Join our list
Love Thailand as much as we do? Join our mailing and we'll send you a free guide to our 30 favorite destinations to discover in Thailand.
The time of year infamously known as Chiang Mai’s smoky season has arrived. Perhaps one of travelers’ biggest worries is planning a trip to northern Thailand and not knowing how bad the air quality is. After living through several of Chiang Mai’s smoky seasons, here’s what you can generally expect during the worst of it and how to handle it.
Chiang Mai’s hot smoky season doesn’t get into full swing until March. However, we’ve noticed the beginnings of haziness as early as January and extending through the middle of May. March and April are the worst!
What Causes Chiang Mai’s Smoky Season?
The smoky season is caused by several different factors, although we can’t say for certain which is the biggest contributor.
Farmers burn fields and brush to get ready for a new season of crops. We’ve driven past farmland just outside Chiang Mai’s Old City and smoke trails can be easily seen from the road. We’ve also seen smoke wafting up from the hills and nearby mountains. Locals also burn their trash, but that is arguably a year-round thing.
Additionally, it’s hard to miss the dark gray smog spewing from vehicles’ exhaust pipes, particularly from Chiang Mai’s songthaews and tuk tuks. When the high season rolls around between October and February, the increased traffic adds to the air pollution.
Chiang Mai is also surrounded by Doi Suthep, Doi Saket, Doi Inthanon, and Doi Khun Tan. These mountains create a valley that traps the dense vehicle smog and crop-burning smoke over Chiang Mai.
And not to be forgotten, the last rainstorm passes through Chiang Mai near the end of October. No frequent rain to clean the air means that by the time it’s March, the land and air are dry and dusty.
What to Expect During Chiang Mai’s Smoky Season
Chiang Mai’s smoky season becomes apparent when its typical robin egg blue skies are replaced by a dingy yellow haze, lack of visibility, and a lingering campfire smell in the air. Nearby hills and buildings are difficult to see and often disappear entirely on bad days. On the worst days the local mountain, Doi Suthep, cannot be seen. Even the sun is muted to a glowing orange ball in the sky.
The smell of smoke lingers in the air. We smell it in the morning when we first step outside or open our windows. When we go out for the evening or line-dry our laundry, our clothes and hair smell like we’ve been around a bonfire.
We also notice that many surfaces develop a thin gritty film on them. Often we can see the dust clouds hanging in the air, which are created by passing cars and nearby construction.
Health Effects of Chiang Mai’s Smoky Season
The dust, dirt, and smoke particles contribute to a poor air quality index (AQI). Particles that are smaller than 10 microns in diameter (PM10 or less) have adverse health effects. PM2.5 particles are considered really harmful. Carbon monoxide, nitrogen dioxide, and sulfur dioxide also contribute to AQI levels. Chiang Mai’s levels swing back and forth between 101-150 (Orange, Unhealthy for Sensitive Groups) and 151-199 (Red, Unhealthy) and 200-300 (Purple, Very Unhealthy).
Chiang Mai’s AQI levels can be viewed in real-time on AQICN.org, although this site doesn’t show seasonal trends or a yearly comparison. For those who are interested in conveniently monitoring the air quality, there’s also an app called Air4Thai that is available for Android and Apple smartphones.
In general, the higher the AQI, the hazier it is and the greater toll it can take on your lungs. Some people may also experience sinus trouble. For others, the smog can cause bronchial inflammation, labored breathing, or an asthma attack.
How to Combat Chiang Mai’s Smoky Season
Many people are concerned with the adverse health effects caused by the increased air pollution during Chiang Mai’s smoky season. Luckily, there are a few options to keep you healthy, both indoors and outdoors.
01 Stay Indoors During Peak Hours
Staying indoors during the hottest times in the afternoon will do wonders for most people. Chiang Mai’s smoky season also coincides with some of the hottest temperatures of the year, so we find ourselves preferring to go out in the mornings and evenings anyways. We keep our windows shut and turn on the fan if we want air circulation in our house.
02 Wear N95 Grade Masks
If the smog is bothersome while you’re outside, wearing face masks with a proper filter grade will protect your lungs and sinuses. Look for masks that specifically advertise a filter grading of at least N95. They should also fit snugly around the nose and mouth with no open gaps on the sides to allow unfiltered air in.
We have purchased masks like this at large department stores such as HomePro or hardware stores featuring 3M products. Masks generally cost around 150 baht (5 USD) each.
These are not the cheap surgical look-a-like masks that can be purchased at 7-Elevens, mini Tescos, or FamilyMarts. Thais wear these thin, white masks during the burning season but they are useless. These masks don’t protect the lungs from the finer particles.
03 Invest in an Indoor Air Purifier
Air conditioning units can filter the air for larger particles such as lint and hair. However, investing in a stand-up air filter for your home or apartment can keep your lungs and sinuses happy indoors. These are designed to trap the smaller particles.
There are many brands on the market. They can be purchased from major home appliance stores and supercenters such as HomePro, but we bought an air purifier online in Thailand and it’s amazing. They are well worth the investment, especially for people who are sensitive to the poor air quality.
We also use this neti pot and nasal rinse to clean out our sinuses from time to time. We bought ours from a small pharmacy at Chiang Mai Gate and use it when the dust and smoke make our noses itch. There are different brands and styles of neti pots, but we prefer the squeezable ones to the ones that work off gravity alone.
04 Enjoy Time in Southern Thailand
Otherwise, you can do what we’ve planned to do and vacation in the southern beach regions of Thailand. We’ve recommended this to others in the past.
Our Experience with Chiang Mai’s Smoky Season
We first arrived in Chiang Mai in March 2013 right as the burning season was kicking into high gear. At the time the sky was hazy and the air smelled like a campfire but we weren’t overly affected by the dry heat or the smoke at the time. We attributed this to being preoccupied with getting settled into our new apartment and being so excited about moving to Thailand.
Every year since then – 2014, 2015, and 2016 – Chiang Mai’s smoky season has seemed to worsen. We’ve invested in face masks with the proper N95 filter grade. Chris notices that his sinuses flare up when he doesn’t use his mask outside or on the motorbike. We also adjust our schedule and stay inside between 2pm and 6pm and avoid outdoor restaurants and cafés completely.
It wasn’t until the rain showed up sporadically in April and a bit more in May that the visibility and air quality improved significantly.
The Bottom Line
Chiang Mai’s smoky season can make you physically uncomfortable and you’ll definitely miss out on the picturesque views. It’s no wonder why tourists are hesitant to visit Chiang Mai during the burning season. Or why locals tend to vacation down south during this time.
We personally do not recommend visiting northern Thailand in March or April. This is especially true if you have breathing problems triggered by air pollution. However, we think most people will enjoy their time here for a few days and as long as they know the limitations of their own body and use caution when outside. After all, we’re sure almost anyone would be thrilled to spend time in Chiang Mai, smoky season or not!