A massive fire engulfing vast areas of a Chiang Rai forest has intensified the smog problem in this northernmost province, adding to the country's pollution woes.
For more than a month, many people in parts of Chiang Rai have put up with hazardous air pollution presumably linked to monoculture corn farming that see some local farmers, along with others in neighbouring countries, resort to illegal open burning to get rid of farm waste.
Rugged terrain makes it difficult for firefighters to tackle the blaze that began early this month.
A senior army figure said the fire bore similarities to a recent blaze in Doi Luang Chiang Dao in Chiang Mai, which was man-made.
Some Chiang Mai-based activists believe land conflicts could be behind the huge fire that destroyed the vast Doi Luang forest area.
While the cause of the Chiang Rai fire is still being investigated, it is believed some farmers may have lit the fire to clear forest land to expand maize cultivation -- a practice common in other northern provinces including Chiang Mai.
Several Myanmar and Lao farmers were found to have encroached on forests to enlarge their farms.
Open burning is a common practice for them to quickly get rid of scrub at the end of the harvesting season from February to April, and fires like these can get out of control.
Greenpeace this week pointed to a growing transnational food industry which encourages the expansion of unsustainable monoculture corn farming in Thailand, Myanmar and Laos.
Due to higher demand in China and Thailand, maize offers an attractive price -- a key factor that draws farmers and results in seasonal smog, the environmental group said
Tara Buakamsri, country director for Greenpeace Thailand, said tighter regulations are needed to put an end to extreme air pollution that endangers the health of local people.
The Pollution Control Department (PCD) recently said the northernmost city of Mae Sai in the past month has been blanketed almost every day with extremely high levels of PM2.5 -- the ultra-fine particulate matter that is less than 2.5 micrometres in diameter and which burrows deep inside lung tissue.
The department recorded high level of dust measuring no less than 90 micrograms (mcg) per cubic metre, while the 30-day average stood at 169mcg and the highest PM2.5 level was 452mcg.
The country has set a safe level for PM2.5 at 50mcg, double the world standard.
Forest fires are a part of the North's ecological system as some species, for example teak, require a small fire to help crack the seeds.
But effective fire management is needed and firefighters must be better equipped to battle huge forest fires.
Volunteers must be properly trained on how to handle a blaze and minimise associated risks.
At the same time, the government should take serious action on regulating transboundary corn cultivation.
It must do whatever it can to secure cooperation from Nay Pyi Taw in Myanmar and Vientiane in Laos, as well as get the private sector involved in working together so more farmers in the region pursue sustainable corn farming.