What is Smoky Season aka Burning Season?

Smoky season is more of a nickname that refers to “burning” season. There’s plenty of haze, smog, and pollution trapped in the atmosphere for long periods of time. Officially of course it’s not a season at all and the rest of the year Chiang Mai has excellent weather.

What Causes the Smoky Season in Thailand?

The haze isn’t from a singular source, rather air pollution in Thailand results from various causes, human factors, seasonal factors, atmospheric conditions, and traditional agricultural methods such as:

• Crop burning, particularly slash-and-burn farming
• Vehicle emissions
• Factory emissions 
• Burning of garbage
• Forest fires
• Air pressure

Is Smoky Season Only in Chiang Mai?

No, the smoke encompasses much of the land areas of Laos, Myanmar, Cambodia, Thailand, and parts of Vietnam. Neighboring countries like Myanmar and Laos heavily contribute to the air pollution which blows over and covers much of Thailand.

As you can see here on this map, each red dot indicates fire and the issue of burning is widespread across the region. This is typical of every burning season which is not just in Chiang Mai.

Is The Smoky Season Really That Bad?

This question has been asked and searched for hundreds of thousands of  times and the answer is…

It’s a very subjective opinion and ultimately depends on you. Your age, health, family, attention to health, medical history, all play a role as will your personal opinion once you’ve experienced it.

Unfortunately, no one can offer you a definitive answer and hopefully the information in this article will provide some clarity of what to expect and allow for an educated decision on whether to come to Chiang Mai or stay during burning season.

How is Air Pollution Measured?

You’ll see two measurements being used. The first is AQI and the second is PM2.5.

AQI stands for Air Quality Index, which is a scale used to measure overall air pollution levels, while PM2.5 refers to “particulate matter” with a diameter of 2.5 micrometers or smaller.

PM2.5 is a key component measured in calculating the AQI and considered one of the most harmful air pollutants due to its ability to deeply penetrate the lungs. 

Here’s a breakdown of the two data points you must consider when analysing your activities outdoors during smoky season in Chiang Mai:

AQI:

• A numerical value representing the overall air quality based on various pollutants like PM2.5, ozone, nitrogen dioxide, etc. 
• Higher AQI value indicates worse air quality. 
• Usually presented with a color-coded system for easy understanding

PM2.5:

• Tiny particles of pollution with a diameter of 2.5 micrometers or less. 
• Can come from sources like vehicle exhaust, wildfire smoke, and industrial emissions.
• Considered particularly dangerous due to its ability to reach deep into the lungs. 

AQI is presented in a numbered and color coded chart like the one below. Remember, AQI includes PM2.5, and there are other tools that can tell you that factor alone which we’ll see later in this FAQ article.

Keep these colors in mind as we see maps and measurements coming up.

Why are PM2.5 Particles Harmful?

Due to their fine particulate matter measuring 2.5 microns or smaller these particles can:

• Penetrate deep into the lungs and bloodstream.
• Cause respiratory and cardiovascular issues.
• Aggravate pre-existing conditions such as asthma and chronic obstructive pulmonary disease (COPD).
• Increase risks of long-term health issues, including lung cancer, atherosclerosis, and cognitive decline.

Short term effects may include bleeding noses, coughing, trouble breathing, itchy and red eyes, discoloration of the eyes and skin, general malaise, headaches, and fatigue.

How Bad is the Air Pollution In Smoky Season?

Air quality during the smoky season can reach hazardous levels, with PM2.5 readings often exceeding 200 µg/m³ or even 400 µg/m³ in extreme cases. These levels are far above the World Health Organization’s safe limit which recommends PM2.5 levels should not exceed:

• 25 μg/m³ in short-term exposure
• 5 μg/m³ for long-term exposure

During peak smoky season, PM2.5 levels can reach up to 364 μg/m³ (AQI of 409) or higher.

To give you a stark contrast, here is Chiang Mai during the non-smoky season versus the heart of smoky season:

Locals measure the severity by whether we can see the mountain Doi Suthep or not. If you can’t, then you know the air pollution levels are extremely bad and any outdoor activity should be avoided.

Who is Most at Risk?

When considering a trip to or settling down in Chiang Mai, please consider if any of you or your family falls into one of these groups:

• Sensitive Groups: Children, the elderly, and individuals with respiratory or cardiovascular conditions.
• Outdoor Enthusiasts: Those who enjoy outdoor activities can be exposed to high levels of outdoor air pollution for extended periods.
• Pregnant Women: Long-term exposure can affect fetal development.

When Does Smoky Season Start and End in Chiang Mai?

This information is really useful to decide when you want to visit Chiang Mai and if you live here, the best time of year to consider living elsewhere.

• Start: The burning season generally begins in January or February when PM2.5 levels start rising. However, localized burning might begin as early as October.
• Peak: February to April is typically the worst period.
• End: By late April or early May, seasonal rains often help clear the air but the pollution can last until end of May

When Is The Smoke The Worst? Which Month Has The Worst Air Pollution?

You can see some historic data records here and as you can see some smoke seasons are better than others and some months are better. But, this changes year on year.

If there’s one month to try to avoid visiting Chiang Mai due to the burning season, it’s clearly March.

How Can You Protect Yourself and Your Family During Smoky Season?

Tips to Protect Yourself from Air Pollution in Thailand

1. Monitor Air Quality (AQI and PM2.5 Levels):
   Use websites like iQAir or AQICN to stay updated on air quality. For convenience, download the iQAir app onto your phone.
2. Limit Outdoor Exposure:
   On days with poor air quality (150 AQI+), stay indoors with windows closed and use air purifiers to keep your indoor air clean. While you may think the malls are a safe place to go, many people each year have taken indoor AQI measurements and none of the malls have clean air making them not ideal places to go to escape the pollution.
3. Use Air Purifiers:Invest in an air purifier suited for your room size. They help reduce indoor air pollutants, especially when outdoor air quality is hazardous. See our recommendations for air purifiers below.
4. Seal Windows and Doors: Prevent outdoor air from entering by using weather stripping or tape.
5. Wear a Proper Mask:
   Use respirators like N95 or KN95 masks when venturing outside. These provide better protection than regular masks. The masks sold at 711 will NOT suffice. See our recommendations for best masks for adults and children below.
6. Carry a Portable Air Quality Monitor:
   Portable monitors can help you identify pollution hotspots, such as busy roads or areas near street vendors, allowing you to avoid them. We also have recommendations for these below. 
7. Make Sure Your Hotel Room Has An Air Purifier: Unfortunately hotel booking sites like Agoda won’t identify if a room has an air purifier, so it’s very important that you ask. It is NOT standard practice to have one and personally, I wouldn’t stay in a hotel or an AirBnB that didn’t. Your room will be your only escape from the smoke so you’ll 100% want clean air.

Can I Escape the Smoke by Traveling Near To Chiang Mai?

Unfortunately, no. The pollution is regional, not urban-specific. Traveling to nearby towns like Pai or Chiang Dao often means encountering similar or worse air quality.

Where Can we go to Escape the Smoke or Avoid it?

If wishing to stay within Thailand, please consider that the smoke is not a localized issue. It affects between 60-70% of the country. You will need to go really far south for green or what you deem to be clean air.

As can be seen by this map, Bangkok, Pattaya, Hua Hin and even sometimes Phuket are not far enough south.

The yellow arrows indicate the wind pattern of North Easterly winds that will carry the smoke and air pollution across the Gulf of Thailand all the way to Koh Samui, Koh Tao, Koh Panghan and even Phuket.

As you can see here in the map below, how prevalent dangerous levels of PM2.5 and hazardous AQI levels are across much of Thailand.

Ultimately, you will have to determine what is an acceptable AQI level for you, but it’s clear that the Northern regions of Thailand have the worst air quality.

So Where Do People Go During Burning Season?

Many people are now choosing to leave Thailand completely during the burning season due to the pollution being nearly inescapable. Some popular destinations are the Philippines, Taiwan, Indonesia, and Malaysia.

Within Thailand, many choose islands in the Andaman Sea. Other popular islands to escape to are Koh Samui and Koh Panghan (even though there is still a risk of the air pollution being carried by the winds in the Gulf of Thailand). 

Many families also love Hua Hin or Pattaya, but having been there a number of times myself, the AQI levels are typically above 150 even with the sea breeze.

What Do People Do All Day If They Can’t Go Outside?

Well, not everyday is awful! Also, it’s a subjective choice for most people whether to go outside and go for a walk, a cycle, a run or play football. Most people just carry on as normal.

However, if it’s one of those days where you could quite literally be breathing in the equivalent of 10 or more packs of cigarettes a day, what can you do?

Watch Netflix, clean your house, have friends over for a hazardous AQI indoor fun day! There are a few cafes that have air purifiers that you may consider. Some gyms and fitness centers have air purifiers too, but be careful working out when AQI is above 150.

You’ll also find yourself eating a lot and most people order food in with Grab or have groceries delivered to avoid going out.

Is Your Pet’s Health At Risk During Burning Season?

While this factor isn’t often talked about at all in the online forums, there is most likely a respiratory health impact on your pets making it equally important that you keep them inside in an area with air purifiers.

Small pets should have a small portable air purifier next to their cage as well.

Is Anything Going To Change? Will The Government Do Anything To Stop Smoky Season?

Although there is growing awareness and stricter regulations on burning practices, progress remains slow. Regional collaboration and sustainable farming practices are essential for long-term improvement and there are policies and bans in place, however the bans are proving difficult to enforce.

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What Are Common Myths About The Smoky Season?

• Myth: “It’s just fog.”
  Fact: Haze may appear similar to fog but contains dangerous particulate matter harmful to health.
• Myth: “Masks don’t help.”
  Fact: Certified masks like N95 and N99 significantly reduce exposure to harmful particles.
  
• Myth: “You only need to worry if you have symptoms.”
  Fact: Long-term exposure has cumulative effects, even for healthy individuals.
  
• Myth: “Chiang Mai doesn’t have a mountain.”
  Fact: There IS a mountain! You just can’t see it for 2-3 months out of the year.

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