The influence of agricultural activity was evaluated through approximate measurements of emissions found in northern, central and north-eastern provinces in Thailand, on both a monthly and yearly basis. These estimations were carried out in agriculture and agro-industry intensive areas, using the following variables: Burning of residuals from harvested crops; forest fires; and related agro-industries on air quality according to province. Monthly emission records of particulate matter (PM) NOx and SO2 and air pollutants were estimated in diverse crops based on documented production levels of commonly harvested items (Ex: rice, sugarcane, and potatoes). Crop types and residue burning schedules were also taken into account, depending on the concerned province. In order to ensure the reliability of projected estimations, inventories evaluated each month were put into comparison with data gathered from air monitoring stations, held under the management of the Pollution Control Department (PCD) in Thailand. Thus far, the sugar processing industry has had the greatest effect on assessed regions due to the burning of sugarcane residue as boiler fuel, as well as its use as raw materials. To confirm this, the backward trajectory analysis of the air mass in upper northern, lower northern, and northeast Thailand was calculated at its PCD station. It was found that the concentration of ambient PM worked in conjunction to forest fires and agro-industrial activities. In contrast, effects concerning air pollution proved to be much less significant.