Iranian Journal of

Background and Objective: This study was conducted to investigate the long-term temporal trends and spatial variations of ambient PM₁₀, PM_2.5, O₃, concentrations in Tabriz city during the years 2006-2017.
Materials and Methods: Real-time hourly concentrations of PM₁₀, PM_2.5, O₃ measured at nine air quality monitoring stations (AQMSs) were obtained from the Tabriz Department of Environment (TDoE) during 2006-2017 and analyzed. Spatial and temporal variations of pollutants using the Mann-Kendall's test and Moran’s I index were analyzed.
Results: The results of this study showed that the annual trend of PM₁₀, PM_2.5 was decreasing but remained almost constant for O₃ during the study period. During some of the studied days, PM₁₀, PM_2.5 levels were exceeded greater than the WHO AQG and National standard levels. Moreover, the highest monthly mean concentrations of PM₁₀ in October (80.3 µg/m³), PM_2.5 in January (42.9 µg/m³) and O₃ in June (77.8 µg/m³) were observed. Comparison between the stations indicated that the Raste Kuche station was more polluted than other stations.
Conclusion: Effective control planning and implementation policies are essential to improve the air quality of the Tabriz environment. Hence, information provided in this research can be used as a key step for city managers, policymakers, and health officials to reduce the health impacts of air pollution.

Background and Objective: Street dust, as both a source and sink of pollutants, is considered a reliable indicator for assessing atmospheric pollution. Therefore, this study aimed to evaluate the pollution levels and environmental toxicity of arsenic (As), zinc (Zn), lead (Pb), cadmium (Cd), and copper (Cu) in street dust in the city of Hamedan in 2023.
Materials and Methods: A total of 108 street dust samples were collected from 12 sampling sites, including residential, commercial, and industrial regions, during the spring, summer, and fall seasons. The concentrations of the analyzed elements were determined using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Additionally, pollution indices (PI), integrated pollution index (IPI), and mean effects range median quotient (mERM-Q) were calculated.
Results: The highest average concentrations of the analyzed elements in street dust were observed in the industrial regions and the fall season for As (5.79 mg/kg), Zn (405 mg/kg), Cd (0.758 mg/kg), and Cu (84.8 mg/kg). For Pb, the highest average concentration (110 mg/kg) was found in commercial regions during the fall season. PI values indicated pollution levels for As, Zn, Pb, Cd, and Cu ranging from "moderate" to "very high." The average IPI values varied between 2.52 and 3.90, reflecting "high" pollution conditions across all sampling sites and seasons. Furthermore, the average mERM-Q values suggested a 21% probability of elemental toxicity in the analyzed street dust samples.
Conclusion: The findings highlight the influence of human activities, seasonal variations, and emission source fluctuations on street dust pollution. To mitigate pollution, it is recommended to identify and control the release sources of these elements, particularly in regions with higher pollution levels.