If one visits Chiang Mai during most of the year, it is a great city, but during February, March and April it is awful. The atmosphere is polluted to a level TEN TIMES above the USA safety level. This is due to a combination of factors; farmers in Thailand and the surrounding countries burning rice stubble during late February, March and early April, illegal forest clearance (slash and burn) for either short term crop gain or in some cases development, and forest fires started by lightning and, believe it or not, arson.  Temperature inversion, similar to that found in the Los Angeles basin and lack of prevailing winds makes matters much worse in Chiang Mai city itself, hiding even the famous Doi Suthep which stands 1600m high and only two or three kilometres from the edge of town.

It happens every year according to magazines and locals, and although there is always an outcry, nothing is done about it as the polititians prefer to make headline grabbing noises and then go quiet as soon as the rains come and solve the problem for another season. Many people die or suffer serious respiratory illness during this period due to the pollution and some long term residents who have the choice leave for anywhere with cleaner air, although northern Laos and southern Myanmar are also badly affected.

Sadly, this is not an option for working people and those with families, but tourists, particularly those with allergies or breathing compaints, should take note and travel elsewhere from mid February to mid April. Local magazines, websites and YouTube (Thaivisa and 2012 Chiang Mai Smoke) contain many articles and photos about it but of course as a visitor, the first you'll know is when you land in a "fog" and then step out of the airport and smell the air.  Google will produce a lot of useful information as to how this may affect your health too.

CM Trip Smog 

This serious situation will require a great deal of political will, education and international co-operation if it's ever going to get better and the only way it will receive the attention it merits is if the travel industry can put some pressure on the people who can make a difference.