The Burning Season

Northern Thailand in March and April

I look out my window and it feels like a grey, rainy day but it isn’t. If I stick my head out and look straight up and can see blue sky directly overhead, but I can’t see Doi Suthep at all if I look straight ahead and it’s a mountain. The source of the grey isn’t rain or fog or mist; it is smoke. The month is March and it is the burning season here in northern Thailand.

In most of Thailand there are two seasons; dry and green. In northern Thailand a third season is observed called the cold season which is from November to the end of January roughly. And then there is a fourth, unofficial “season”, between the end of the cold season and the start of the green; the burning season. In the dry and cold seasons it doesn’t rain at all really and so the air is as dry as a bone and so is the ground by March. March is when the farmers begin to burn the stubble to ready their paddies for the upcoming green season. Wildfires occur both as a result of these controlled burns and due to natural causes as well.

Slash and burn practices by hill tribes get a lot of blame for the smoke, but in Chiang Mai and Chiang Rai provinces most of the hill tribes have been moved away from that style of agriculture. That said, the burning isn’t just localised to northern Thailand but occurs in neighboring Myanmar and Laos as well, where slash and burn agriculture is still practised by many groups. Smoke doesn’t care much about international borders.

But a large part of the burning that is done in SE Asia in general is done by developers who are more than happy to allow indigenous farmers take the heat. Developers are seeking to clear land illegally; once the land has been burned who is to oppose the development? In Indonesia in 2015 people seeking to clear rain forest to develop palm oil plantations were major culprits in the regional smoke crisis of that year.

The topography of northern Thailand is such that the valleys that are home to the cities act as heat sinks and trap both the heat that rises up from the plains in the south and smoke from the massive amounts of burning in the region as a whole. The combination is nasty.

March and April, in Thailand, are the summer months, the July and August of Canada. Thailand is a hot country to start with but in these months, just prior to the first rains, the heat is special. High 30’s and 40’s become the norm. Further north from Chiang Mai in Mae Hong Son, the temperatures breached 50C last year. There isn’t any humidity really at this time of year either. It is just straight up hot.

When you combine this with the smoke, things get ugly. Two years ago I tried to stick it out but on one particularly bad day when Doi Suthep was totally obscured by smoke, I decided to do a little comparison of AQI’s or Air Quality Indices. An AQI measures many different aspects of air quality to arrive at a score which indicates clean air, with a score of 100 and above being considered dangerous. Generally the number that draws the most attention is the PM2.5 rating. PM2.5 particulate is extremely fine and is considered to be the most dangerous to be breathing regularly.

I checked Bangkok’s downtown air quality and it was reasonable; in the 80’s and below the danger threshold of 100. Next I checked Beijing, famous for its pollution. It was much higher than Bangkok, in the 180’s. Dangerous stuff but nowhere near the score that came next – Chiang Mai. The AQI for Chiang Mai at that time was 283 – worse than Beijing by far. Chiang Mai has a population of about 1 million in the greater metro area by the way, compared to Bejing’s 30+ million and Bangkok’s 10+million. The air was poisonous. I was in Phuket (AQI of 8) the next day and for the next few weeks.

Phuket is not always able to avoid the haze either though. In late 2015, one of the largest clouds of haze ever seen stretched from Sumatra in Indonesia over 1,000 km north to Phuket. This is the equivalent of a fire burning in Charleston, South Carolina choking the inhabitants of Ottawa or the citizens of London having the same reaction to a fire in Marseilles, France. These fires are big.

Haze from Sumatra, over 1000km away, in Phuket, October 7 2015

When I came back to Chiang Mai a few weeks later, I got on my motorbike which I had left at the airport and drove home. It was night time so when I turned on the lights I got a bit of a surprise; my hands were covered, thick, in greasy black soot from the motorbike handles. This was the residue from the air settling on the bike over the previous four weeks. This is what I am breathing right now, I thought. I smoke cigarettes and the thought still made me sick. It took twenty minutes of scrubbing to get my hands clean.

The thing is, for the other ten or so months of the year it’s beautiful up here; cool at night and hot in the day. Fresh mountain air only a short motorbike trip out of town. Even during the monsoon season it avoids the worst that the south gets. It will rain for a short time consistently but it avoids the day after day torrential downpours the south gets.

But during the burning season it isn’t a good place to be. Travelers with respiratory or cardiovascular concerns should think twice about coming to northern Thailand in March or at the very least speak to your doctor about what type of effect a high PM2.5 ratings could have on your condition. I’m not a doctor but as I write this we are currently rocking a PM 2.5 level of 156 which is unhealthy for even people without respiratory health concerns (see below).


(The above screen capture is from the following link and can be used to check on the AQI in Chiang Mai and other cities throughout the world.)

The only good thing about the weather in March in Chiang Mai are the sunsets. They are spectacular due in large part, as in Los Angeles I’ve heard, to the smoke.

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