Air-Pollutant Emissions from Agricultural Burning in Mae Chaem Basin, Chiang Mai Province, Thailand

Abstract

Particulate pollution is a continual problem which is usually caused by the burning of crop residues in highland agricultural systems. The objectives of this study are to investigate crop-residue management and estimate the amount of pollutant emissions from burning crop residues for each land-use pattern (grain maize, seed maize and integrated farming), and to estimate the chemical compositions of PM 2.5 emissions from agricultural burning in Mae Chaem basin, Chiang Mai Province, Thailand. The purposive sampling method was used for sample selection. A door-to-door questionnaire survey was used to obtain responses from 149 respondents. Greenhouse gas (GHG) emissions from the open burning of crop residues were estimated, using specific emission factors obtained from several literature reviews and from the field by the questionnaire survey. Results revealed that the majority of farmers burned maize residues during April and May and mostly in the afternoon. These burning behaviors are in line with the supportive weather conditions that reflect high values of temperature and wind speed, and less rainfall and relative humidity result in maize residues being burned easily and quickly. The integrated farming system generated the lowest GHG emissions and amount of chemical composition of PM 2.5 emissions, followed by the grain maize and seed maize patterns, respectively. This study strongly supports the implementation of the integrated farming system in Mae Chaem basin. Proactive and reactive measures should be taken in a well-organized and systematic fashion and should engage all related parties. More importantly, there is an urgent need for policy makers to include PM 2.5 concentrations to upgrade Thailand's air-quality index (PM 2.5 AQI).

Analysis of Tropospheric Nitrogen Dioxide Using Satellite and Ground Based Data over Northern Thailand

“…They reported that MODIS-Aqua captured 70% of the fires relative to MODIS-Terra. Arunrat et al [28] presented times of the day for burning crop residues in Chiang Mai. They found that most of the farmers burned the crop residues (67% of grain maize and seed maize residues and 86% of crop residue from the integrated farming system) in the afternoon (12:01-18:00 LT) compared to in the morning (06:01-12:00 LT) and in the evening (18:01-06:00 LT).…”

“…In Thailand, the northern region experiences air pollution haze episodes from forest fires and vegetation fires for land clearing each year during the dry season (January-April). During this period (especially during March-April), air pollutants such as particulate matter with diameter less than 10 micron (PM10), particulate matter with diameter less than 2.5 micron (PM2.5), carbon monoxide (CO), and NO2, have been reported at higher levels compared to other months [26,[28][29][30][31]. The mountain ranges surrounding the northern region create a narrow valley which is perfect for trapping air pollutants over the cities causing even higher levels of air pollutants.…”

Straw Utilization in China—Status and Recommendations

“…Prescribed burning, also known as controlled or planned burns, is the planned and controlled application of fire to a predetermined land area. It is an effective and efficient means for resources management [47,77]. Studies have shown that farmers often burn straws right before the effective date of burning bans or a major snowstorm (e.g., [47]).…”

“…Consequently, widespread burning of the open-field in a day or two hammers the air quality greatly. Furthermore, a survey in Thailand found that two-thirds of farmers burned residues in the afternoon [77] when dry and windy conditions support a faster and more complete burning. Unfortunately, those meteorological conditions also favor the dispersion of air pollutants.…”

“…Adaptation of prescribed burning in agriculture residue management could result in far less impact on air quality in urban centers by allowing farmers to burn the straws during a longer time period when the weather conditions are less contusive to atmospheric mixing and regional transport. This requires incorporation of weather and air quality forecast, including wind speed, air mass directions, temperature, relative humidity, and precipitation [47,77]. Based on this information, prescribed burning could be allotted in some areas (e.g., downwind of a big city) for a specific time period (e.g., a few days), then move on to other areas to ensure on-time completion of burning in the region.…”