Browsing by Subject "air pollution"

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  • Clifton, O.E.; Paulot, F.; Fiore, A.M.; Horowitz, L.W.; Correa, G.; Baublitz, C.B.; Fares, S.; Goded, I.; Goldstein, A.H.; Gruening, C.; Hogg, A.J.; Loubet, B.; Mammarella, I.; Munger, J.W.; Neil, L.; Stella, P.; Uddling, J.; Vesala, T.; Weng, E. (2020)
    Identifying the contributions of chemistry and transport to observed ozone pollution using regional-to-global models relies on accurate representation of ozone dry deposition. We use a recently developed configuration of the NOAA GFDL chemistry-climate model - in which the atmosphere and land are coupled through dry deposition-to investigate the influence of ozone dry deposition on ozone pollution over northern midlatitudes. In our model, deposition pathways are tied to dynamic terrestrial processes, such as photosynthesis and water cycling through the canopy and soil. Small increases in winter deposition due to more process-based representation of snow and deposition to surfaces reduce hemispheric-scale ozone throughout the lower troposphere by 5-12 ppb, improving agreement with observations relative to a simulation with the standard configuration for ozone dry deposition. Declining snow cover by the end of the 21st-century tempers the previously identified influence of rising methane on winter ozone. Dynamic dry deposition changes summer surface ozone by -4 to +7 ppb. While previous studies emphasize the importance of uptake by plant stomata, new diagnostic tracking of depositional pathways reveals a widespread impact of nonstomatal deposition on ozone pollution. Daily variability in both stomatal and nonstomatal deposition contribute to daily variability in ozone pollution. Twenty-first century changes in summer deposition result from a balance among changes in individual pathways, reflecting differing responses to both high carbon dioxide (through plant physiology versus biomass accumulation) and water availability. Our findings highlight a need for constraints on the processes driving ozone dry deposition to test representation in regional-to-global models.
  • Havas, Paavo (Suomen metsätieteellinen seura, 1971)
  • Eriksson, J.; Bergholm, J.; Kvist, K. (Suomen metsätieteellinen seura, 1981)
  • Martikainen, Maria-Viola; Rönkkö, Teemu J.; Schaub, Bianca; Täubel, Martin; Gu, Cheng; Wong, Gary W. K.; Li, Jing; Pekkanen, Juha; Komppula, Mika; Hirvonen, Maija-Riitta; Jalava, Pasi I.; Roponen, Marjut (2018)
    Background Studies conducted in farm environments suggest that diverse microbial exposure promotes children's lung health. The underlying mechanisms are unclear, and the development of asthma-preventive strategies has been delayed. More comprehensive investigation of the environment-induced immunoregulation is required for better understanding of asthma pathogenesis and prevention. Exposure to air pollution, including particulate matter (PM), is a risk factor for asthma, thus providing an excellent counterpoint for the farm-effect research. Lack of comparable data, however, complicates interpretation of the existing information. We aimed to explore the immunoregulatory effects of cattle farm dust (protective, Finland) and urban air PM (high-risk, China) for the first time using identical research methods. Methods We stimulated PBMCs of 4-year-old children (N = 18) with farm dust and size-segregated PM and assessed the expression of immune receptors CD80 and ILT4 on dendritic cells and monocytes as well as cytokine production of PBMCs. Environmental samples were analysed for their composition. Results Farm dust increased the percentage of cells expressing CD80 and the cytokine production of children's immune cells, whereas PM inhibited the expression of important receptors and the production of soluble mediators. Although PM samples induced parallel immune reactions, the size-fraction determined the strength of the effects. Conclusions Our study demonstrates the significance of using the same research framework when disentangling shared and distinctive immune pathways operating in different environments. Observed stimulatory effects of farm dust and inhibitory effects of PM could shape responses towards respiratory pathogens and allergens, and partly explain differences in asthma prevalence between studied environments.
  • Heliövaara, Kari; Väisänen, Rauno (Suomen metsätieteellinen seura, 1988)
  • Heliövaara, Kari; Väisänen, Rauno (Suomen metsätieteellinen seura, 1989)
  • Liu, Xin (2021)
    This article concerns the relation between health, the embodied self-tracking subject and the environment in postsocialist China. Instead of simply expanding the framework of neoliberal subject to the question of health and the phenomenon of tracking and sharing data of “smog jog” in the Chinese context, this article addresses the following two inter-related questions: (1) how might an investigation of the practices of self-tracking “smog jog” in the context of postsocialist China afford a reconsideration of health; (2) how might an examination of the ways in which health is interpreted, performed and negotiated through practices of monitoring, measuring and recording a jog and the air quality in postsocialist China rework the conception of self-tracking. This article examines posts on Sina Weibo, which is one of the most popular social media platforms in China, in which Weibo users record and describe their jog in the smog. It argues that the configuration and performance of health and the embodied self-tracking subjects are multiple, and are informed by, negotiated with and find expressions in the environment in postsocialist China.
  • Westman, Lars (Suomen metsätieteellinen seura, 1981)
  • Raunemaa, T.; Hautojärvi, A.; Katainen, H.-S.; Erkinjuntti, R.; Gerlander, M.; Kaisla, K. (Suomen metsätieteellinen seura, 1981)
  • Pakonen, Tuulikki (Suomen metsätieteellinen seura, 1981)
  • Heliövaara, Kari; Väisänen, Rauno (Suomen metsätieteellinen seura, 1986)
  • Heliövaara, Kari; Väisänen, Rauno (Suomen metsätieteellinen seura, 1989)
  • Vestenius, Mika (Ilmatieteen laitos - Finnish Meteorological Institute, 2021)
    Finnish Meteorological Institute Contributions 178
    Air pollution is an important environmental risk to human health and ecosystems around the world. Particulate matter (PM), especially fine particulate matter, is an important part of this air pollution problem. Particle composition varies greatly and depends on the emission source. In addition to inorganic components, organic particulate fraction can contain several hundred organic compounds from anthropogenic and natural sources. The health risk of particulate is related to the particle size and the compounds inside or on the surface of the aerosol particles. The overall aim of this thesis was to study the selected chemical substances of atmospheric aerosol from both anthropogenic and natural sources. Concentrations of polycyclic aromatic hydrocarbons (PAH) and biogenic organic acids in aerosol were measured, and their effect on the local air quality was estimated. The sources of PAHs, trace elements, biogenic volatile organic compounds (BVOCs), and persistent organic compounds (POPs) in air were studied using positive matrix factorization (PMF), which was used as the main source apportionment tool in three of five papers and for the unpublished data in this thesis. Particles from burning emissions, e.g., diesel particles and particles from biomass burning, are the most toxic in our daily environment. Because of intensive wood use for heating and in sauna stoves, residential biomass burning is the major PAH air pollution source in Finland. Sources of atmospheric PAH pollution and its influence on local air quality were estimated at Virolahti background air quality station and in the Helsinki Metropolitan Area (HMA). The main source of PAHs at Virolahti were found to be combustion- and traffic-related source from the direction of St. Petersburg. Instead, local traffic appeared to have a very small influence on PAH levels in HMA, as local residential wood burning was found to be the main b(a)p source in Helsinki Metropolitan Area. Biogenic VOCs like monoterpenes and sesquiterpenes are highly reactive and oxidize rapidly in the atmosphere, producing secondary organic aerosol (SOA). We showed that positive matrix factorization (PMF) is a useful tool in estimating separate sources in a quasistationary dynamic system like ambient VOC concentrations in the boreal forest. Selected biogenic organic acids were measured from fine particles in the boreal forest in order to estimate their influence on aerosol production. Results indicated that sesquiterpene emissions from boreal forest are probably underestimated and their oxidation products probably have more important role in the SOA production that previously estimated. The Kola Peninsula area was found to be the major source of heavy metal pollution at Pallas. However, as Norilsk Nickel has now partly shut down its metallurgical operations, the trace element and SO2 emissions from the Kola Peninsula should be declining in the future. The ambient concentrations of POP compounds are globally declining but, in the Arctic, for some compounds this is not the case. In the source apportionment study for Pallas 1996–2018 POPs data, relatively big portion of measured POPs at Pallas came within the marine source from clean areas from the north. These long-lived compounds, which have migrated into the Arctic from the southern areas along the air and sea currents for many decades, are now released back into the atmosphere from the melting Arctic ice cover due to global warming. For these compounds, the Arctic has turned from the sink to the source.
  • Hautojärvi, A.; Raunemaa, T.; Lappalainen, T.; Ahonen, S.; Katainen, H.-S.; Erkinjuntti, R. (Suomen metsätieteellinen seura, 1981)
  • Huttunen, Satu; Karhu, Marketta; Kallio, Sinikka (Suomen metsätieteellinen seura, 1981)
  • Karttunen, Sasu (Helsingin yliopisto, 2020)
    Air pollution is the most severe environmental problem in the world in terms of human health. The World Health Organisation (WHO) estimates that 91% of the world's population is exposed to high air pollutant levels. The risks are particularly high in urban areas, where often high population densities are combined with high air pollutant levels. Urban street canyons are especially prone to high pollutant levels due to the proximity of traffic and reduced exchange of air with the street canyon and air above, referred to as ventilation. As a result, one of the most important topics in city planning is how to avoid designs that impact the air quality negatively. Street trees are often planted in street canyons for aesthetic purposes while they can also improve thermal comfort. The air quality within street canyons is affected by street trees in two ways. They provide leaf surface for air pollutants to deposit on, thus cleaning the air. On the other hand, they block the airflow within the street canyon, thus decreasing the ventilation of air pollutants. In previous studies the latter effect has generally been found stronger. However, due to the various benefits of street trees, leaving them completely out from street canyon designs is rarely an option. The City of Helsinki is planning to develop its current inbound motorways into city boulevards which has raised concerns towards the local air quality levels due to high projected traffic rates. The aim of this study was to find which of five street-tree scenarios, realistic for the city boulevards, is the best in terms of air quality. Pedestrian-level aerosol mass concentrations were used as the measure of air quality. Furthermore the impacts of vegetation and dependency of aerosol mass concentrations on various flow statistics were studied in order to explain the differences between the scenarios. Large-eddy simulation (LES) model PALM was utilised to study the flow field above and within a city boulevard and to model the dispersion of traffic-related aerosols. Aerosol particles of different sizes were represented using a sectional aerosol model SALSA. The suitability of the used LES setup for such intercomparison studies was also investigated. The results showed that the street trees have generally a considerable negative impact (-2% to 54%) on pedestrian-level aerosol mass concentrations. Trees were find to reduce the mean wind speeds within the street canyon, which correlated strongly with the pedestrian-level concentrations. This was particular with a parallel wind direction to the street canyon due to decreased ventilation. Turbulence produced by the street trees was partially able to compensate for the reduced ventilation in some scenarios. The increased turbulence could be observed up to heights exceeding the maximum building height. Based on the results, it is recommended to prefer variable-height street-tree canopies over uniform ones within street canyons similar to the studied one. Uneven canopy increases turbulence and related pollutant transport which partially compensates decreased ventilation due to decreased wind speeds. It is also recommendable to consider minimising the ratio of the total crown volume to the street canyon volume, as ventilation decreases sharply as the ratio increases.