Browsing by Subject "HELSINKI"

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  • Palonen, V.; Uusitalo, J.; Seppälä, E.; Oinonen, M. (2017)
    Radiocarbon measurements can be used to deduce the proportion of renewable to fossil carbon in materials. While these biofraction measurements are performed routinely on solid and liquid substances, measurements of gaseous samples, such as methane, are still scarce. As a pioneering effort, we have developed a field-capable sampling system for the selective capture of CH4 for radiocarbon-concentration measurements. The system allows for biofraction measurements of methane by accelerator mass spectrometry. In environmental research, radiocarbon measurements of methane can be used for fingerprinting different sources of methane emissions. In metrology and industry, biofraction measurements can be utilized to characterize biogas/natural gas mixtures within gas-line networks. In this work, the portable sampling system is described in detail and reference measurements of biofractions of gaseous fuel samples are presented. Low-concentration (1-ppm-CH4) sampling for environmental applications appears feasible but has not been fully tested at present. This development allows for multitude of future applications ranging from Arctic methane emissions to biogas insertion to gas networks. Published by AIP Publishing.
  • 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.
  • Pakkasela, Johanna; Ilmarinen, Pinja; Honkamäki, Jasmin; Tuomisto, Leena E.; Andersen, Heidi; Piirilä, Päivi; Hisinger-Mölkänen, Hanna; Sovijärvi, Anssi; Backman, Helena; Lundbäck, Bo; Rönmark, Eva; Kankaanranta, Hannu; Lehtimäki, Lauri (2020)
    Background Onset of allergic asthma has a strong association with childhood but only a few studies have analyzed incidence of asthma from childhood to late adulthood in relation to allergy. The purpose of the study was to assess age-specific incidence of allergic and non-allergic asthma. Methods Questionnaires were sent to 8000 randomly selected recipients aged 20-69 years in Finland in 2016. The response rate was 52.3% (n = 4173). The questionnaire included questions on e.g. atopic status, asthma and age at asthma diagnosis. Asthma was classified allergic if also a physician-diagnosed allergic rhinitis was reported. Results The prevalence of physician-diagnosed asthma and allergic rhinitis were 11.2 and 17.8%, respectively. Of the 445 responders with physician-diagnosed asthma, 52% were classified as allergic and 48% as non-allergic. Median ages at diagnosis of allergic and non-allergic asthma were 19 and 35 years, respectively. Among subjects with asthma diagnosis at ages 0-9, 10-19, 20-29, 30-39, 40-49, 50-59 and 60-69 years, 70, 62, 58, 53, 38, 19 and 33%, respectively, were allergic. For non-allergic asthma, the incidence rate was lowest in children and young adults (0.7/1000/year). It increased after middle age and was highest in older age groups (2.4/1000/year in 50-59 years old). Conclusions The incidence of allergic asthma is highest in early childhood and steadily decreases with advancing age, while the incidence of non-allergic asthma is low until it peaks in late adulthood. After approximately 40 years of age, most of the new cases of asthma are non-allergic.
  • Karhu, Juho; Kuula, Joel; Virkkula, Aki; Timonen, Hilkka; Vainio, Markku; Hieta, Tuomas (2021)
    Photoacoustic detection is a sensitive method for measurement of light-absorbing particles directly in the aerosol phase. In this article, we demonstrate a new sensitive technique for photoacoustic aerosol absorption measurements using a cantilever microphone for the detection of the photoacoustic signal. Compared to conventional diaphragm microphones, a cantilever offers increased sensitivity by up to two orders of magnitude. The measurement setup uses a photoacoustic cell from Gasera PA201 gas measurement system, which we have adapted for aerosol measurements. Here we reached a noise level of 0.013 Mm(-1) (one standard deviation) with a sampling time of 20 s, using a simple single-pass design without a need for a resonant acoustic cell. The sampling time includes 10 s signal averaging time and 10 s sample exchange, since the photoacoustic cell is designed for closed cell operation. We demonstrate the method in measurements of size-selected nigrosin particles and ambient black carbon. Due to the exceptional sensitivity, the technique shows great potential for applications where low detection limits are required, for example size-selected absorption measurements and black carbon detection in ultra clean environments.
  • Jansson, A. H.; Savikko, N.; Kautiainen, H.; Roitto, H. -M.; Pitkälä, K. H. (2020)
  • Björkqvist, Johan; Kuula, Juho; Kuula, Liisa; Nurhonen, Markku; Hovi, Petteri; Räikkönen, Katri; Pesonen, Anu; Kajantie, Eero (2020)
    Chronotype is the temporal preference for activity and sleep during the 24 h day and is linked to mental and physical health, quality of life, and mortality. Later chronotypes, so-called “night owls”, consistently display poorer health outcomes than “larks”. Previous studies have suggested that preterm birth (<37 weeks of gestation) is associated with an earlier chronotype in children, adolescents, and young adults, but studies beyond this age are absent. Our aim was to determine if adults born preterm at very low birth weight (VLBW, ≤1500 g) display different chronotypes than their siblings. We studied VLBW adults, aged 29.9 years (SD 2.8), matched with same-sex term-born siblings as controls. A total of 123 participants, consisting of 53 sibling pairs and 17 unmatched participants, provided actigraphy-derived data on the timing, duration, and quality of sleep from 1640 nights (mean 13.3 per participant, SD 2.7). Mixed effects models provided estimates and significance tests. Compared to their siblings, VLBW adults displayed 27 min earlier sleep midpoint during free days (95% CI: 3 to 51 min, p =.029). This was also reflected in the timing of falling asleep, waking up, and sleep-debt corrected sleep midpoint. The findings were emphasized in VLBW participants born small for gestational age. VLBW adults displayed an earlier chronotype than their siblings still at age 30, which suggests that the earlier chronotype is an enduring individual trait not explained by shared family factors. This preference could provide protection from risks associated with preterm birth.
  • Kuurne (nee Ketokivi), Kaisa; Vieno, Atte (2022)
    This article continues the conceptual work of developing a process-oriented perspective on belonging by taking up the active engagement of affiliation (and disaffiliation) as an undertheorised yet necessary aspect of accomplishing belonging. In developing the concept we draw on Marx's notion of work as material activity in forms of life and the sociological concepts of face-work and emotion work. We conceptualise belonging work as relational work concerned with shaping situational interactions; webs of relationships; social boundaries; and materials and rhythms as dimensions of belonging. This work is conditioned by social categorisations and patterns of inclusion and exclusion through which it takes place in relation to specific forms of life. The concept of belonging work offers a theoretically integrative and sensitising concept that highlights the relational dynamics of belonging, providing insight and inspiration to social researchers inquiring into the work of belonging and its associated social consequences throughout the research process.
  • Axelsson, Malin; Ilmarinen, Pinja; Backman, Helena; Ekerljung, Linda; Hedman, Linnea; Langhammer, Arnulf; Lindberg, Anne; Lindqvist, Ari; Nwaru, Bright I.; Pallasaho, Paula; Sovijärvi, Anssi; Vähätalo, Iida; Kankaanranta, Hannu; Hisinger-Mölkänen, Hanna; Piirilä, Päivi; Ronmark, Eva (2021)
    Objective:To investigate the current prevalence of physician-diagnosed obstructive airway diseases by respiratory symptoms and by sex in Sweden and Finland. Method:In 2016, a postal questionnaire was answered by 34,072 randomly selected adults in four study areas: Vastra Gotaland and Norrbotten in Sweden, and Seinajoki-Vaasa and Helsinki in Finland. Results:The prevalence of asthma symptoms was higher in Norrbotten (13.2%), Seinajoki-Vaasa (14.8%) and Helsinki (14.4%) than in Vastra Gotaland (10.7%), and physician-diagnosed asthma was highest in Norrbotten (13.0%) and least in Vastra Gotaland (10.1%). Chronic productive cough was most common in the Finnish areas (7.7-8.2% versus 6.3-6.7%) while the prevalence of physician-diagnosed chronic bronchitis (CB) or chronic obstructive pulmonary disease (COPD) varied between 1.7 and 2.7% in the four areas. Among individuals with respiratory symptoms, the prevalence of asthma was most common in Norrbotten, while a diagnosis of COPD or CB was most common in Vastra Gotaland and Seinajoki-Vaasa. More women than men with respiratory symptoms reported a diagnosis of asthma in Sweden and Seinajoki-Vaasa but there were no sex differences in Helsinki. In Sweden, more women than men with symptoms of cough or phlegm reported a diagnosis of CB or COPD, while in Finland the opposite was found. Conclusion:The prevalence of respiratory symptoms and corresponding diagnoses varied between and within the countries. The proportion reporting a diagnosis of obstructive airway disease among individuals with respiratory symptoms varied, indicating differences in diagnostic patterns both between areas and by sex.
  • Kangasniemi, Oskari; Kuuluvainen, Heino; Heikkilä, Joni; Pirjola, Liisa; Niemi, Jarkko V.; Timonen, Hilkka; Saarikoski, Sanna; Rönkkö, Topi; Dal Maso, Miikka (2019)
    Traffic is a major source of ultrafine aerosol particles in urban environments. Recent studies show that a significant fraction of traffic-related particles are only few nanometers in diameter. Here, we study the dispersion of this nanocluster aerosol (NCA) in the size range 1.3-4 nm. We measured particle concentrations near a major highway in the Helsinki region of Finland, varying the distance from the highway. Additionally, modelling studies were performed to gain further information on how different transformation processes affect NCA dispersion. The roadside measurements showed that NCA concentrations fell more rapidly than the total particle concentrations, especially during the morning. However, a significant amount of NCA particles remained as the aerosol population evolved. Modelling studies showed that, while dilution is the main process acting on the total particle concentration, deposition also had a significant impact. Condensation and possibly enhanced deposition of NCA were the main plausible processes explaining why dispersion is faster for NCA than for total particle concentration, while the effect of coagulation on all size ranges was small. Based on our results, we conclude that NCA may play a significant role in urban environments, since, rather than being scavenged by larger particles, NCA particles remain in the particle population and grow by condensation.
  • Viippola, Viljami; Yli-Pelkonen, Vesa; Järvi, Leena; Kulmala, Markku; Setälä, Heikki (2020)
    Trees and other vegetation have been advocated as a mitigation measure for urban air pollution mainly due to the fact that they passively filter particles from the air. However, mounting evidence suggests that vegetation may also worsen air quality by slowing the dispersion of pollutants and by producing volatile organic compounds that contribute to formation of ozone and other secondary pollutants. We monitored nanoparticle (>10 nm) counts along distance gradients away from major roads along paired transects across open and forested landscapes in Baltimore (USA), Helsinki (Finland) and Shenyang (China) − i.e. sites in three biomes with different pollution levels − using condensation particle counters. Mean particle number concentrations averaged across all sampling sites were clearly reduced (15 %) by the presence of forest cover only in Helsinki. For Baltimore and Shenyang, levels showed no significant difference between the open and forested transects at any of the sampling distances. This suggests that nanoparticle deposition on trees is often counterbalanced by other factors, including differing flow fields and aerosol processes under varying meteorological conditions. Similarly, consistent differences in high frequency data patterns between the transects were detected only in Helsinki. No correlations between nanoparticle concentrations and solar radiation or local wind speed as affecting nanoparticle abundances were found, but they were to some extent associated with canopy closure. These data add to the accumulating evidence according to which trees do not necessarily improve air quality in near-road environments.
  • Fung, Pak L.; Zaidan, Martha A.; Timonen, Hilkka; Niemi, Jarkko V.; Kousa, Anu; Kuula, Joel; Luoma, Krista; Tarkoma, Sasu; Petäjä, Tuukka; Kulmala, Markku; Hussein, Tareq (2021)
    Air quality prediction with black-box (BB) modelling is gaining widespread interest in research and industry. This type of data-driven models work generally better in terms of accuracy but are limited to capture physical, chemical and meteorological processes and therefore accountability for interpretation. In this paper, we evaluated different white-box (WB) and BB methods that estimate atmospheric black carbon (BC) concentration by a suite of observations from the same measurement site. This study involves data in the period of 1st January 2017–31st December 2018 from two measurement sites, from a street canyon site in Mäkelänkatu and from an urban background site in Kumpula, in Helsinki, Finland. At the street canyon site, WB models performed (R² = 0.81–0.87) in a similar way as the BB models did (R² = 0.86–0.87). The overall performance of the BC concentration estimation methods at the urban background site was much worse probably because of a combination of smaller dynamic variability in the BC values and longer data gaps. However, the difference in WB (R²= 0.44–0.60) and BB models (R² = 0.41–0.64) was not significant. Furthermore, the WB models are closer to physics-based models, and it is easier to spot the relative importance of the predictor variable and determine if the model output makes sense. This feature outweighs slightly higher performance of some individual BB models, and inherently the WB models are a better choice due to their transparency in the model architecture. Among all the WB models, IAP and LASSO are recommended due to its flexibility and its efficiency, respectively. Our findings also ascertain the importance of temporal properties in statistical modelling. In the future, the developed BC estimation model could serve as a virtual sensor and complement the current air quality monitoring.
  • Yli-Pelkonen, Vesa Johannes; Viippola, Juho Viljami; Kotze, David Johannes; Setälä, Heikki Martti (2017)
    Trees are believed to improve air quality, thus providing an important ecosystem service for urban inhabitants. However, empirical evidence on the beneficial effects of urban vegetation on air quality at the local level and in boreal climatic regions is scarce. We studied the influence of greenbelt-type forest patches on NO2 levels (i) in front of, (ii) inside and (iii) behind greenbelts next to major roads in the Helsinki Metropolitan Area, Finland, during summer and winter using passive collectors. Concentrations of NO2 were significantly higher in front of greenbelts compared to road sides without greenbelts. The more trees there were inside greenbelts the higher the NO2 level in front of greenbelts, likely due to the formation of a recirculation zone of air flow in front of greenbelts. Similarly, NO2 levels were higher inside greenbelts than in open areas without them, likely due to reduced air flow inside greenbelts. NO2 levels behind greenbelts were similar to those detected at the same distance from the road but without greenbelts. Our results suggest that, regardless of season, roadside greenbelts of mostly broadleaf trees do not reduce NO2 levels in near-road environments, but can result in higher NO2 levels in front of and inside greenbelts.
  • Mladenovic, Milos N.; Haavisto, Noora (2021)
    Mobility-as-a-service (MaaS) is still largely under development, with high uncertainties of its societal implications. This development is happening across sectoral, multi-layered, and multi-actor networks. Previous case studies on understanding networked governance of MaaS inform us that there is a range of challenges in the current institutional arrangements, lack of shared MaaS vision, divergent interests, and even conflicts over roles and responsibilities. These case studies have used analytical frameworks based on socio-technical transitions theory, complemented with theories from institutional and business studies. This study focuses on Finland, aiming to provide additional insights about perspectives of non-commercial actors. In particular, we provide a more sophisticated understanding of underlying reasons for conflict and lack of cooperation concerning an understanding of MaaS, its implications, and associated governance actions. The applied analytical framework is building upon concepts from the philosophy and sociology of emerging technology, as well as the contemporary political theory of Chantal Mouffe. Interview findings from seventeen non-commercial organisations have been classified into five categories, namely definitions, operational and business aspects, user perspectives, systemic effects, and governance. Discussion of these interview findings focuses on the interpretative flexibility of MaaS and governance processes in the context of inherent conflict in the value-laden mobility domain. The paper concludes with outlining directions for further synthesis in developing analytical frameworks for studies of governance and responsible innovation in the domain of emerging mobility technologies.
  • Kaseva, Nina; Wehkalampi, Karoliina; Strang-Karlsson, Sonja; Salonen, Minna; Pesonen, Anu-Katriina; Räikkönen, Katri; Tammelin, Tuija; Hovi, Petteri; Lahti, Jari; Heinonen, Kati; Jarvenpaa, Anna-Liisa; Andersson, Sture; Eriksson, Johan G.; Kajantie, Eero (2012)
  • Väisänen, Tuomas Lauri Aleksanteri; Järv, Olle; Toivonen, Tuuli; Hiippala, Tuomo (2022)
    Globalization, urbanization and international mobility have led to increasingly diverse urban populations. Compared to traditional traits for measuring urban diversity, such as ethnicity and country of origin, the role of language remains underexplored in understanding diversity, interactions between different groups and socio-spatial segregation. In this article, we analyse language use in the Helsinki Metropolitan Area by combining individual-level register data, socio-economic grid database, mobile phone and social media data to understand spatio-temporal patterns of linguistic diversity better. We measured linguistic diversity using metrics developed in the fields of ecology and information theory, and performed spatial clustering and regression analyses to explore the spatio-temporal patterns of linguistic diversity. We found spatial and temporal differences between register and social media data, show that linguistic diversity is influenced by the physical and socio-economic environment, and identified areas where different linguistic groups are likely to interact. Our results provide insights for urban planning and understanding urban diversity through linguistic information. As global urbanization, international migration and refugee flows and climate change drive diverse populations into cities, understanding urban diversity and its implications for urban planning and sustainability become increasingly important.
  • Bellucco, Veronica; Marras, Serena; Grimmond, C. Susan B.; Järvi, Leena; Sirca, Costantino; Spano, Donatella (2017)
    The biogenic CO2 surface atmosphere exchange is investigated and linked to vegetation cover fraction for seven sites (three urban and four non-urban) in the northern hemisphere. The non-rectangular hyperbola (NRH) is used to analyse the light-response curves during period of maximum ecophysiological processes, and to develop two models to simulate biogenic vertical CO2 fluxes. First, a generalised set of NRH coefficients is calculated after linear regression analysis across urban and non-urban ecosystems. Second, site-specific NRH coefficients are calculated for a suburban area in Helsinki, Finland. The model includes a temperature driven equation to estimate ecosystem respiration, and variation of leaf area index to modulate emissions across the year. Eddy covariance measured CO2 fluxes are used to evaluate the two models at the suburban Helsinki site and the generalised model also in Mediterranean ecosystem. Both models can simulate the mean daily trend at monthly and seasonal scales. Modelled data typically fall within the range of variability of the observations (differences of the order of 10%). Additional information improves the models performance, notably the selection of the most vegetated wind direction in Helsinki. The general model performs reasonably well during daytime but it tends to underestimate CO2 emissions at night. This reflects the model capability to catch photosynthesis processes occurring during the day, and the importance of the gross primary production (GPP) in modifying the net ecosystem exchange (NEE) of urban sites with different vegetation cover fraction. Therefore, the general model does not capture the differences in ecosystem respiration that skew nocturnal fluxes. The relation between the generalised NRH plateau parameter and vegetation cover improves (R-2 from 0.7 to 0.9) when only summer weekends with wind coming from the most vegetated sector in Helsinki and well-watered conditions for Mediterranean sites are included in the analysis. In the local model, the inclusion of a temperature driven equation for estimating the ecosystem respiration instead of a constant value, does not improve the long-term simulations. In conclusion, both the general and local models have significant potential and offer valid modelling options of biogenic components of carbon exchange in urban and non-urban ecosystems.(C) 2016 Elsevier B.V. All rights reserved.
  • Auvinen, Mikko; Järvi, Leena; Hellsten, Antti; Rannik, Ullar; Vesala, Timo (2017)
    Conventional footprint models cannot account for the heterogeneity of the urban landscape imposing a pronounced uncertainty on the spatial interpretation of eddycovariance (EC) flux measurements in urban studies. This work introduces a computational methodology that enables the generation of detailed footprints in arbitrarily complex urban flux measurements sites. The methodology is based on conducting high-resolution large-eddy simulation (LES) and Lagrangian stochastic (LS) particle analysis on a model that features a detailed topographic description of a real urban environment. The approach utilizes an arbitrarily sized target volume set around the sensor in the LES domain, to collect a dataset of LS particles which are seeded from the potential source area of the measurement and captured at the sensor site. The urban footprint is generated from this dataset through a piecewise postprocessing procedure, which divides the footprint evaluation into multiple independent processes that each yield an intermediate result. These results are ultimately selectively combined to produce the final footprint. The strategy reduces the computational cost of the LES-LS simulation and incorporates techniques to account for the complications that arise when the EC sensor is mounted on a building instead of a conventional flux tower. The presented computational framework also introduces a result assessment strategy which utilizes the obtained urban footprint together with a detailed land cover type dataset to estimate the potential error that may arise if analytically derived footprint models were employed instead. The methodology is demonstrated with a case study that concentrates on generating the footprint for a building-mounted EC measurement station in downtown Helsinki, Finland, under the neutrally stratified atmospheric boundary layer.
  • van Dinther, D.; Wood, C. R.; Hartogensis, O. K.; Nordbo, A.; O'Connor, E. J. (2015)
    In this study, the crosswind (wind component perpendicular to a path, U-perpendicular to) is measured by a scintillometer and estimated with Doppler lidar above the urban environment of Helsinki, Finland, for 15 days. The scintillometer allows acquisition of a path-averaged value of U-perpendicular to ((U-perpendicular to) over bar), while the lidar allows acquisition of path-resolved U-perpendicular to (U-perpendicular to(x), where x is the position along the path). The goal of this study is to evaluate the performance of scintillometer estimates for conditions under which U-perpendicular to(x) is variable. Two methods are applied to estimate (U-perpendicular to) over bar from the scintillometer signal: the cumulative-spectrum method (relies on scintillation spectra) and the look-up-table method (relies on time-lagged correlation functions). The values of (U-perpendicular to) over bar of both methods compare well with the lidar estimates, with root-mean-square deviations of 0.71 and 0.73 ms(-1). This indicates that, given the data treatment applied in this study, both measurement technologies are able to obtain estimates of (U-perpendicular to) over bar in the complex urban environment. The detailed investigation of four cases indicates that the cumulative-spectrum method is less susceptible to a variable U-perpendicular to (x) /than the look-up-table method. However, the look-up-table method can be adjusted to improve its capabilities for estimating (U-perpendicular to) over bar under conditions under for which U-perpendicular to (x) is variable.
  • Lassmann-Klee, Paul; Piirilä, Päivi L.; Brumpton, Ben; Larsson, Matz; Sundblad, Britt-Marie; Põlluste, Jaak; Juusela, Maria; Rouhos, Annamari; Meren, Mari; Lindqvist, Ari; Kankaanranta, Hannu; Backman, Helena; Langhammer, Arnulf; Ronmark, Eva; Lundbäck, Bo; Sovijärvi, Anssi (2020)
    The prevalence of asthma is higher in Sweden and Finland than in neighbouring eastern countries including Estonia. Corresponding difference in bronchial eosinophilic inflammation could be studied by FENO measurements. We aimed to compare FENO in adult general populations of Sweden, Finland, and Estonia, to test the plausibility of the west-east disparity hypothesis of allergic diseases. We conducted clinical interviews (N = 2658) with participants randomly selected from the general populations in Sweden (Stockholm and Örebro), Finland (Helsinki), and Estonia (Narva and Saaremaa), and performed FENO (n = 1498) and skin prick tests (SPT) in 1997–2003. The median (interquartile range) of FENO (ppb) was 15.5 (9.3) in Sweden, 15.4 (13.6) in Finland and 12.5 (9.6) in Estonia. We found the lowest median FENO values in the Estonian centres Saaremaa 13.1 (9.5) and Narva 11.8 (8.6). In the pooled population, asthma was associated with FENO ≥25 ppb, odds ratio (OR) 3.91 (95% confidence intervals: 2.29–6.32) after adjusting for SPT result, smoking, gender and study centre. A positive SPT test increased the likelihood of asthma OR 3.19 (2.02–5.11). Compared to Saaremaa, the likelihood of having asthma was higher in Helsinki OR 2.40 (1.04–6.02), Narva OR 2.45 (1.05–6.19), Örebro OR 3.38 (1.59–8.09), and Stockholm OR 5.54 (2.18–14.79). There was a higher prevalence of asthma and allergic airway inflammation in adult general populations of Sweden and Finland compared to those of Estonia. Atopy and elevated FENO level were independently associated with an increased risk of asthma. In conclusion, the findings support the earlier west-east disparity hypothesis of allergic diseases.
  • Björkqvist, Johan; Pesonen, Anu-Katriina; Kuula, Liisa; Matinolli, Hanna-Maria; Lano, Aulikki; Sipola-Leppanen, Marika; Tikanmaki, Marjaana; Wolke, Dieter; Jarvelin, Marjo-Riitta; Eriksson, Johan G.; Andersson, Sture; Vaarasmaki, Marja; Heinonen, Kati; Raikkonen, Katri; Hovi, Petteri; Kajantie, Eero (2018)
    A preference for eveningness (being a "night owl") and preterm birth ( Circadian preference was measured among 594 young adults (mean age 24.3 years, SD 1.3) from two cohorts: the ESTER study and the Arvo Ylppo Longitudinal Study. We compared 83 participants born early preterm (= 37 weeks, n = 346). We also compared very low birth weight (VLBW, There were no consistent differences across the study groups in sleep midpoint. As compared with those born at term, the mean differences in minutes:seconds and 95% confidence intervals for the sleep midpoint were: early preterm weekdays 11:47 (-834 to 32:08), early preterm weekend 4:14 (-19:45 to 28:13), late preterm weekdays -10:28 (-26:16 to 5:21), and late preterm weekend -1:29 (-20:36 to 17:37). There was no difference in sleep timing between VLBW-participants and controls either. The distribution of chronotype in the MEQ among all participants was 12.4% morningness, 65.4% intermediate, and 22.2% eveningness. The distribution of the subjective chronotype class did not differ between the three gestational age groups (p = 0.98). The linear regression models did not show any influence of gestational age group or VLBW status on the MES (all p > 0.5). We found no consistent differences between adults born early or late preterm and those born at term in circadian preference. The earlier circadian preference previously observed in those born smallest is unlikely to extend across the whole range of preterm birth.