Haze and smoke problems with adverse socio-economic and health impacts have become emerging new “disaster” issues over the last few years, especially in the North of Thailand. The unprecedented smoke haze that blanketed all areas in the northern highland region of Thailand is a recent problem that the local people must endure every year. Moreover, the smoke haze situation directly affects the air quality in many areas, including the provinces of Chiang Mai, Chiang Rai, Mae Hong Son, Lampang, Lamphun, Phrae, Nan and Phayao. Report No.10 from the Office of Disease Prevention and Control stated that from March 15 to March 22, 2007 (Health Information System Development Office, 2012), there were a total of 57,765 patients seeking treatment due to illness related to smoke haze in 8 provinces--Chiang Mai, Lamphun, Lampang, Mae Hong Son, Phayao, Chiang Rai, Phrae and Nan--or a daily average of 7,220 patients during that period of time. Over 90% of cases had general respiratory problems with slight symptoms. The highest number of patients, 18,412 cases, was in Chiang Rai followed by 13,936 cases in Lamphun and 8,399 cases in Chiang Mai respectively. A report from Chiang Rai Provincial Hospital indicated that since 2007, the number of patients was very high, with an average of 2,200 cases per day in March of each year (Khantipong, 2007, quoted in Manomaiphiboon, 2007).
The Particulate Matter of 10 microns in diameter or smaller (PM10) is considered the most significant air pollutant that leads to serious air pollution during the dry season, especially in northern Thailand. Major sources of PM10 are open burning (Manomaiphiboon, 2009; and Rayanakorn, 2010) and internal combustion exhaust from traffic. However, traffic density seems to be constant for the whole year, while open burning, mostly performed during the dry season, is found coincide with the peak of the annual haze episode in the upper northern region of Thailand (Chantara, 2012; Oanh Kim and Leelasakultum, 2011). The open burning in this region consists of forest fires and the burning of agricultural waste. These activities definitely emit a variety of air pollutants in the forms of both particulates and gases. In the case of Chiang Mai, it was discovered that 50% - 70% of PM10 came from forest fires and the burning of agricultural residues, 10% came from diesel engines, and the remainder came from dust that blew over from other sources (Rayanakorn, 2010 and Jiamjai, et al. 2010). According to a report from the Pollution Control Department, the level of PM10 measured at stations in northern Thailand started to rise above the standard level set by the Pollution Control Department (120 µg/m3) from February, with the highest levels of PM10 found in March of each year. Chiang Rai, especially in Mae Sai district is one of many provinces in northern Thailand that is facing very severe air pollution. The PM10 measurement recorded in Mae Sai during February to March 2007 was as high as 158 microgram per cubic meter or 120 microgram per cubic meter higher than the safe level. At the same time, based on the Air Quality Index (AQI), the province’s air quality level was measured at 135, higher than the national air quality standard for the pollutant at 100. The air pollution could affect the health of all people especially
for the risk group i.e. children under 5 years old, elderly people who are 60 years old and older, allergic patients and respiratory syndrome patients. The health report from Chiang Rai Provincial Public Health Office stated that during the mentioned period, there were 2,200 patients with respiratory syndrome admitted at the hospital. The statistic figure was unusually way up comparing to the previous years. Consequently, it was considered the highest ever recorded figure in the northern part of Thailand. Therefore, the government had declared the area “A Disaster Zone” after the haze hit the region in March 20, 2007.
Nevertheless, Chiang Rai had not only faced the problem with burned area locally but also from its neighboring countries. It was found that the neighboring countries had a number of burned areas as well. The burned area in GMS Countries had caused Trans boundary haze effect which covered the whole Chiang Rai. At the present, haze and smoke problems in Chiang Rai are still considered critical. The report from the Pollution Control Department indicated that the maximum 24-hour PM10 value measured at Chiang Rai Station was 357.46 µg/m3 on March 19, 2012. PM10 value at this station was almost three to four times higher than the standard level (Pollution Control Department, 2012). To study the possibility of the impact of the open burning conducted in neighboring countries, the author decided to classify the burned area by analyzing the Maximum Likelihood and Supervised Classification from the multi spectral satellite data as of March 26, 2007 and April 10, 2010 employed by Landsat 5TM. Additionally, daily backward trajectories of air mass arriving in Chiang Rai at an altitude of 500 meters on March 1 to March 31, 2007 and 2010 were calculated using HYSPLIT Model developed by the Air Resources Laboratory of the United States National Oceanic and Atmospheric Administration (NOAA).