Browsing by Subject "air quality"

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  • Petäjä, Tuukka; Ovaska, Aino; Fung, Pak Lun; Poutanen, Pyry; Yli-Ojanperä, Jaakko; Suikkola, Jari; Laakso, Mikko; Mäkelä, Taneli; Niemi, Jarkko V.; Keskinen, Jorma; Järvinen, Anssi; Kuula, Joel; Kurppa, Mona; Hussein, Tareq; Tarkoma, Sasu; Kulmala, Markku; Karppinen, Ari; Manninen, Hanna E.; Timonen, Hilkka (2021)
    Poor air quality influences the quality of life in the urban environment. The regulatory observation stations provide the backbone for the city administration to monitor urban air quality. Recently a suite of cost-effective air quality sensors has emerged to provide novel insights into the spatio-temporal variability of aerosol particles and trace gases. Particularly in low concentrations these sensors might suffer from issues related e.g., to high detection limits, concentration drifts and interdependency between the observed trace gases and environmental parameters. In this study we characterize the optical particle detector used in AQT530 (Vaisala Ltd.) air quality sensor in the laboratory. We perform a measurement campaign with a network of AQT530 sensors in Helsinki, Finland in 2020-2021 and present a long-term performance evaluation of five sensors for particulate (PM10, PM2.5) and gaseous (NO2, NO, CO, O-3) components during a half-year co-location study with reference instruments at an urban traffic site. Furthermore, short-term (3-5 weeks) co-location tests were performed for 25 sensors to provide sensor-specific correction equations for the fine-tuning of selected pollutants in the sensor network. We showcase the added value of the verified network of 25 sensor units to address the spatial variability of trace gases and aerosol mass concentrations in an urban environment. The analysis assesses road and harbor traffic monitoring, local construction dust monitoring, aerosol concentrations from fireworks, impact of sub-urban small scale wood combustion and detection of long-range transport episodes on a city scale. Our analysis illustrates that the calibrated network of Vaisala AQT530 air quality sensors provide new insights into the spatio-temporal variability of air pollution within the city. This information is beneficial to, for example, optimization of road dust and construction dust emission control as well as provides data to tackle air quality problems arising from traffic exhaust and localized wood combustion emissions in the residential areas.
  • Heiskanen, Ilmari (Helsingin yliopisto, 2021)
    Interest towards indoor air quality has increased for several decades from human health perspective. In order to evaluate the quality of indoor air in terms of volatile organic compound (VOC) levels, robust analytical procedures and techniques must be used for indoor air VOC measurements. Since indoor building materials are the greatest source of indoor VOC emissions, same kind of procedures must be used for analysis of emission rates from building materials and their surfaces. Theory part of this thesis reviews background of VOCs and human health, legislation and guideline values, common building materials with emissions and used sampling techniques/approaches for indoor air sampling and surface material emission rate sampling & analysis. Discussed sampling techniques include, for example, material emission test chambers, field and laboratory test emission cells, solid phase microextraction (SPME) fibre applications and Radiello passive samplers. Also new innovative approaches are discussed. Used common analysis instruments are Gas Chromatography (GC) with Mass Spectrometer (MS) or Flame Ionization Detector (FID) for VOCs and High-Performance Liquid Chromatography-Ultraviolet/Visible light detector (HPLC-UV/VIS) for carbonyl VOCs (e.g. formaldehyde) after suitable derivatization. Analytical procedures remain highly ISO 16000 standard series orientated even in recent studies. In addition, potential usage of new modern miniaturized sample collection devices SPME Arrow and In-tube extraction (ITEX) used in experimental part of this thesis are discussed as an addition to indoor air and VOC emission studies. The aim of the experimental part of this thesis was to develop calibrations for selected organic nitrogen compounds with SPME Arrow and ITEX sampling techniques and test the calibration with indoor and outdoor samples. A calibration was successfully carried out with SPME Arrow (MCM-41 sorbent), ITEX (MCM-TP sorbent) and ITEX (Polyacrylonitrile (PAN) 10 % sorbent) with permeation system combined with GC-MS for the following selected organic nitrogen compounds: triethylamine, pyridine, isobutyl amine, allylamine, trimethylamine, ethylenediamine, dipropyl amine, hexylamine, 1,3-diaminopropane, 1-methyl-imidazole, N, N-dimethylformamide, 1,2-diaminocyclohexane, 1-nitropropane and formamide. The overall quality of the calibration curves was evaluated, and the calibrations were compared in terms of linear range, relative standard deviation (RSD) % for accepted calibration levels and obtained Limits of Detection (LOD) values. Also, ways to improve the calibrations were discussed. The calibration curves were tested with real indoor and outdoor samples and quantitative, as well as semi-quantitative, results were obtained.
  • Rubio-Iglesias, José Miguel; Edovald, Triin; Grew, Robert; Kark, Timo; Kideys, Ahmet Erkan; Peltola, Taru; Volten, Hester (Frontiers Media S.A., 2020)
    Frontiers in climate 2 (2020), 600998
    Environmental Protection Agencies (EPAs) have been involved in citizen science initiatives for decades, engaging with citizens with the goal of protecting and restoring our environment. Yet the data and knowledge generated and the possibilities for engaging citizens have grown significantly in the last decades thanks to the recent developments in mobile technologies and the access to internet, resulting in a transformation of how environmental protection can be done. This perspective provides some examples on how European EPAs and their partners are currently addressing key environmental challenges and exploring new institutional approaches by bringing in citizen science data and methods. It also points out challenges that need to be addressed to fully realize the potential of citizen science as a complement to the monitoring efforts by these agencies. Finally, it presents the Interest Group on Citizen Science of the Network of the Heads of Environmental Protection Agencies (EPA Network), an informal forum where EPAs across Europe share examples and bring together strategic insights on citizen science approaches into their daily activities.
  • Vira, Julius (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 130
    Atmospheric chemistry and transport models are used for a wide range of applications which include predicting dispersion of a hazardous pollutants, forecasting regional air quality, and modelling global distribution of aerosols and reactive gases. However, any such prediction is uncertain due to inaccuracies in input data, model parametrisations and lack of resolution. This thesis studies methods for integrating remote sensing and in-situ observations into atmospheric chemistry models with the aim of improving the predictions. Techniques of data assimilation, originally developed for numerical weather prediction, are evaluated for improving regional-scale predictions in two forecast experiments, one targeting the photochemical pollutants ozone (O3) and nitrogen dioxide (NO2), the other targeting sulphur dioxide (SO2). In both cases, assimilation of surface-based air quality monitoring data is found to initially improve the forecast when assessed on monitoring stations not used in assimilation. However, as the forecast length increased, the forecast converged towards the reference simulations where no data assimilation was used. The relaxation time was 6-12 hours for SO2 and NO2 and about 24 hours for O3. An alternative assimilation scheme was tested for SO2. In addition to the initial state of the forecast, the scheme adjusted the gridded emission fluxes based on the observations within the last 24 hours. The improvements due to adjustment of emissions were generally small but, where observed, the improvements persisted throughout the 48 hour forecast. The assimilation scheme was further adapted for estimating emission fluxes in volcanic eruptions. Assimilating retrievals of the Infrared Atmospheric Sounding Interferometer (IASI) instrument allowed reconstructing both the vertical and horizontal profile of SO2 emissions during the 2010 eruption of Eyjafjallaj¨okull in Iceland. As a novel feature, retrievals of plume height were assimilated in addition to the commonly used column density retrievals. The results for Eyjafjallaj¨okull show that the plume height retrievals provide a useful additional constraint in conditions where the vertical distribution would otherwise remain ambiguous. Finally, the thesis presents a rigorous description and evaluation of a numerical scheme for solving the advection equation. The scheme conserves tracer mass and non-negativity, and is therefore suitable for regional and global atmospheric chemistry models. The scheme is particularly adapted for handling discontinuous solutions; for smooth solutions, the scheme is nevertheless found to perform comparably to other state-of-art schemes used in atmospheric models.
  • Saarnio, Karri; Vestenius, Mika; Kyllönen, Katriina (Ilmatieteen laitos - Finnish Meteorological Institute, 2021)
    Raportteja - Rapporter - Reports 2021:2
    Kansallinen ilmanlaadun vertailulaboratorio varmistaa Suomessa tehtävien ilmanlaatumittausten korkean laadun tekemällä ilmanlaatumittausten auditointeja ja vertailumittauksia. Tässä hankkeessa arvioitiin hiukkasmittausten vaatimuksenmukaisuutta keskittyen erityisesti keskimääräisen altistumisindikaattorin (AEI) määrittämiseen käytettävään mittaukseen. Tutkimuksessa arvioitiin Helsingin Kalliossa mitatun PM2,5-altistumisindikaattorin mittauksen tulosten soveltuvuutta ja edustavuutta Suomessa. Havaittiin, että Kallion mittaus edustaa hyvin keskimääräistä pienhiukkasaltistusta sekä pienhiukkaspitoisuuden vuositrendiä Suomessa. Lisäksi vuodesta 2015 eteenpäin Suomen kaupunkitausta-asemilla tehtyjen PM2,5-mittausten keskiarvot niin asemakohtaisesti kuin asemien yhteisenä keskiarvona alittavat kokonaisuudessaan vuoden 2020 keskimääräisen altistumisindikaattorin enimmäisarvon 8,5 µg/m3, jota käytetään altistumisen vähennystavoitteen arvioinnissa. AEI-mittaukseen käytetyn TEOM 1405 -hiukkasmonitorin mittaustuloksia vertailtiin Kalliossa menetelmästandardin SFS-EN 12341:2014 mukaisella vertailumenetelmällä saatuihin tuloksiin. Havaittiin, että AEI-laskentaan käytettävä Kallion TEOM 1405 -laite täyttää niukasti standardissa määritetyn 25 %:n epävarmuusvaatimuksen ja sillä tehtävän mittauksen laatu riittää altistumisindikaattorin määrittämiseen, vaikka vertailtavat pitoisuudet olivat yleisesti ottaen pieniä eikä menetelmästandardin SFS-EN 16450:2017 mukaisen vertailumittauksen pitoisuusvaatimus täyttynyt vertailujaksolla korkeiden pitoisuuksien puuttuessa. Tässä raportissa esitellään myös tulokset jatkuvatoimisille hiukkasmittalaitteille järjestetyistä vertailumittauksista Virolahdella ja Helsingissä sekä PM10- että PM2,5-hiukkaskokojakeelle sekä näiden lisäksi Kuopiossa ja Lahdessa PM2,5-hiukkaskokojakeelle. Vertailumittauksista saatujen tulosten perusteella määritettiin ensimmäistä kertaa korjauskertoimet FIDAS 200 -hiukkasmittalaitteen PM10- ja PM2,5-mittaukselle Suomessa. Tulosten perusteella FIDAS 200 -hiukkasmonitori soveltuu ulkoilman PM10- ja PM2,5-hiukkaskokojakeiden mittaukseen Suomessa käyttäen tässä raportissa esitettyjä korjauskertoimia, vaikkakin on huomioitava, että kertoimet eivät täytä ekvivalenttisuuden osoittamiselle asetettuja vaatimuksia. Kyseisiä kertoimia on kuitenkin suositeltavaa käyttää siihen asti, kunnes ekvivalenttisuus on osoitettu seuraavassa ekvivalenttisuuden osoittamiskampanjassa. Kahta muuta jatkuvatoimista laitetta (SHARP 5030 ja TEOM 1405) verrattiin referenssikeräimeen Virolahdella ja Helsingissä. Havaittiin, että Kuopion vertailumittauksessa 2014–2015 eri laitteille määritetyt korjauskertoimet eivät aina sovellu eri paikoissa ja eri vuodenaikoina PM10- ja PM2,5-hiukkaspitoisuuksien mittauksiin, koska mittauspaikat ja niiden olosuhteet vaihtelevat. Tämän takia vertailulaboratorio esittää ekvivalenttisuuden osoitusta viiden vuoden välein sekä jatkuvaa ohjelmaa käytettävien kertoimien soveltuvuuden osoittamiseksi paikallisilla vertailumittauksilla, joissa jatkuvatoimisten hiukkasmonitorien mittaustuloksia verrataan vertailumenetelmää vastaan eri paikoissa ja vaihtelevissa olosuhteissa jatkuvana kampanjana pitempiaikaisesti, puolesta vuodesta vuoteen kestävillä paikallisilla vertailuilla. Näillä ns. ongoing-mittauksilla voidaan osaltaan varmentaa Suomessa mitattavien PM10- ja PM2,5-hiukkasmittausten laatu ja vertailukelpoisuus myös varsinaisten ekvivalenttisuuden osoittamiseen soveltuvien vertailumittauskampanjoiden välillä.
  • Fung, Pak Lun; Zaidan, Martha; Sillanpää, Salla; Kousa, Anu; Niemi, Jarkko V.; Timonen, Hilkka; Kuula, Joel; Saukko, Erkka; Luoma, Krista Hannele; Petäjä, Tuukka; Tarkoma, Sasu; Kulmala, Markku; Hussein, Tareq (2019)
    Missing data has been a challenge in air quality measurement. In this study, we develop an input-adaptive proxy, which selects input variables of other air quality variables based on their correlation coefficients with the output variable. The proxy uses ordinary least squares regression model with robust optimization and limits the input variables to a maximum of three to avoid overfitting. The adaptive proxy learns from the data set and generates the best model evaluated by adjusted coefficient of determination (adjR2). In case of missing data in the input variables, the proposed adaptive proxy then uses the second-best model until all the missing data gaps are filled up. We estimated black carbon (BC) concentration by using the input-adaptive proxy in two sites in Helsinki, which respectively represent street canyon and urban background scenario, as a case study. Accumulation mode, traffic counts, nitrogen dioxide and lung deposited surface area are found as input variables in models with the top rank. In contrast to traditional proxy, which gives 20–80% of data, the input-adaptive proxy manages to give full continuous BC estimation. The newly developed adaptive proxy also gives generally accurate BC (street canyon: adjR2 = 0.86–0.94; urban background: adjR2 = 0.74–0.91) depending on different seasons and day of the week. Due to its flexibility and reliability, the adaptive proxy can be further extend to estimate other air quality parameters. It can also act as an air quality virtual sensor in support with on-site measurements in the future.
  • Karl, Matthias; Pirjola, Liisa; Karppinen, Ari; Jalkanen, Jukka-Pekka; Ramacher, Martin Otto Paul; Kukkonen, Jaakko (2020)
    Marine traffic in harbors can be responsible for significant atmospheric concentrations of ultrafine particles (UFPs), which have widely recognized negative effects on human health. It is therefore essential to model and measure the time evolution of the number size distributions and chemical composition of UFPs in ship exhaust to assess the resulting exposure in the vicinity of shipping routes. In this study, a sequential modelling chain was developed and applied, in combination with the data measured and collected in major harbor areas in the cities of Helsinki and Turku in Finland, during winter and summer in 2010-2011. The models described ship emissions, atmospheric dispersion, and aerosol dynamics, complemented with a time-microenvironment-activity model to estimate the short-term UFP exposure. We estimated the dilution ratio during the initial fast expansion of the exhaust plume to be approximately equal to eight. This dispersion regime resulted in a fully formed nucleation mode (denoted as Nuc(2)). Different selected modelling assumptions about the chemical composition of Nuc(2) did not have an effect on the formation of nucleation mode particles. Aerosol model simulations of the dispersing ship plume also revealed a partially formed nucleation mode (Nuc(1); peaking at 1.5 nm), consisting of freshly nucleated sulfate particles and condensed organics that were produced within the first few seconds. However, subsequent growth of the new particles was limited, due to efficient scavenging by the larger particles originating from the ship exhaust. The transport of UFPs downwind of the ship track increased the hourly mean UFP concentrations in the neighboring residential areas by a factor of two or more up to a distance of 3600 m, compared with the corresponding UFP concentrations in the urban background. The substantially increased UFP concentrations due to ship traffic significantly affected the daily mean exposures in residential areas located in the vicinity of the harbors.
  • 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.
  • Kukkonen, Jaakko; López-Aparicio, Susana; Segersson, David; Geels, Camilla; Kangas, Leena; Kauhaniemi, Mari; Maragkidou, Androniki; Jensen, Anne; Assmuth, Timo; Karppinen, Ari; Sofiev, Mikhail; Hellén, Heidi; Riikonen, Kari; Nikmo, Juha; Kousa, Anu; Niemi, Jarkko V.; Karvosenoja, Niko; Santos, Gabriela Sousa; Sundvor, Ingrid; Im, Ulas; Christensen, Jesper H.; Nielsen, Ole-Kenneth; Plejdrup, Marlene S.; Nøjgaard, Jacob Klenø; Omstedt, Gunnar; Andersson, Camilla; Forsberg, Bertil; Brandt, Jørgen (European Geosciences Union, 2020)
    Atmospheric Chemistry and Physics 20 7 (2020)
    Residential wood combustion (RWC) is an important contributor to air quality in numerous regions worldwide. This study is the first extensive evaluation of the influence of RWC on ambient air quality in several Nordic cities. We have analysed the emissions and concentrations of PM2.5 in cities within four Nordic countries: in the metropolitan areas of Copenhagen, Oslo, and Helsinki and in the city of Umeå. We have evaluated the emissions for the relevant urban source categories and modelled atmospheric dispersion on regional and urban scales. The emission inventories for RWC were based on local surveys, the amount of wood combusted, combustion technologies and other relevant factors. The accuracy of the predicted concentrations was evaluated based on urban concentration measurements. The predicted annual average concentrations ranged spatially from 4 to 7 µg m−3 (2011), from 6 to 10 µg m−3 (2013), from 4 to more than 13 µg m−3 (2013) and from 9 to more than 13 µg m−3 (2014), in Umeå, Helsinki, Oslo and Copenhagen, respectively. The higher concentrations in Copenhagen were mainly caused by the relatively high regionally and continentally transported background contributions. The annual average fractions of PM2.5 concentrations attributed to RWC within the considered urban regions ranged spatially from 0 % to 15 %, from 0 % to 20 %, from 8 % to 22 % and from 0 % to 60 % in Helsinki, Copenhagen, Umeå and Oslo, respectively. In particular, the contributions of RWC in central Oslo were larger than 40 % as annual averages. In Oslo, wood combustion was used mainly for the heating of larger blocks of flats. In contrast, in Helsinki, RWC was solely used in smaller detached houses. In Copenhagen and Helsinki, the highest fractions occurred outside the city centre in the suburban areas. In Umeå, the highest fractions occurred both in the city centre and its surroundings.
  • Hossein Motlagh, Naser; Zaidan, Martha Arbayani; Fung, Pak Lun; Lagerspetz, Eemil; Aula, Juho Kasimir; Varjonen, Samu; Siekkinen, Matti; Rebeiro-Hargrave, Andrew; Petäjä, Tuukka; Matsumi, Yutaka; Kulmala, Markku; Hussein, Tareq; Nurmi, Petteri; Tarkoma, Sasu (2021)
    Transit activities are a significant contributor to a person's daily exposure to pollutants. Currently obtaining accurate information about the personal exposure of a commuter is challenging as existing solutions either have a coarse monitoring resolution that omits subtle variations in pollutant concentrations or are laborious and costly to use. We contribute by systematically analysing the feasibility of using wearable low-cost pollution sensors for capturing the total exposure of commuters. Through extensive experiments carried out in the Helsinki metropolitan region, we demonstrate that low-cost sensors can capture the overall exposure with sufficient accuracy, while at the same time providing insights into variations within transport modalities. We also demonstrate that wearable sensors can capture subtle variations caused by differing routes, passenger density, location within a carriage, and other factors. For example, we demonstrate that location within the vehicle carriage can result in up to 25% increase in daily pollution exposure -- a significant difference that existing solutions are unable to capture. Finally, we highlight the practical benefits of low-cost sensors as a pollution monitoring solution by introducing applications that are enabled by low-cost wearable sensors.
  • Waldén, Jari; Bergius, Jari; Pohjola, Veijo; Laurila, Sisko; Kuronen, Pirjo; Wemberg, Antti (2008)
    Tutkimuksia - Undersökningar - Studies
  • Kurppa, Mona; Hellsten, Antti; Auvinen, Mikko; Raasch, Siegfried; Vesala, Timo; Jarvi, Leena (2018)
    Buildings and vegetation alter the wind and pollutant transport in urban environments. This comparative study investigates the role of orientation and shape of perimeter blocks on the dispersion and ventilation of traffic-related air pollutants, and the street-level concentrations along a planned city boulevard. A large-eddy simulation (LES) model PALM is employed over a highly detailed representation of the urban domain including street trees and forested areas. Air pollutants are represented by massless and passive particles (non-reactive gases), which are released with traffic-related emission rates. High-resolution simulations for four different city-block-structures are conducted over a 8.2 km domain under two contrasting inflow conditions with neutral and stable atmospheric stratification corresponding the general and wintry meteorological conditions. Variation in building height together with multiple cross streets along the boulevard improves ventilation, resulting in 7-9% lower mean concentrations at pedestrian level. The impact of smaller scale variability in building shape was negligible. Street trees further complicate the flow and dispersion. Notwithstanding the surface roughness, atmospheric stability controls the concentration levels with higher values under stably stratified inflow. Little traffic emissions are transported to courtyards. The results provide urban planners direct information to reduce air pollution by proper structural layout of perimeter blocks.