Swidden Agriculture around Chiang Mai

Chiang Mai is currently in the midst of its seasonal grip of airborne pollution from widespread fires & car omissions.

This pollution creates rampant respiratory illness throughout Thailand's north as seasonal burning combined with hotter weather and an earlier-than-usual summer is bringing suffering to large numbers of both residents & visitors alike.

The majority of the problem originates within the farming populations of Northern Thailand, Myanmar, Laos & Cambodia.

Each year from February until the end of March the farmers clear large areas of land & forests by burning , they do this as a part of the “swidden” agriculture(slash & burn) which is still traditionally heavily practiced within these areas as preparation for new crops or just for creating new grazing areas for their livestock.

Another source of the problem are the many smaller forest fires set by the villagers clearing areas for the cultivation of wild mushrooms deep within the forests.

The third part of the problem is the large number of older cars & trucks on the roads all around the north of Thailand they are adding to the problem rather than being the main cause by the high omissions of pollutants they exhale !.

Add to that a city (Chiang Mai), that is surrounded by mountains, has virtually no winds or rain this time of year, and you have a perfect recipe for old fashioned SMOG !.

Chiang Mai residents, especially the elderly, children and people with respiratory problems, are currently being advised to avoid outdoor activities as the city's air pollution is starting to reach dangerous levels.


The problem is created by the dust particles that are omitted from the burning fires.

It's NOT the large pieces of black ash that fall from the sky, it’s the dust particles smaller than 10 microns( PM-10) that are measured & do the damage.

They can easily enter sensitive internal breathing organs and cause respiratory ailments.

The recognized worldwide measurement of this pollution is “microgrammes per cubic metre (ug/cu m)”.

Chiang Mai is currently ranging between 95 - 110(ug/cu m),the Thai Pollution Control Department has set the ’safe level’ to be anything less than a PM-10 of 120.

By comparison in the U.K., the United States and the European Union as a whole it is considered a serious pollution ‘episode’ if the PM-10 level exceeds 50.

By way of a guide to the readings of other major countries around the world, the W.H.O.(World Health Organisation) provided the following annualized average readings :
Sweden - 13
France - 15
United Kingdom - 19
Germany - 22
Malaysia - 24
United States - 25
Thailand - 76
China - 87
Indonesia - 102
Chiang Mai - 49.85 annualised
Chiang Mai – averaged throughout March 2007 161.7


To give you an idea of EXACTLY how bad it can get in Chiang Mai, on 14th March 2007 the PM-10 levels reached 303.9 - catastrophically high by any standards !.

In response to the problems, the environmental office has opened a call centre to update local air quality reports for residents and concerned agencies.

Tambon-level emergency response units have also been set up to crack down on burning activities, which could worsen Chiang Mai's air pollution.

Despite Chiang Mai's pollution in theory being within 'acceptable' health-standard limits, hundreds of Chiang Mai residents are going to hospital for treatment as they are suffering from the pollution-laden smog.

The only way that Chiang Mai residents have been able to escape this problem is to physically move to other provinces further south until the airborne threat disappears.

The only way to disperse this air pollution is by either rain or wind, IF by the end of March it has not rained, the Thai military takes over & releases cloud forming chemicals from planes that then bring welcome rain & relief to all beneath it !!.