In recent years, the concentration of suspended particles in the atmosphere of Tehran has been increasing. Therefore, we see more polluted days in this city. This situation has had economic, health, welfare, social and negative effects. In this study, we want to investigate the seasonal changes in particle concentration, chemical composition and aerodynamic Distribution in Tehran. Atmospheric Matter sampling was performed in four seasons in 2020 to 2021. Sampling was performed by Andersen Cascade Impactor 8 stages. Also, in each period of sampling process, samples were prepared to study the physical and chemical properties by SEM method. The particle surfaces with magnifications of 5000x, 10000x, 20000x and 50000x were studied. The EDS method was used to study the chemical composition of Particulate Matters. The results show that the north and northwest of the region are affected by the prevailing wind and a large volume of Particulate Matter produced by fixed and moving pollutants move to these areas. The highest and lowest concentrations of total PM collected in Azadi square and Hakimiyeh were 162.11±16.5 µg/m3 and 139.21±12.22 µg/m3, respectively. Also, the Distribution of Particulate Matter in the western and southern regions of the region was more towards coarse particles, while the Distribution of particles in the eastern and northern regions was more towards smaller particles. Due to the geomorphological characteristics of the region, the production of Particulate Matter should be controlled and monitored by moving and fixed sources, to reduce the destructive effect of particles on the health of people living in the region.

BACKGROUND AND OBJECTIVES: Agriculture significantly contributes to global economies, yet it concurrently generates waste in the form of crop residues. Conventional waste disposal methods, such as open burning, contribute to atmospheric Particulate emissions, impacting air quality regionally and potentially globally. Exposure to these pollutants poses substantial risks to human health, including respiratory illnesses, cardiovascular diseases, and premature mortality. This study aims to assess the environmental implications of biomass waste combustion in Yogyakarta, Indonesia. Additionally, the study aims to investigate potential enhancements in biomass burning practices through experimental campaigns conducted in both open and closed burning conditions.METHODS: The study evaluates Yogyakarta's regional air quality using data from the Meteorology, Climatology, and Geophysical Agency for the period spanning from 2020 to 2022. Emission factors from open and closed burning practices are assessed using an experimental furnace equipped with real-time combustion parameters monitoring, including temperature, Particulate Matter concentration, and oxygen and carbon dioxide levels. The openburning experiments involve various combustion conditions for bagasse, leaf litter, and rice straw, encompassing variations in ignition location, initial mass, and air supply methods. Closed burning experiments explore variations in reloading frequency, air-fuel ratio, and air staging.FINDINGS: Yogyakarta's air quality assessment involves comparing rice harvest trends with atmospheric Particulate Matter concentrations during 2020-2022. Open burning practices in Yogyakarta exhibit a correlation with heightened rainfall, which in turn leads to higher emissions from April to August due to reduced rain frequency. Experimental campaigns have revealed that open burning practices result in a significant amount of emissions, ranging from 3 to 29 grams of Particulate Matter per kilogram of biomass.. Meanwhile, the utilization of closed combustion systems has been demonstrated to decrease the emission factor within the range of 0.37 to 1.98 grams of Particulate Matter per kilogram of biomass. This highlights the importance of operating conditions altering Particulate emissions. Moreover, the emission reduction by factor nine, emphasizing the efficacy of controlled combustion techniques in comparison to open burning methods, in mitigating Particulate emissions.CONCLUSION: The study identifies that greater initial biomass mass, mid-ignition, and natural airflow contribute to lower emissions in open burning practices. o achieve optimal closed combustion conditions, it is recommended to reload biomass more frequently with100 percent excess air allocation, distributing 30 percent to primary air and 70 percent to secondary air. These findings not only propose better practices for disposing of agricultural waste and minimizing air pollution but also emphasize the potential of utilizing biomass waste for energy conversion.