Investigating the ratio of PM2.5 to PM10 particles concentration in Tehran city and compiling an index for the occurrence of dust

Abstract

Suspended particles are known as one of the most important and common pollutants worldwide. Since dust storms are related to suspended particles, the current research examines the ratio of the average concentration of PM2.5 and PM10 suspended particles and determines an index for the occurrence of dust. In this research, the concentration data of PM2.5 and PM10 particles in 3 monitoring stations of Tehran Air Quality Control Organization (Taribat Modares, Pirouzi and Sharif stations) in the years 1396-1402 (2018-2023) have been used and by extracting AOD data from the site Giovanni and the determination of dust days and finally compared to the data of the Barcelona Regional Dust Center to ensure the correctness of dust days. The results show that the average concentration of PM2.5 and PM10 and the ratio of PM2.5/PM10 on days with dust is higher than this value on days without dust. The daily changes in the average concentration of suspended particles in the selected stations show that in most cases the changes in the concentration of suspended particles are similar and both increase and decrease together, but the amount of changes was not the same. According to the origin of the production of suspended particles, their ratio can be used to determine the dust index. The emission of large suspended particles mostly comes from natural sources and fine particles from secondary reactions of the atmosphere and human activities. In most days, the average concentration of suspended particles PM10 of the station is higher than the amount of Dust obtained from the data of the Barcelona Regional Center for Dust, because the air quality measuring stations measure the amount of suspended particles emitted from natural and man-made sources together, but the data of the Regional Center for Dust Barcelona shows the amount of dust. From the PM2.5/PM10 ratio, it can be concluded that there is dust if this ratio is less than 0.4.