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4 Contribution of the various sources of particulate matter (PM 10 and PM 2.5 ) to the air quality of the Metropolitan Region. (Source: USACH 2014))
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Most Latin American cities have air quality problems owing to high levels of particulate matter and ozone. By 2050, it is expected that more than 80% of Latin Americans will live in urban areas, leading to an increment in pollution problems. Santiago, Chile shows a high level of pollution from PM10 and PM2.5, especially during the autumn–winter per...
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... Further data show that primary emissions of NOx and VOCs from motor vehicle exhausts continue to be the main driver of photochemical air pollution in the MR [45]. However, urban vegetation also emits biogenic volatile organic compounds (BVOCs), which are highly reactive and contribute to O 3 formation due to their ecophysiological functions [2,10,46]. BVOCs include alkanes, alkenes, carbonyls, alcohols, esters, ethers, and acids [47], of which terpenes are the most important. The basic molecule of terpenes is isoprene (2-methyl-1,3-butadiene, C 5 H 8 ), a highly reactive compound due to its double bonds. ...
... Rising private vehicle use and emissions of NOx and VOC are the most important factors producing photochemical pollution, with evidence showing a VOC-limited ozone formation regime [44,45]. Harmful ozone days remained high in the east and northeast areas of the MR [10,45]. ...
Tropospheric ozone (O3) and other pollutants significantly affect Chile’s Metropolitan Region, posing risks to human health. As a secondary pollutant and a major photochemical oxidant, O3 formation is driven by anthropogenic volatile organic compounds (AVOCs) from the residential and transport sectors, the main sources of gaseous emissions. This study evaluated the AVOC capture capacity of leaf material from two tree species, Quillaja saponaria (native species) and Robinia pseudoacacia (exotic species), as potential urban biomonitors. Leaf samples were collected near nine SINCA official monitoring stations and the Antumapu University Campus, stored frozen, and analyzed by HS-SPME-GC/MSD for AVOC quantification. Photochemical reactivity and O3 formation potential were assessed using equivalent propylene concentration (Prop-Equiv) and Ozone Formation Potential (OFP) methods. The results showed that both species captured atmospheric AVOCs, confirming their role as bioindicators. However, Q. saponaria adsorbed significantly higher AVOC concentrations and exhibited greater tropospheric O3 formation potential than R. pseudoacacia. Given the AVOC adsorption capacity of both tree species, they could be used as biomonitors for styrene and also as a biomonitor for toluene in the case of Q. saponaria. This research highlights the importance of selecting tree capacity to improve urban air quality.
... In this sense, fine particulate matter is identified among criterion-type air pollutants, with diameters of 1.0 to 2.5 µm (µm), known as PM 2.5 [4]. This pollutant is estimated to come from 20% of fixed sources, while the remaining 80% is contributed by mobile sources [5]. In previous studies, vehicle exhaust represents an important anthropogenic source of fine airborne particles in urban areas [6]. ...
... On the other hand, 11 of the 15 sampling sites are near vegetated areas, including some densely vegetated covers such as San Cristóbal and Blanco hills (located E and NE from the sampling sites) and Los Reyes and Forestal parks (located S and SW from the sampling sites) (Fig. 1). Vegetation contributes to improve air quality due to the capture of PM and the absorption of gases (Escobedo et al., 2011;Gao et al., 2015;Nowak et al., 2013;Préndez et al., 2019). On the > PM10 fraction, a peak was observed at SE2 which coincides with the pollen size range (Ramli et al., 2020). ...
Santiago, capital city of Chile, presents air pollution problems for decades mainly by particulate matter, which significantly affects population health, despite national authority efforts to improve air quality. Different properties of the particulate matter (PM10, PM2.5 and PM1 fractions, particle surface and number) were measured with an optical spectrometer. The sampling was done during spring 2019 at different sites within the official representative area of Independencia monitoring station (ORMS-IS). The results of this study evidence large variations in PM mass concentration at small-scale areas within the ORMS-IS representative zone, which reports the same value for the total area. Results from PM properties such as PM1, particle number and particle surface distribution show that these properties should be incorporated in regular monitoring in order to improve the understanding of the effects of these factors on human health. The use of urban-climate canopy-layer models in a portion of the sampled area around the monitoring station demonstrates the influence of street geometry, building densities and vegetation covers on wind velocity and direction. These factors, consequently, have an effect on the potential for air pollutants concentrations. The results of this study evidence the existence of hot spots of PM pollution within the area of representativeness of the ORMS-IS. This result is relevant from the point of view of human health and contributes to improve the effectiveness of emission reduction policies.
... Tropospheric ozone moving inside the leaf through the stomata brings about the production of reactive oxygen species damaging the photosynthetic machinery [7] despite the plant's increased production of compounds with antioxidative capacity [8]. The city of Santiago, Chile, exhibits serious problems with O 3 during the spring-summer period [9][10][11]. The threshold for ozone is 120 µg m −3 , considering an 8 h mobile average, being frequently exceeded during springsummer, especially in the northeast of the city [10]. ...
... The city of Santiago, Chile, exhibits serious problems with O 3 during the spring-summer period [9][10][11]. The threshold for ozone is 120 µg m −3 , considering an 8 h mobile average, being frequently exceeded during springsummer, especially in the northeast of the city [10]. A recent work monitoring ozone concentration in eastern Santiago during the period 2010-2018 showed that on average 43 days per year were above the recommended levels and that the ozone formation regime is VOC-limited [12]. ...
This study assessed leaf fluxes of CO2, CH4 and biogenic volatile organic compounds (BVOC) for two common urban tree species, Platanus × acerifolia (exotic) and Schinus molle (native), widely distributed in Santiago, Chile. The emission factors (EF) and the Photochemical Ozone Creation Index (POCI) for S. molle and P. × acerifolia were estimated. The global EF was 6.4 times higher for P. × acerifolia compared with S. molle, with similar rates of photosynthesis for both species. Isoprene represented more than 86% of the total BVOCs leaf fluxes being 7.6 times greater for P. × acerifolia than S. molle. For P. × acerifolia, BVOCs represented 2% of total carbon fixation while representing 0.24% for S. molle. These results may suggest that plant species growing outside their ecological range may exhibit greater BVOCs leaf fluxes, proportional to photosynthesis, compared to well-adapted ones. The results found may contribute to better urban forest planning.
... Cambios superiores a 60° en la dirección del viento predominante del sur (193°) y su relación espacial con los edificios (en negro) en la comuna de Estación Central Fuente: Elaboración propia Para la totalidad de los problemas ambientales mencionados, la forestación se convierte en un elemento esencial para el mejoramiento de los climas urbanos: consume calor en el proceso de evapotranspiración y proporciona sombra (que en el caso de Santiago es una forma muy relevante de mitigar los efectos de la temperatura) y humidifica la atmósfera, controlando los valores extremos; ayuda a la adsorción de contaminantes en sus hojas y troncos (Burden, 2006) y recicla contaminantes como el CO 2 transformándolo en oxígeno. En el caso de la vegetación nativa, estas transformaciones son únicas en comparación con los árboles exóticos que producen contaminantes (Préndez et al., 2019); oferta refugios a la biodiversidad y brinda confortabilidad climática y espacios de alta valoración para el bienestar y salud humana. ...
... Algunas especies recomendadas para el arbolado urbano son peumos (Cryptocaria alba), quillayes (Quillaja saponaria) y canelos (Drimys winteri), especies perennes (siempre verdes), nativas de Chile, que tienen hojas relativamente pequeñas y son resistentes a la escasez de agua, haciendo que sus superficies sean más rígidas. Estas características son interesantes en la medida que son funcionales ante los cambios estacionales: en verano, proporcionan sombra, mientras que en invierno pueden ayudar en la purificación del aire, adhiriendo contaminantes dispersos en el aire en sus superficies foliares (Préndez et al., 2019). Sin embargo, se deben evitar los monocultivos, porque pueden comprometer la diversidad genética, dejando el arbolado urbano susceptible a las plagas, como la enfermedad del olmo holandés, que ocurrió por accidente en el este de los Estados Unidos a mediados del siglo XX, devastando millones de árboles (Sadava et al., 2009). ...
Despite available models and scientific evidence on climate change on a global scale, the planning and management of urban territories in Latin America has failed to consider it above its economic, social and political constraints. By selecting surface temperature and ventilation as critical climate variables, the case of Santiago de Chile is analyzed as an example of the contradictions between policies and official declarations and the real transformations of urban climates, highlighting the widespread increase in surface temperatures, represented by satellite imagery, due to the absence of rigorous environmental assessments of changes in land uses and covers that have accompanied the urbanization. A microclimatic simulation has allowed estimating the reduction of speed and changes in the direction of the winds, such as consequence of the densification and verticalization in the Estación Central commune. The generation of ventilation "dead zones" relates to designs, topology and exposure of the buildings, affecting the quality of life of the inhabitants. Mitigation and adaptation to Climate Change should be an explicit part of the objectives, plans and projects that pursue the quality and territorial justice of urban climates and, consequently, the well-being and comfort of society.
... In Fig. 2c, the concentration of OC emission rate is very high (7.23 × 10 −4 Tg/year to 1.25 × 10 −3 Tg/year) on Gujranwala, Faisalabad, Lahore, Multan, Dera Ghazi Khan, Bahawalpur, Karachi, Mardan, Peshawar, Bannu, Srinagar, Kashmir, Rajauri, Jammu, and Larkana because of emissions rate from industrial, transport, waste, residential wood fumes, and agricultural waste sources. Beside this, the intense solar rays and elevated temperature catalyze the chemical in a higher rate of diffusion, which in turns results in the release of biogenic volatile compounds from plants, into the atmosphere, which sometimes further leads to the formation of the inversion layer in winter, thus causing high accumulation of OC in the atmosphere (Durand et al. 2007;Préndez et al. 2019;Toro Araya et al. 2014). Over the regions of Hyderabad, Mirpur, Ram of Kutch, F.A.T.A., Kohat, Doda, and Mirpur Khas, the OC concentration is ranging from 4.87 × 10 −4 to 2.85 × 10 −4 Tg/year. ...
Organic carbon (OC) is the amount of carbon found in an organic compound. Once entered, the environment OC may cause climate change and effects on public health. The objective of the study was to assess the spatio-temporal trends of OC, climatology, and to develop inventories. The three satellite datasets (MACCity, ACCMIP, RCP 8.5) showed significant different trends in OC levels. Results indicated significantly higher trends in OC distribution during anthropogenic activities and the industrial era as compared with natural sources and the pre-industrial era. The residential and industrial sectors showed higher emission of OC 1.0 × 10−5to 2.5 × 102 Tg/year, respectively as compared with other sectors. Spatial distribution of OC revealed higher levels in bigger cities (Islamabad, Lahore, Karachi, Multan, Punch, and Mardan districts) of Pakistan. The temporal analysis shows irregular increasing trends in OC distribution with the passage of time. Principal component analysis (PCA) revealed that residential OC showed a positive correlation with surface temperature, wind and heat and OC transport, sum, residential, and energy sector with relative humidity in MACCity and RCP 8.5 datasets, respectively. The study indicated that savanna burning and residential sectors were a major contributor to the level of OC. The results will be helpful for the government to devise policies regarding OC management.
... On average, Santiago more than doubles the mean concentrations above the annual WHO recommendations (WHO, 2016), for both PM10 and PM2.5, especially during the autumn-winter period. Moreover, the Chilean normative for ozone (O 3 ) is exceeded several days in the eastern part of the city during the spring-summer season (Préndez et al., 2019). ...
... To estimate the emissions from biogenic sources, the MEGAN2.1 program was used, including the latest improvements implemented in 2012 by the National Center for Atmospheric Research (Guenther et al., 2012). Préndez et al. (2019) experimentally quantified emissions of BVOCs from different urban tree species in Santiago, which corresponded mainly to terpenes (isoprene and monoterpenes). ...
Anthropogenic volatile organic compounds (AVOCs) represent the third largest contribution in gaseous emissions in the urban and peri-urban region of Santiago, the capital of Chile. Some of these compounds are toxic or mutagenic, cause serious damage to human health, and decrease plant growth and development. There is little international information related to atmospheric AVOCs in leaf content from trees exposed to specific sources of pollution, and to our knowledge, there is no research on this topic in Chile. The purpose of this work was to study the leaf content of AVOCs from the Organic Range of Gasoline (ORG: range 6–10 C) emitted by local traffic during the austral summer and spring seasons in leaves of two exotic tree species (Liriodendron tulipifera and Platanus × acerifolia). Leaf samples collected around 2 meters height above the ground were pulverized with a cryogenic mill and eleven chemical components were quantified (toluene, 1,2,4-trimethylbenzene (1,2,4-TMB), styrene, ethylbenzene, ortho, meta and para-xylenes, naphthalene, 1,3,5-trimethylbenzene (1,3,5-TMB), isopropylbenzene, and trichloroethene) using GC-MSD MSD. Benzene was detected but not quantified, because it was always under the quantification limit of the technique. Differences in concentrations were found for type of site exposure, season and tree species. The differences found in leaf content of AVOCs in P. × acerifolia exposed to vehicle traffic suggest that the concentration of these contaminants in leaves may be due to AVOC capturing. Considering the content of AVOCs in leaves and not in the whole individual tree, L. tulipifera presented a higher concentration of total AVOCs than P. × acerifolia for both seasons. The Prop-Equiv and OFP of L. tulipifera were very high in summer, being 13.6 and 14.8 times greater, respectively, than the corresponding values for P. × acerifolia.
The city of Kirkuk is facing a real crisis in increasing air pollution due to the oil facilities and the lack of trees and their uneven distribution, which exacerbated the problem. This study aims to demonstrate the effect (size, type, and distribution) of urban trees on air pollution in Kirkuk, with a focus on simulating the dispersion of pollutants resulting from the oil refinery. using the Gaussian dispersion model. We will assess the role of existing trees in reducing pollution and explore the potential benefits of planting new trees and their role in reducing air pollution. The study's results inform urban tree’s role in reducing air pollution and strategies for integrating them into city planning. The Gaussian model adds scientific rigor, accurately simulating and evaluating pollution distribution. This methodology serves as a strong basis for analyzing tree effects on air pollution in Kirkuk and other urban areas, aiding evidence-based decision-making to improve air quality and public health.
The state of peoples’ physiology, mental health and well-being are affected when people actively use the forest or urban greenspaces. Studies have been conducted to prove that trees and forests are beneficial for reducing stress, decreasing depression, fighting against obesity and improving physical health. With the continuous usage of forest and urban greenspaces, from a small scale escalating to a big one, passive or active, all will gain the benefits. Accessibility, motivation and a good sense of time consumption to use the forest and urban greenspace wisely is also a chance for people to enhance their immune functions, increase physical activity and social connectedness. Many studies have used a few types of questionnaires, to see the effect of greening areas on human health. Apart from that, applied science measurements are also used in some studies to gain further scientific evidence. Results indicate that people living near and surrounding green spaces showed more health, energy, and happiness. Thus, results also show urban greening has positive benefits physiologically and psychologically compared to the urban environment.
