Long-term trends, health impacts, and economic costs of PM₂.₅ in Khorramabad, Iran (2014–2023)

BACKGROUND: Fine particulate matter (PM₂.₅) is one of the most harmful air pollutants, linked to serious health effects including cardiovascular and respiratory diseases, and premature mortality. Despite this, long-term data on PM₂.₅ exposure and its health impacts are limited in many regions of Iran. This study aimed to assess the long-term trends of PM₂.₅ concentration, estimate related health impacts, and evaluate economic costs in Khorramabad, a semi-arid city in western Iran, over a ten-year period (2014–2023). METHODS: PM₂.₅ data were collected from three air quality monitoring stations and analyzed for temporal trends using statistical and visualization tools. Health impacts, including all-cause, cardiovascular, COPD, and lung cancer mortality, were estimated using the WHO’s AirQ + model. The data were compared with WHO air quality guidelines to assess public health risks. For estimating the economic cost attributed to PM₂.₅, The human capital method (HCM) was used. RESULTS: PM₂.₅ concentrations showed significant seasonal and hourly variations, with the highest levels in summer months, particularly August. A decreasing trend in annual mean PM₂.₅ was observed after 2020, with the lowest average in 2023 (16.9 µg/m³). Health risk assessment revealed a declining trend in PM₂.₅-related premature deaths, from 662 in 2015 to 288 in 2023, with cardiovascular disease being the most affected outcome. The analysis revealed that over the ten-year study period, the economic burden estimation demonstrated an average annual cost of US$34.9 million (range: 19.1–43.9 million US dollars). CONCLUSION: Although air quality has improved in recent years, PM₂.₅ levels still often exceed WHO guidelines. Continued monitoring, stricter regulations, and regional cooperation are essential to reduce pollution and its health and economic cost burden.