Assessment of PM₁₀ Atmospheric Particle Concentrations and Heavy Metals Levels in the Air of Gorgan City, Iran

Abstract

Introduction: With increasing industrialization and urbanization, particulate matter (PM₁₀) has become one of the major air pollutants and a critical concern for environmental and public health. Therefore, this study aimed to assess seasonal/annual variations of PM10-bound heavy metals in Gorgan, compare them with WHO/international data, and identify potential sources via correlation analysis. Methods: cross-sectional experimental study was conducted between March 2023 and March 2024 in Gorgan, Golestan province, Iran. Sampling was performed every six days throughout the study period according to the U.S. Environmental Protection Agency (EPA) method. A total of 52 samples were collected to determine PM₁₀ and heavy metals concentrations. Samples were taken from a central urban station using a BGI Omni FT ambient air sampler. Results: Results showed that PM₁₀ concentrations ranged from a minimum of 20.83 μg/m³ in early November to a maximum of 277.78 μg/m³ in early February, with a mean ± SD of 69.3 ± 49.82 μg/m³ across the study period. Seven trace elements were analyzed, and their annual mean concentrations followed the order: Cd <Co < Cr < Ni < Cu < Pb < Zn. Strong positive correlations were observed among several metals, particularly Cu, Cr, and Ni, with nearly linear relationships. Conclusion: The findings demonstrated that PM₁₀ levels in Gorgan slightly exceeded the WHO 24-hour guideline, with more pronounced fluctuations on a monthly scale. Among the heavy metals, Zn, Pb, and Cu exhibited the highest concentrations, peaking during winter.