Thailand Life Tools

Bangkok air quality (PM2.5)

AIR

Which months are smoggy, counted from official station data, and what to do on a bad day. For the reading right now, use the official apps.

WORST MONTH
Jan
ORANGE+ DAYS 2026
13/31
CHECKED

Days above Thailand’s 24-hour standard (37.5 µg/m³), Pollution Control Department station reports.

Short answer

DAYS AT ORANGE OR WORSE · AVERAGE PER MONTH

  1. 17Jan
  2. 9Feb
  3. 5Mar
  4. 1Apr
  5. 2May
  6. 0Jun
  7. 0Jul
  8. 0Aug
  9. 0Sep
  10. 1Oct
  11. 3Nov
  12. 10Dec
Bad season
November to March
Worst month
January: 15 of 31 days in 2024, 23 of 31 days in 2025, 13 of 31 days in 2026
No orange day
June to September

Average of the official reports 2024–2026, Chulalongkorn Hospital, Rama IV Road (Pathum Wan). Bar height: share of the month’s days above 37.5 µg/m³.

Bad days come and go within the season: check the official app before outdoor plans. The reading right now: AirBKK · Air4Thai

Bad-air days by month

Days at orange or worse (above 37.5 µg/m³ as a 24-hour average) out of days with data, and the worst day of the month, at Chulalongkorn Hospital, Rama IV Road (Pathum Wan). January 2024 to November 2026.

Month202620252024
January13/31worst 56.923/31worst 80.615/31worst 67.4
February5/28worst 50.916/28worst 68.67/29worst 74.1
March2/31worst 4211/31worst 72.63/31worst 52.4
April1/30worst 38.70/30worst 373/30worst 57.8
May0/31worst 30.90/31worst 295/31worst 42.9
June0/30worst 18.30/30worst 24.50/30worst 20.5
July0/31worst 24.50/31worst 23.30/31worst 23.2
August0/31worst 19.60/31worst 19.90/31worst 20.9
September0/30worst 21.9our average0/30worst 20.80/29worst 33.7
October0/31worst 35.6our average0/31worst 24.31/31worst 41.2
November0/4worst 28.8our averageso far2/30worst 47.23/30worst 43.8
December—7/30worst 51.613/31worst 50.2
  • Numbers from the Pollution Control Department’s station reports, which it marks as preliminarily checked data (published a month or two late).
  • “our average”: newer months worked out by this site from Air4Thai’s hourly values (average of each day’s hours, a day needs 18 of 24 hours); replaced by the official report when it is published.
  • “part data”: under 75 % of the month’s data (the report’s * is 50–75 %, ** under 50 %; on our averages, days are missing). “so far”: the month is not over.
The other two stations

Same counts for two general-area stations. A roadside station usually reads higher than one away from traffic.

Why these 3 stations: they are the Pollution Control Department stations nearest the areas most visitors stay in, and the only ones with official monthly reports (Bangkok’s district sensors have none). There is no such station at Chatuchak.

  • Chulalongkorn Hospital, Rama IV Road (Pathum Wan) · roadside · near: Siam, Silom, Lumphini Park
  • Government Public Relations Department (Phaya Thai) · general area · near: Victory Monument, Ari
  • Nonsi Witthaya School (Yan Nawa (Chong Nonsi)) · general area · near: Sathon, Chong Nonsi

Government Public Relations Department (Phaya Thai) · general area

Month202620252024
January7/31worst 42.911/31worst 57.45/31worst 49.3
February1/28worst 40.45/28worst 45.94/29worst 53.3
March0/31worst 33.47/31worst 58.31/31worst 39.2
April0/30worst 33.10/30worst 27.92/30worst 47.2
May0/31worst 23.20/31worst 23.11/31worst 38.9
June0/30worst 13.60/30worst 20.70/30worst 12.4
July0/31worst 19.30/31worst 19.10/31worst 11.1
August0/31worst 14.80/31worst 140/31worst 13.3
September0/30worst 15.9our average0/30worst 13.60/30worst 18.9
October0/31worst 26our average0/31worst 15.40/31worst 25.1
November0/4worst 19.4our averageso far1/30worst 37.80/30worst 27.1
December—0/29worst 36.40/31worst 26.8

Nonsi Witthaya School (Yan Nawa (Chong Nonsi)) · general area

Month202620252024
January7/25worst 47.817/31worst 69.213/31worst 60
February3/28worst 43.310/28worst 60.54/28worst 73.4
March0/31worst 34.76/31worst 65.62/31worst 43.3
April0/30worst 35.10/30worst 31.22/30worst 46.3
May0/31worst 25.80/31worst 23.90/31worst 35.6
June0/30worst 15.20/30worst 21.50/30worst 15
July0/31worst 21.40/31worst 20.40/31worst 18.1
August0/31worst 160/31worst 17.20/30worst 17.1
September0/24worst 18.6our averagepart data0/30worst 16.60/13worst 18.5part data
October0/31worst 28.1our average0/31worst 21.30/31worst 30.1
November0/4worst 21.8our averageso far1/30worst 40.80/30worst 36.5
December—4/31worst 45.84/29worst 40.5

Bad day today? What to change

Change the place first: move outdoor plans indoors or to a better day. Go by the number in the official app.

Colour (24-hour PM2.5)What to do
Blue · Green0–25.0Anything outdoors: rooftop bars, parks, the night bike ride.
Yellow25.1–37.5Outdoor plans are fine; if you are sensitive, keep long or hard exercise short.
Orange37.6–75.0Move outdoor plans indoors: a mall or a massage instead of a long walk. Keep rooftops and the bike ride for a better day.

Official advice (Pollution Control Department): Use protective equipment such as a PM2.5 mask every time you go out; limit strenuous outdoor activity.

Red75.1+Stay indoors where you can: malls, museums, a massage. Put rooftops, parks and the bike ride on another day.

Official advice (Pollution Control Department): Avoid outdoor activities; use protective equipment such as a PM2.5 mask every time you go out.

Shopping mallsRooftop barsNight bike rideBangkok tonight

Where to see the number now

Why the number differs from app to app

Thai apps show PM2.5 in µg/m³ with Thai colours. IQAir and other international apps usually show the US AQI, an index, so the same air looks like a bigger number.

ScaleWhere “bad” starts (24-hour)
Thailand (Air4Thai, AirBKK)µg/m³Above 37.5 µg/m³ is orange (standard since 1 June 2023); 75.1 and above is red
WHO guideline (2021)µg/m³15 µg/m³ (annual 5): a guideline level, not a law. Thailand’s 37.5 is WHO’s interim target 3
US AQI (IQAir and others)Index 0–500101 (35.5 µg/m³) is “unhealthy for sensitive groups”; 151 (55.5 µg/m³) “unhealthy” (2024 scale)
Thai PM2.5 colour bands (24-hour average)
Colourµg/m³Meaning
Blue0–15.0Very good
Green15.1–25.0Good
Yellow25.1–37.5Moderate
Orange37.6–75.0Starting to affect health
Red75.1+Affects health

Convert a number

Thai colour
—
Times the WHO guideline
—
US AQI
—

Uses only the published band tables; runs on your device and sends nothing. An app’s hourly number is not a 24-hour average, so the colours can differ.

Other reasons the numbers differ

  • Hourly or 24-hour: apps lead with the latest hour; the Thai colours and the standard are for a 24-hour average.
  • Where: a roadside station reads higher than a park. AirBKK shows districts; Air4Thai shows single stations.
  • Which sensors: IQAir mixes official stations with low-cost sensors, which read differently.

Government measures that affected visitors

Work-from-home requests, school closures, free transport and traffic rules, newest first. A line is added when a new one is announced.

  1. Work-from-home request

    Bangkok asked for work from home on 29–30 January 2026, with orange expected in 35 districts.

    The Nation

  2. Work-from-home request

    Bangkok asked for work from home on 12–13 January 2026.

    Pattaya Mail

  3. Work from home, voluntary

    The city said work from home on the bad days of early December was voluntary, not mandatory.

    The Nation

  4. 2026 plan

    Ten measures for 2026, among them a low-emission zone in all 50 districts, 500,000 vehicles on the “Green List Plus” and a target of 300,000 people working from home.

    The Nation

  5. Stricter vehicle smoke rule

    The black-smoke limit for vehicles was cut from 30 % to 20 % opacity.

    The Nation

  6. New work-from-home trigger

    Orange in at least 35 districts, with poor ventilation and many fire hotspots, now triggers a voluntary work-from-home request; one work-from-home day a week was planned for January–March 2026.

    The Nation

  7. Pollution control zone

    Bangkok was declared a pollution control zone in the Royal Gazette.

    The Nation

  8. Free trains and buses

    BTS, MRT and other electric trains and BMTA buses were free for seven days, 25–31 January 2025. It was not extended.

    Government Public Relations Department · The Nation

  9. Schools closed

    352 of 437 city schools in 31 districts closed, the most in five years (AFP, citing the city).

    AFP via Tuoi Tre News

  10. Work-from-home request

    Bangkok asked offices to let staff work from home on 20–21 January 2025, possibly to 24 January. Schools could close: up to 3 days by the principal and 7 by the district at orange, up to 15 days after 3 red days.

    BMA public relations (pr-bangkok.com)

Clean Air Bill: the Senate passed it with amendments on 9 July 2026; the House did not accept the amendments and a joint committee was set up (reported 3 September 2026). It is not law yet.

Questions

When is the air worst in Bangkok?
November to March. January had the most days at orange or worse in the official station data (15 of 31 days in 2024, 23 of 31 days in 2025, 13 of 31 days in 2026).
Is Bangkok’s air bad all year?
No. June to September had no day at orange or worse in any year of the reports at Chulalongkorn Hospital, Rama IV Road (Pathum Wan).
Why does IQAir show a higher number than AirBKK?
IQAir shows the US AQI, an index, while AirBKK and Air4Thai show µg/m³. 50 µg/m³ is orange in Thailand and an AQI of about 137 in the US scale. They also use different stations and time spans.
Should I cancel my trip in the smoggy season?
Most days, no: plan outdoor time for the better days and keep indoor options for the bad ones. People with asthma, heart or lung conditions should follow their doctor’s advice.
Where can I see the air quality right now?
AirBKK (Bangkok city) and Air4Thai (Pollution Control Department). This page shows no live reading.

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