What Bangkok drivers and families must do this dust season

On the morning of Saturday, 24 October, people who opened the AirBKK app in Bang Khun Thian saw a dust reading of 43.4. Phasi Charoen and Bueng Kum read 38.6 and 37.6. All three districts had passed the 37.5 line, even with rain still falling over parts of the city. For parents taking children to weekend classes, or anyone out for a morning run, it was a clear sign that dust season was back.

Three days later, Bangkok Governor Chadchart Sittipunt chaired a meeting of the city's PM2.5 committee and set November 2026 to March 2027 as a period of strict monitoring, Daily News reported. The goal is to cut the number of days when dust exceeds the standard from 28 to no more than 20. One of the main measures that affects drivers directly is the Green List, which opened for registration on 22 October and stays open until 31 March 2027.

37.5 is the line where dust starts to affect health

PM2.5 is dust smaller than 2.5 microns, small enough to slip past the hairs in your nose and reach your lungs. The number in the app is the weight of dust in one cubic metre of air, in micrograms. Thailand's standard is 37.5. Anyone who sees a reading above that should treat the air that day as orange level, which starts to affect health, and above 75 is red, the most severe. The BMA's plan is tied to these two lines: 66 basic measures all year, 18 more when dust reaches orange and 6 more at red.

Bangkok's dust is usually worst from the end of one year to the start of the next, because the air is cool and still and the wind does not carry the dust away, so it hangs close to the ground. The main sources the BMA inspects are black smoke from diesel vehicles, construction sites, concrete plants, factories and boilers, and open burning. The BMA is also working with Nakhon Nayok province on rice stubble burning and factories outside the city, because dust does not stop at provincial borders.

The Green List is a pass for transport vehicles on bad dust days

The name sounds official, but the meaning is simple. It is a list of vehicles whose owners have serviced the engine, so they can drive into the low emission zone as normal on days when the BMA bans some vehicle types from the area because of heavy dust. A low emission zone is an area that high-polluting vehicles cannot enter during a crisis. According to the registration page on the BMA's website, the vehicles that can register are those registered under the Land Transport Act: passenger vehicles, vehicles carrying animals or goods, and small vehicles, which include four-wheel and six-plus-wheel transport vehicles.

The process starts at the garage, not on the website. The owner must change the engine oil and have the air filter blown out or replaced, and that work must be done on or after 1 October 2026. Then they sign up and fill in the form at greenlist.bangkok.go.th. Vehicles that pass get an electronic certificate showing they are on the list for the 2027 fiscal year. Last season, 80,254 vehicles registered, but by 2 November this year only 8,043 had, Thai Tabloid reported. Anyone who has not done it yet has until 31 March 2027, but the earlier it is done before the first bad dust day, the less there is to worry about when a job comes in.

The draft rule barring unlisted six-wheel trucks is not final

The rules for bad dust days this year are still a draft announcement the BMA is preparing. The draft covers combustion-engine vehicles with six or more wheels, which cannot enter Bangkok on days the announcement is in force unless they are on the Green List. Offenders may be fined up to 4,000 baht under the Land Traffic Act. Ordinary private cars are therefore not among the vehicles the draft bans, but a car that gives off black smoke can still be stopped at a black smoke checkpoint as before.

The BMA will decide whether to make an announcement from dust readings and a two-day forecast, looking at how many districts reach red, how many exceed the standard and how poorly the air is moving. Once it does, people in the area will get a warning on their phones through Cell Broadcast and see roadside LED signs, so transport drivers should keep emergency alerts switched on.

Families with children and older people should check the dust every morning

For most people, who do not drive a truck, the daily step is to check the dust before leaving home, on the BMA's AirBKK app or airbkk.com, which show readings by district. If the district where you live or where your child goes to school reaches orange, wear a mask that filters PM2.5 when outdoors and cut down on outdoor exercise, according to advice The Nation reported. Children, older people and anyone with a breathing condition should avoid outdoor activity, and anyone with a cough, difficulty breathing or stinging eyes should see a doctor.

The mask that filters dust this fine well is an N95, but it must be the right size, fitting snugly over the nose and under the chin, because a loose mask lets air in around the edges, according to Department of Health advice published by PPTV. Replace a mask when it gets loose, makes breathing hard, or is torn, dirty or wet. Anyone who sees black smoke from a vehicle, a construction site or burning can report it to the BMA through Traffy Fondue.

There are three things you can start today. Download AirBKK and set your home and work districts. Buy N95 masks in a size that fits each person at home. And if your household runs a transport vehicle, book the garage for an oil change and air filter service, then finish the Green List registration before 31 March 2027.

Sources

• Bangkok Metropolitan Administration: Green List registration form
• Daily News: 'ชัชชาติ' ถกรับมือ PM2.5 ตั้งเป้าลดวันค่าฝุ่นเกินมาตรฐานเหลือไม่เกิน 20 วัน
• Thai Tabloid: กทม. ถกคณะกรรมการ LEZ ลุยมาตรการเขตมลพิษต่ำปี 2570
• The Nation: Bangkok Issues Orange PM2.5 Smog Alert as Air Quality Slips in Three Districts
• PPTV: กรมอนามัยคาดแนวโน้ม PM 2.5 สูงขึ้น แนะเช็กค่าฝุ่น เปิดวิธีดูแลตัวเอง