Urban forests provide different ecosystem services, such as the removal of atmospheric pollutants, carbon sequestration, water and microclimate regulation, and habitat for wildlife. This improves environmental quality and the well-being of the population. In this study, the structure of the urban forest of the Aburrá Valley was analyzed and its contribution to the removal of atmospheric pollutants was estimated and valued using the i-Tree Eco software. For this purpose, 398 forest sampling plots were established and secondary information on climatic and pollution conditions was used. A 23% tree cover was found in the study area and a removal of 228 tons of pollutants per year (approximate value of 2.1 million USD). Finally, strategies are recommended for the optimization of this service and the creation of mechanisms to compensate for the loss of tree cover.

1. UN. World urbanization prospects: The 2014 revision. United Nations Department of Economics and Social Affairs, Population Division: New York, NY, USA; 2015. p. 41.

2. Comisión Económica para América Latina y el Caribe (Cepal). Población, territorio y desarrollo sos tenible. Santiago, Chile (Spanish) [Population, territory and sustainable development. Santiago, Chile]. 2012. Available from: https://repositorio.cepal.org/bitstream/handle/11362/22425/1/s2012034_es.pdf.

3. Departamento Nacional de Planeación (DNP). Conpes 3819: Política nacional para consolidar el sistema de ciudades en Colombia (Spanish) [Conpes 3819: National policy to consolidate the system of cities in Colombia]. 2014. Available from: https://colaboracion.dnp.gov.co/cdt/conpes/económicos/3819.pdf.

4. Grimm NB, Faeth SH, Golubiewski NE, et al. Global change and the ecology of cities. Science 2008; 319(5864): 756–760.

5. a)doi: 10.1126/science.1150195.

6. World Health Organization. Ambient (outdoor) air pollution. WHO; 2018. Available from: https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health.

7. Kampa M, Castanas E. Human health effects of air pollution. Environmental Pollution 2008; 151(2): 362–367. doi: 10.1016/j.envpol.2007.06.012.

8. Calderón-Garcidueñas L, Villarreal-Ríos R. Living close to heavy traffic roads, air pollution, and dementia. The Lancet 2017; 389(10070): 675–677. doi: 10.1016/s0140-6736(16)32596-x.

9. Prüss-Üstün A, Wolf J, Corvalán C, et al. Preventing disease through healthy environments: A global assessment of the burden of disease from environmental risks. World Health Organization; 2016. Available from: https://apps.who.int/iris/bitstream/handle/10665/204585/9789241565196_eng.pdf?sequence=1&isAllowed=y.

10. Cohen AJ, Anderson HR, Ostro B, et al. Urban air pollution. In: Ezzati E, Lopez AD, Rodgers A, and Murray CJL (editors). Comparative quantification of health risks: Global and regional burden of disease attributable to selected major risk factors. Geneva: World Health Organization; 2004. p. 1353–1433.

11. Instituto de Hidrología, Meteorología y Estudios Ambientales (IDEAM). Informe del estado de la calidad del aire en Colombia 2011-2015 (Spanish) [Report on the state of air quality in Colombia 2011-2015]. Bogotá; 2018. Available from: http://documentacion.ideam.gov.co/openbiblio/bvirtual/023637/informe_del_estado_de_la_calidad_del_aire_en_colombia_2011-2015_vfinal.pdf.

12. Gaviria CF, Benavides PC, Tangarife CA. Particulate air pollution (PM2. 5 and PM10) and medical consultations due to respiratory disease in Medellín (2008–2009). Revista Facultad Nacional de Salud Pública 2011; 29(3): 241–250.

13. Área metropolitana del Valle de Aburrá (AMVA). Desarrollo de una estrategia ambiental integrada para una movilidad sustentable en el área metropo litana del valle de Aburrá (Spanish) [Development of an integrated environmental strategy for sustainable mobility in the metropolitan area of Valle de Aburrá]. Medellín; 2015.

14. Área metropolitana del Valle de Aburrá (AMVA). Acuerdo Metropolitano n.° 15 (Spanish) [Metropolitan Agreement No.15]. 2016. Available from: http://www.metropol.gov.co.

15. SIATA. Información de calidad del aire (Spanish) [Air quality information]. Medellín: Sistema de Alerta Temprana de Medellín y el valle de Aburrá. 2018. Available from: https://siata.gov.co/descarga_siata/index.php/index2/calidad_aire/.

16. Baró F, Chaparro L, Gómez E, et al. Contribution of ecosystem services to air quality and climate change mitigation policies: The Case of urban forests in Barcelona, Spain. AMBIO 2014; 43: 466–479.

17. a)doi: 10.1007/s13280-014-0507-x.

18. Willis KJ, Petrokofsky G. The natural capital of city trees. Science 2017; 356(6336): 374–376. a)doi: 10.1126/science.aam9724.

19. Bodnaruk EW, Kroll CN, Yang Y, et al. Where to plant urban trees? A spatially explicit methodology to explore ecosystem service tradeoffs. Landscape and Urban Planning 2017; 157: 457–467. a)doi: 10.1016/j.landurbplan.2016.08.016.

20. Salbitano F, Borelli S, Conigliaro M, et al. Guidelines on urban and peri-urban forestry. FAO Forestry Paper; 2016, No.178. Available from: http: www.fao.org/3/a-i6210e.pdf.

21. Gómez-Baggethun E, Gren Å, Barton DN, et al. Urban ecosystem services. Urbanization,

22. a)biodiversity and ecosystem services: Challenges and opportunities. Springer, Dordrecht; 2013. p. 175–251. doi: 10.1007/978-94-007-7088-1_11.

23. Nowak DJ, Crane DE, Stevens JC. Air pollution removal by urban trees and shrubs in the United States. Urban Forestry & Urban Greening 2006; 4(3–4): 115–123. doi: 10.1016/j.ufug.2006.01.007.

24. Armson D, Rahman MA, Ennos AR. A comparison of the shading effectiveness of five different street tree species in Manchester, UK. Arboriculture & Urban Forestry 2013; 39(4): 157–164.

25. Reynolds CC, Escobedo FJ, Clerici N, et al. Does “greening” of neotropical cities considerably mitigate carbon dioxide emissions? The case of Medellin, Colombia. Sustainability 2017; 9(5): 785. doi: 10.3390/su9050785.

26. Dobbs C, Eleuterio AA, Amaya JD, et al. The benefits of urban and peri-urban forestry. Unasylva 2018; 69(250): 22–29.

27. Yang J, McBride J, Zhou J, et al. The urban forest in Beijing and its role in air pollution reduction. Urban Forestry & Urban Greening 2005; 3(2): 65–78. a)doi: 10.1016/j.ufug.2004.09.001.

28. Mcneil J, Vava C. Oakville’s urban forest: Our solution to our pollution. Canada: Town of Oakville; 2006.

29. Nowak DJ, Crane DE, Stevens JC, et al. A ground-based method of assessing urban forest structure and ecosystem services. Aboriculture & Urban Forestry 2008; 34(6): 347–358.

30. Rogers K, Sacre K, Goodenough J, et al. Valuing London’s urban forest: Results of the London i-Tree eco project. 2015. London: Treeconomics London. Available from: https://www.london.gov.uk/sites/default/files/valuing_londons_urban_forest_i-tree_report_final.pdf.

31. Ministerio de Ambiente y Desarrollo Sostenible (MADS). Resolución 2254 (Spanish) [Resolution 2254]. Bogotá: MADS; 2017. Available from: http: www.minambiente.gov.co/images/normativa/app/resoluciones/96-res2254de2017.pdf.

32. Escobedo FJ, Wagner JE, Nowak DJ, et al. Analyzing the cost effectiveness of Santiago, Chile’s policy of using urban forests to improve air quality. Journal of Environmental Management 2008; 86(1): 148–157. doi: 10.1016/j. jenvman.2006.11.029.

33. Horbath JE. Tendencias y proyecciones de la población del área metropolitana del valle de Aburrá en Colombia, 2010–2030 (Spanish) [Trends and projections of the population of the Aburrá Valley metropolitan area in Colombia, 2010–2030]. Notas de Población; 2016. Available from: https://www.cepal.org/es/publica-ciones/40259-tendencias-proyecciones-la-pobla-cion-area-metropolitana-valle-aburra-colombia.

34. Universidad Nacional de Colombia, Área Metropolitana del valle de Aburrá, Cornare y Corantioquia. Plan de ordenación y manejo de la cuenca del río Aburrá: aspectos principales (Spanish) [Planning and management plan for the Aburrá river basin: Main aspects]. Medellín: Impregon; 2007.

35. USDA Forest Service. I-Tree Eco User’s Manual V 5.0. 2013. Available from: www.itreetools.org.

36. Área metropolitana del Valle de Aburrá (AMVA). Actualización inventario de emisiones at mosféricas del valle de Aburrá (Spanish) [Updating inventory of atmospheric emissions from the Aburrá Valley]. 2017. Available from: http://www.metropol.gov.co.

37. Nowak DJ. Institutionalizing urban forestry as a “biotechnology” to improve environmental quality. Urban Forestry & Urban Greening 2006; 5(2): 93–100. doi: 10.1016/j.ufug.2006.04.002.

38. Yang J, Chang Y, Yan P. Ranking the suitability of common urban tree species for controlling PM 2.5 pollution. Atmospheric Pollution Research 2015; 6(2): 267–277. doi: 10.5094/apr.2015.031.

39. Setälä H, Viippola V, Rantalainen AL, et al. Does urban vegetation mitigate air pollution in northern conditions? Environmental Pollution 2013; 183: 104–112. doi: 10.1016/j.envpol.2012.11.010.

40. Área metropolitana del Valle de Aburrá (AMVA). Plan integral de gestión de contaminación del aire (Spanish) [Comprehensive air pollution management plan]. 2017. Available from: http://www.calidaddelaire.co/pigeca.php.

41. Grote R, Samson R, Alonso R, et al. Functional traits of urban trees: air pollution mitigation potential. Frontiers in Ecology and the Environment 2016; 14(10): 543–550. doi: 10.1002/fee.1426.

42. Nowak DJ. I-Tree species selector user’s manual. Syracuse, Nueva York: Usda Forest Service; 2008. Available from: https://www. itreetools.org/resources/manuals/i-treespeciesusersmanual.

43.

44. Weerakkody U, Dover JW, Mitchell P, et al. Evaluating the impact of individual leaf traits on atmospheric particulate matter accumulation using natural and synthetic leaves. Urban Forestry & Urban Greening 2018; 30: 98–107. doi: 10.1016/j.ufug.2018.01.001.

45. Prajapati SK, Tripathi BD. Anticipated Performance Index of some tree species considered for green belt development in and around an urban area: A case study of Varanasi city, India. Journal of Environmental Management 2008; 88(4): 1343–1349. doi: 10.1016/j.jenvman.2007.07.002.

46. Zhang P, Liu Y, Chen X, et al. Pollution resistance assessment of existing landscape plants on Beijing streets based on air pollution tolerance index method. Ecotoxicology and Environmental Safety 2016; 132: 212–223. doi: 10.1016/j.ecoenv.2016.06.003.

47. Janhäll S. Review on urban vegetation and particle air pollution—Deposition and dispersion. Atmospheric Environment 2015; 105: 130–137. a)doi: 10.1016/j.atmosenv.2015.01.052.

48. Vos PEJ, Maiheu B, Vankerkom J, et al. Improving local air quality in cities: to tree or not to tree? Environmental Pollution 2013; 183: 113–122. a)doi: 10.1016/j.envpol.2012.10.021.

49. Maher BA, Ahmed IAM, Davison B, et al. Impact of roadside tree lines on indoor concentrations of traffic-derived particulate matter. Environmental Science & Technology 2013; 47(23): 13737–13744. doi: 10.1021/en404363m.

50. Área metropolitana del Valle de Aburrá (AMVA). Acuerdo Metropolitano n.° 19 (Spanish) [Metropolitan agreement No.19]. 2017. Available from: http://www.metropol.gov.co.

51. BancO2. BancO2 Servicios Ambientales Comuni tarios (Spanish) [BancO2 community environmental services]. 2018. Available from: http://www.banco2.com/.