I am reposting this brilliant graphic from www.chiangmaiair.org because it illustrates a few points crucial for an effective campaign to clean the air in Chiangmai.
This image, from NASA’s Fire Information for Resource Management System (FIRMS), shows a high concentration of fires in northern Myanmar and northern Laos, substantially fewer in northern Thailand and southern China. The border between northern Thailand and its neighbors appears to demarcate fire density pretty well.
This image is from a day when Chiangmai had good air quality. But if the fire distribution shown here is typical of our burning season, then we are seeing a regional issue. This conforms to my experience of smoke in other parts of southern Asia at this time of year.
Perhaps we could offer the Chiangmai authorities some guarded praise for their work so far, and consider promoting solutions to the problem at a more regional (i.e ASEAN) level.
It would be interesting to consider a FIRMS time series for this area, and to review literature for references to seasonal smoke in previous generations, as it has likely been an outcome of paddy rice and swidden (slash and burn) agriculture in SE Asia for many generations.