چكيده لاتين
Not all particulate matter causing air pollution in Isfahan is a result of human activities; natural pollutants also play a significant role. The Middle East is one of the five regions with the highest dust production in the world, and Iran, due to its arid and semi-arid climate and annual rainfall that is half the global average, is affected by various local and regional dust sources. This research, using the WRF-CMAQ emission model provided by the US Environmental Protection Agency, has calculated the concentration of ambient dust particles across the country, including Isfahan. The results of this modeling, along with ground and satellite monitoring data, can determine the dust situation in Isfahan. Given that important factors affecting dust emission include weather conditions, soil moisture, and vegetation type, the dispersion of suspended particles that change throughout the year, has been simulated in different months of the year. The results show that in most cases, internal dust sources have the greatest impact on Isfahan. In the months of July, August, April, September, and June, the concentration of PM2.5 particles has exceeded the World Health Organizationʹs recommendations. In the first half of the year, the eastern regions of the Semnan desert and the borders of the Semnan, Razavi Khorasan, and Southern Khorasan provinces, as well as the central desert and Lut desert, have been the most important sources of dust entering Isfahan province. Also, internal sources such as Ardastan, Nayin, and Khur and Biabanak are active in the summer but their impact is less than other sources due to their small size. One of the most important external sources of dust is a desert in western Afghanistan, which in most years affects the eastern and southeastern regions of Iran and sometimes reaches Isfahan. Dust storms from Afghanistan in 1401 increased by more than 70% compared to the long-term average. In autumn and winter, despite more rainfall and higher soil moisture, dust still exists in Isfahan and often comes from the Arabian Desert, Iraq, and Syria. The combination of this dust with pollutants from stationary and mobile sources makes the pollution conditions in all cities of Isfahan province critical. In 2021, the annual share of PM2.5 caused by dust in an area with a radius of 50 kilometers from the center of Isfahan was 19%. The share of particulate matters below 2.5 microns was 38% in summer, which decreased to 9% as the air cooled in winter .In this study, the annual average of PM2.5 particles in Isfahan and its surrounding areas between March 2020 and March 2021 has been calculated, and the related health damages have also been estimated. The amount of health damage caused by ambient dust particles from erosion sources was 115.4 million dollars, which accounts for 26% of the total damage.
