Assessment of air pollution removal by urban trees based on the i-Tree Eco Model: The case of Tehran, Iran

Abstract As the population grows and economic development accelerates, urbanization is also increasing at a fast pace and this has resulted in severe air pollution that poses a significant threat to human health. Air quality issues have become increasingly serious in metropolises like Tehran (Iran) in recent years. Hence, this study aims to estimate the role of Tehran’s urban trees in air pollution removal and evaluate this ecosystem service’s economic value, based on the i-Tree Eco model. This study’s results illustrate that Tehran urban trees produce 160,271.4 tons of oxygen and remove 1286.42 tons of pollutants in 2020. The rate of air pollution removal varies among pollutants which are 134.83, 299.68, 270.32, 0.68, 489.41, and 91.50 t yr− 1 for the CO, NO2, O3, PM2.5, PM10, and SO2, respectively, with an associated monetary value of US$ 1,536,619. This effect is small compared to the amount of pollution emitted in 2020 (0.17%) due to the high emissions rate and low per capita green space in Tehran. Therefore, tree planting should not be considered a single solution to emission reduction but rather a complementary one. The findings could serve as a basis for future replication in other locations and serve as a guide for enhancing urban green spaces to promote sustainable urban development.