks to eligible vulnerable Singaporeans at Community Clubs and vending machines, says NEA’s 14 October update, which lists who qualifies.

What to check before you leave home

• The date and 24-hour PSI forecast on NEA’s newest advisory, then the 1-hour PM2.5 for your region just before you leave.
• Whether anyone has a chronic lung or heart condition, asked privately; NEA advises keeping medication on hand.
• The venue’s own notices for haze, rain, closures and refund terms.
• Water for everyone, an indoor swap, one decider and one final-call time, in writing.

Send the Plan B message before anyone buys anything non-refundable. More group guides are in the planning topic.

Common questions