Abstract
Iran is located in the global dust belt, and thus, due to global warming, drought, and land use changes, dust has become more severe in the last two decades and dust storms have moved towards the western and southwestern borders of Iran. In the meantime, Ilam province is one of the areas exposed to dust in Iran due to its geographical location and hot and dry climate. Accordingly, in the present research, the temporal and spatial trends of dust storms during a long-term period (2001-2023) in Ilam province have been studied. In this regard, MODIS aerosol optical depth (AOD) dataset was used to measure dust changes, and Google Earth Engine (GEE) processing capabilities were used to perform analyses. Based to the findings, the dust phenomenon has a different temporal trend and in general, the highest frequency of dust events in the region occurred in the summer months. Furthermore, the evaluation of the spatial trend of dust has determined that the southwest and west of the province, which corresponds to the boundaries of Dehloran and Mehran cities, have the highest density and intensity of dust, which is caused by desert dust and originated from its local and foreign hotspots. The research results show that dust is one of the main environmental hazards of Ilam province and has the ability to damage its socio-economic and infrastructure structures. Hence, planning in this field should be focused on comprehensive plans for land use and adopting crisis management measures in order to deal with the effects of the dust crisis.
EXTENDED ABSTRACT

Introduction

Air pollution has been one of the key issues of environmental studies in recent years, and researchers have specifically addressed dust storms and their consequences. Accordingly, Iran is one of the areas exposed to dust storms, which is located in a region known as the dust belt. Due to its proximity to three major sources of dust production (the deserts of Iraq, Syria and Saudi Arabia) in the west, Iran has always faced dust storms and their sequences. Hence, it can lead to adverse environmental, social and economic consequences, especially in the dry areas of southwestern Iran, and cause problems in human activities such as agriculture, transportation, industries, social services and medicine. In this regard, Ilam province is located at the southwestern Iran, which recognized as one of the major dust-prone areas in the country. In recent years, Ilam has suffered significant damage from dust storms of desert origin. Hence, the dust phenomenon has had significant socio-economic and environmental effects on the daily life of residents. Thus, the present research has been carried out with the aim of evaluating dust patterns as one of the major environmental hazards in Ilam province.

Materials and methods
The purpose of this applied research is to monitor and evaluate the temporal and spatial trends of dust storms in Ilam province. In this regard, the time period of the current research includes a long-term statistical period from 2001 to 2023. In the current research, various features of Google Earth Engine (GEE) platform have been used. Besides, MODIS monthly mean time series images have been used to analyze dust events at the regional level. Particularly, the use of aerosol optical depth (AOD) using MODIS images is highlighted as one of the precise methods of dust monitoring in this research. Dust time series data were extracted from MODIS MCD19A2.061 products with a spatial resolution of 1000 meters, and we have done the processing. In addition, hotspots of dust storms have also been identified using the auxiliary method of visual interpretation of MODIS images. Therefore, in this research, the monthly average time series of MODIS images with true band composition (bands 1, 3 and 4) from 2001 to 2023 has been used to visually identify dust sources in Ilam province.

Results and discussion
According to the findings, the highest frequency of dust storms occurred in 2008, followed by 2022, 2009 and 2005, and the region witnessed the most dust storms throughout the year. On the other hand, in some years such as 2019 and 2020, the frequency of dust storms is low, and in some months of the year, there are hardly any dust storms and in some months, practically no dust storms have been recorded. Furthermore, the dust phenomenon has a different temporal trend and in general, the highest frequency of dust events in the region occurred in the summer months. Moreover, the evaluations have determined that between November and January, the study area suffered from the least frequency of dust, which due to the fact that rains and mainly snow prevails in the region during this period, so it can be caused by the role of climate and rainfall. to be in the relative control of the dust storm. In terms of spatial distribution, the dust density is different in different parts according to its general distribution and other factors such as the origin of the dust, its extent and its constituent particles, and its minimum and maximum values have shown differences. In this regard, the southern parts of the region, especially the area of Dehloran county, have received the highest dust density most of the time. The main sources of dust storms are also located in its southwestern areas and within the boundaries of Dehloran county. From this point of view, the findings have determined that the sources of dust in Ilam province correspond to desert areas and a large part of this province is exposed to dust storms of desert origin.

Conclusion
Dust is one of the main environmental hazards of Ilam province, and both local and external sources have played a large role in its frequency during the last two decades. In general, the results have shown that the main sources of dust in Ilam province are, firstly, dried up water bodies in the territory of Iraq, and secondly, the deserts located on the border of Iran and Iraq inside the province. Hence, the socio-economic and environmental effects of dust in Ilam province and especially its border areas have been quite noticeable. Therefore, dealing with this hazard must be strictly followed, and this requires the adoption of comprehensive land use plans to manage the dust crisis in its various stages.