Usefulness of Tree Species as Urban Health Indicators.

We used the Air Pollution Tolerance Index (APTI), the amount of PM and PM, and the elemental analysis of leaves to explore the sensitivity of tree species to air pollution. We assessed the tolerance of , , × , , , , , and × to the amount of dust, APTI, and the elemental concentration of leaves. Leaves were collected in Debrecen (Hungary), which has a high intensity of vehicular traffic. The highest amount of PM (both PM and PM) was found on the leaves of . and . . Our results demonstrated that . was moderately tolerant, while . was intermediate, based on the APTI value. There was a significant difference in the parameters of APTI and the elemental concentration of leaves among species. We found that tree leaves are reliable bioindicators of air pollution in urban areas. Based on the value of APTI, . and . , and based on PM, . and . are recommended as pollutant-accumulator species, while other studied species with lower APTI values are useful bioindicators of air pollution. The results support landscape engineers and urban developers in finding the best tree species that are tolerant to pollution and in using those as proxies of urban environmental health.