ارزیابی ریسک فلزات سنگین در ذرات معلق (PM2.5 و PM10) انتشار یافته از یک کارخانه سیمان واقع در بجنورد، ایران

The present study is an attempt to investigate the heavy metals (Nickel and Chromium) existing in various types of particulate matters (PMs) emitted from a cement factory located in Bojnord-Iran. The research specifically focused on the improvement of health and environmental indexes thus, this research purposed to evaluate the contamination levels and spatial distribution of PMs for estimating cancer and non-cancer risks owing to the exposure of heavy metals in the residents surrounding the cement factory. For this purpose, three main axes with nine stations were determined by considering the wind prevailing and the location of electrofilters and mills in the cement factory for comparing heavy metal contamination levels in both PM2.5 and PM10 pollutant. The obtained results proved that PM10 concentration is much higher than PM2.5 in all points especially the stations located on the third axis. Moreover, it can be concluded that some processes such as the abrasion of raw materials in the cement production line had the largest contribution to the production of PM10. According to the results, cancer and non-cancer risk values attained for Cr and Ni in all stations were in the negligible range, indicating no health risk exists in the present situation. However, controlling and monitoring PM levels in the area are still required to prevent destructive impacts in the future.

Air pollutant emission from the industrial sectors has become a serious challenge worldwide, especially in developing countries (Su et al. 2022; Yang et al. 2023). A variety of industrial air pollution sources such as fossil fuels-based power plants, chemical industries, metallurgy, machine-building, mining, etc. irreparably change the environment and pose significant health risks to surrounding residents (Syah et al. 2021; Mohajeri et al. 2022, Cao et al. 2021). Among these facilities, the cement industry is very important due to its decisive role in the development of the world economy and has attracted the extended attention of many scholars in recent years (Kim et al. 2022; Bogush et al. 2020; Wu w\et al. 2023). The cement sector is the third largest industrial source of pollution, emitting more than 500,000 tons per year of greenhouse gas (Habert et al. 2020). In addition to carbon emissions that lead to the increase in global warming, this sector emits particulate matter that carries various pollutants including, heavy metals (HMs), Sulfur dioxide, and Nitrogen dioxide (Adeyanju et al. 2019; González-Rocha et al. 2023). Therefore, due to the proximity of cities and residential areas to these units, continuous monitoring of these pollutants is undeniable.
Among these pollutants, HMs such as Pb, Ni, Cr, As, Cd, Al, etc. have been recognized as one of the most significant health concerns in recent years due to their widespread presence in the atmosphere and high toxicity (Adegunwa et al. 2023; Lee et al. 2022). The mechanism of action of heavy metals is very complex, and the lack of metabolism of these metals affects not only human health but also the structure of the ecosystem (Karbassi et al. 2016; Turkyilmaz et al. 2020; Pandey et al. 2014). HMs enter the body directly through the inhalation of polluted air or indirectly through the food chain and cause various diseases and complications in citizens' immune system, especially children (Tsai et al. 2019). However, the study of heavy metals' behavior and destructive impacts of their release in different cement production units is still limited (Cui et al. 2022; Ahmed et al. 2023; Liu et al. 2019).

Health risk assessment is currently considered an effective tool for identifying the hazards of HMs, assessing the risks posed to health hazards, and determining appropriate mitigation, control, and compensation measures. Hence, many research efforts have been focused on the human health risk assessment (Rauf et al. 2021; Jafari et al. 2019; Olatunde et al. 2020; Etim et al. 2021). For example, Goudarzi et al., compare the health effects of HMs for citizens in different urban areas. Based on their results, the areas close to industrial sectors have a higher health risk than high-traffic urban areas (Goudarzi et al., 2018). Zhou et al. identified the health assessment of trace elements in different parts of particulate matter (PM2.5 and PM10) in industrial areas in China. The obtained results showed that particulate matter (PM) in places close to industrial areas is associated with a wide range of toxic trace elements, especially chromium, cadmium, and nickel, and carries significant health risks for humans (Zhou et al., 2020).

Alfaro et al. analyzed the concentration level of Ni, Cr and Pb in areas contaminated by slag from an abandoned steel plant in Havana, Cuba. Based on the results, even with negligible Cr concentration, it leads to agricultural food contamination and increasing cancer risk for residents (Alfaro et al. 2022). Mallongi et al. evaluated the levels and spatial distribution of fine particulate matter surrounding the cement industry in Indonesia. Furthermore, they assessed cancer and non-cancer health risks for residents based on the United States Environmental Protection Agency (EPA). They found that, health risks of residents in the studied area are considerably dependent on exposure duration and pollutant concentration (Mallongi et al., 2023). According to the aforementioned literature review, health risk assessment as the most suitable methods has been successful in monitoring HMs in various industrial activities and it can overcome the uncertainty related to their harmful effects.

Our aim in this research is to investigate the amount of heavy metal pollution bound to particles including nickel (Ni) and chromium (Cr) in different locations of a cement factory in Bojnord-Iran. In addition, special emphasis is placed on the use of health risk assessment in determining the effects of chromium and nickel contamination. For this purpose, sampling was performed in order to determine the concentration of studied heavy metals in PM2.5 and PM10 in 9 stations.

The contamination level and health risk assessment of HMs existing in various types of particulate matters (PMs) emitted from a cement factory in Bojnourd (Iran) were studied. In this regard, sampling from 9 stations in three axes was conducted to analyze the concentration of Ni and Cr ex