Problematic situations related to social media use and competencies to prevent them: results of a Delphi study

A three-round Delphi method was used to study the problematic situations that adolescents may encounter when using the social media, and the competencies needed to address these situations. A panel of Finnish experts (N = 22) provided an open-ended list of problematic situations and competencies in 2020-2021. These were then evaluated and ranked according to their significance. The experts provided an information-rich list of both problematic situations and competencies. Finally, 16 problematic situations and 19 competencies were ranked in order of importance by the experts. The most important problematic situations were direct and indirect cyberbullying and sexual harassment. The most important competencies were the ability to act responsibly, knowing what kinds of activity are prohibited, and knowing whom to contact on exposure to cyberbullying or harassment. The findings can be used in developing policies, recommendations, and solutions aimed at counteracting the harmful effects of social media on wellbeing during adolescence.

What Counteracts Problematic Social Media Use in Adolescence? A Cross-National Observational Study

PURPOSE

Social media use has increased rapidly during the past decade, raising concerns about adolescents who display problematic social media use (PSMU), as indicated by addiction-like symptoms (e.g., preoccupation, tolerance). We aimed to assess the extent to which an individual resource (health literacy), and social resources (friend support and family support), moderated the association between a range of individual characteristics (gender, age, family affluence, and depressive feelings) and PSMU; also the association between PSMU and health outcomes (self-rated health, life satisfaction, and sleep difficulties), both cross-nationally and nationally.

METHODS

Our sample included 22,226 adolescents from six European countries. We used data from the Health Behaviour in School-aged Children cross-sectional survey (2017/2018). Random-effects models and moderator analyses were applied.

RESULTS

Six moderations were found, with the resources moderating the association between individual characteristics and PSMU. One moderation emerged cross-nationally, namely that a higher level of family support was associated with a lower likelihood of PSMU, especially among adolescents who did not have frequent depressive feelings. In addition, five national moderations were identified. For example, a higher level of health literacy was associated with a lower likelihood of PSMU among Finnish girls. The resources were also found to moderate the association between PSMU and health outcomes, with two moderations emerging cross-nationally. For instance, a higher level of family support was related to higher self-rated health, especially among problematic users. In addition, nine national moderations were identified; these included a higher level of health literacy being associated with having less sleep difficulties, especially among problematic users in Germany.

DISCUSSION

In adolescence, health literacy, family support, and friend support have the potential to moderate the association between individual characteristics and PSMU, and between PSMU and health outcomes, cross-nationally and nationally. We recommend the use of universal and targeted interventions to promote individual and social resources to counteract PSMU.

Online health information-seeking behaviour and mental well-being among Finnish higher education students during COVID-19

Online health information-seeking behaviour has increased since the World Health Organization declared COVID-19 a global pandemic in March 2020. This study examined whether health-related information on COVID-19 searched on the internet was associated with mental well-being among higher education students. A cross-sectional internet survey was conducted among 18- to 34-year-old students in Finland (N = 2976; mean age 24.61 years and median 24) in the spring of 2020. The data were analysed using descriptive statistics, Pearson's chi-square tests, Kruskal-Wallis nonparametric H tests, and a two-way ANOVA. The results indicated that most students (86% of females, 82% of males) used the internet to search for information on COVID-19. Students' self-perceived abilities to determine the relevance of online information on COVID-19 were associated with mental well-being.

The development and cross-national validation of the short health literacy for school-aged children (HLSAC-5) instrument

Health literacy is an asset for and indicator of adolescents' health and wellbeing, and should therefore be monitored and addressed across countries. This study aimed to develop and validate a shorter version of the original 10-item health literacy for school-aged children instrument in a cross-national context, using data from the health behaviour in school-aged children 2017/18 survey. The data were obtained from 25 425 adolescents (aged 13 and 15 years) from seven European countries. Determination was made of the best item combination to form a shorter version of the health literacy instrument. Thereafter, the structural validity, reliability, measurement invariance, and criterion validity of the new 5-item instrument were examined. Confirmatory factor analysis showed a good model fit to the data across countries and in the total sample, confirming the structural validity (CFI = 0.995, TLI = 0.989, SRMR = 0.011, RMSEA = 0.031). The internal consistency of the instrument was at a good level across countries (α = 0.87-0.98), indicating that the instrument provided reliable scores. Configural and metric invariance was established across genders, ages, and countries. Scalar invariance was achieved for age and gender groups, but not between countries. This indicated that the factor structure of the scale was similar, but that there were differences between the countries in health literacy levels. Regarding criterion validity, structural equation modelling showed a positive association between health literacy and self-rated health in all the participating countries. The new instrument was found to be valid and reliable for the purposes of measuring health literacy among adolescents in a cross-national context.

Patient satisfaction - results of cluster analysis of finnish patients

BACKGROUND

Healthcare providers must understand patients' expectations and perceptions of the care they receive to provide high-quality care. The purpose of this study is to identify and analyse different clusters of patient satisfaction with the quality of care at Finnish acute care hospitals.

METHODS

A cross-sectional design was applied. The data were collected in 2017 from three Finnish acute care hospitals with the Revised Humane Caring Scale (RHCS) as a paper questionnaire, including six background questions and six subscales. The k-means clustering method was used to define and analyse clusters in the data. The unit of analysis was a health system encompassing inpatients and outpatients. Clusters revealed the common characteristics shared by the different groups of patients.

RESULTS

A total of 1810 patients participated in the study. Patient satisfaction was categorised into four groups: dissatisfied (n = 58), moderately dissatisfied (n = 249), moderately satisfied (n = 608), and satisfied (n = 895). The scores for each subscale were significantly above average in the satisfied patient group. The dissatisfied and moderately dissatisfied patient groups reported scores for all six subscales that were clearly below the average value. The groups significantly differed in terms of hospital admission (p = .013) and living situation (p = .009). Patients representing the dissatisfied and moderately dissatisfied groups were acutely admitted more frequently than patients in other groups and were more likely to live alone than satisfied and moderately satisfied patients.

CONCLUSION

The results mostly demonstrated high levels of patient satisfaction; however, the perceptions of minority populations of dissatisfied patients should be assessed to identify shortcomings in the care provided. More attention should be paid to acutely admitted patients who are living alone and the pain and apprehension management of all patients.

Mental health profiles of Finnish adolescents before and after the peak of the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic has had implications for adolescents' interpersonal relationships, communication patterns, education, recreational activities and well-being. An understanding of the impact of the pandemic on their mental health is crucial in measures to promote the post-pandemic recovery. Using a person-centered approach, the current study aimed to identify mental health profiles in two cross-sectional samples of Finnish adolescents before and after the peak of the pandemic, and to examine how socio-demographic and psychosocial factors, academic expectations, health literacy, and self-rated health are associated with the emerging profiles.

METHODS AND FINDINGS

Survey data from the Health Behaviour in School-aged Children (HBSC) study conducted in Finland in 2018 (N = 3498, age M = 13.44) and 2022 (N = 3838, age M = 13.21) were analyzed. A four-profile model using cluster analysis was selected for both samples. In Sample 1, the identified profiles were (1) "Good mental health", (2) "Mixed psychosocial health", (3) "Somatically challenged", and (4) "Poor mental health". In Sample 2, the identified profiles were (1) "Good mental health", (2) "Mixed psychosomatic health", (3) "Poor mental health and low loneliness", and (4) "Poor mental health and high loneliness". The results of the mixed effect multinomial logistic regression analysis showed that in both samples, being a girl and reporting lower maternal monitoring; lower family, peer, and teacher support; higher intensity of online communication; a less positive home atmosphere and school climate; and poor self-rated health were most strongly linked to belonging to a poorer mental health profile. In addition, in Sample 2, low subjective health literacy was a key factor associated with poorer mental health profiles, and teacher support was more important than before COVID.

CONCLUSIONS

The current study stresses the importance of identifying those vulnerable to developing poor mental health. To maximize post-pandemic recovery, the role of schools, especially teacher support and health literacy, along with the factors that remained important over time should be taken into account in public health and health promotion interventions.

Systematic education has a positive impact on nurses' evidence-based practice: Intervention study results

AIMS

To evaluate how an education program on evidence-based practice (EBP) affected nurses´ knowledge, practices, and attitudes related to EBPs in patient care.

METHODS

Nurses of one Finnish university hospital participated in two separate EBP education programs in 2016-2017 and 2018-2019. Data was collected by a questionnaire given before and after each program. Reliable instruments for measuring EBP were used: The Evidence-Based Practice Questionnaire (24 items) and the Attitudes to Evidence-Based Practice Questionnaire (17 items). Means and frequencies were evaluated with the Mann-Whitney U test and linear regression.

RESULTS

Nurses reported that their EBP practice, skills and the Work based on EBPs improved substantially after the education program. We found that scores on the Work based on EBPs and the attitudes towards EBP could predict the nurses' overall self-evaluations of practices, attitudes, and skills.

DISCUSSION

EBP education affects positively on implementation of nurses' practices and skills. There is still a need to change attitudes towards evidence based practice. IMPLICATIONS FOR PRACTICE, RESEARCH, POLICY, MANAGEMENT, AND EDUCATION: Organizations need to maintain and develop efficient, attractive EBP educational programs to promote lifelong learning.

CONCLUSIONS

When designing EBP educational content, it is crucial to teach participants to develop evidence-based methods and consider how to implement them in practice.

Health literacy among adolescents: summary of some key findings from ten European countries

Introduction

In research on disparities, the concept of health literacy (HL) as a set of competencies to promote and sustain health may help in understanding the disparities better and in addressing avoidable and unfair health disparities. The presentation will present some key findings on adolescents’ HL levels in ten European countries, and how HL mediates and moderates between various background factors and health outcomes.

Methods

Data consisted of cross-sectional data from Health Behaviour in School-aged Children (HBSC) study from year 2017/18 of ten European countries (Austria, Belgium (Fl), Czechia, England, Estonia, Finland, Germany, Macedonia, Poland, and Slovakia). Data (n = 14,590 - 22,291) of 13- and 15-year-old pupils were used. Indicators include background variables (e.g. age, gender), Health literacy, Health indicators (e.g. self-rated health (SRH) and problematic social media use (PSMU)). Analysis include (1) Mediator analysis (with Mplus): pearson correlation coefficients, path models (Mplus 7.3 and Maximum Likelihood estimator) and (2) random effects models and moderator analyses (with R-sofware).

Findings

HL is an independent factor explaining disparities in health (e.g. SRH), and a mediator as well as a moderator between health outcomes and background factors. Based on the national analyses HL had significant main effects in every country, but group level differences emerged only in some countries. For instance, in Finland and Belgium, among girls HL lowered the likelihood to problematic social media use, but not among boys.

Discussion

HL is of use in understanding and tackling health disparities among adolescents. Results confirm the need to adopt the principles of proportionate universalism when promoting HL among adolescents to avoid widening the disparities within population groups. Also, country-specific health literacy interventions are needed to secure equity in opportunities of different population groups to benefit from the HL interventions.

Observed coupling between air mass history, secondary growth of nucleation mode particles and aerosol pollution levels in Beijing

Atmospheric aerosols have significant effects on the climate and on human health. New particle formation (NPF) is globally an important source of aerosols but its relevance especially towards aerosol mass loadings in highly polluted regions is still controversial. In addition, uncertainties remain regarding the processes leading to severe pollution episodes, concerning e.g. the role of atmospheric transport. In this study, we utilize air mass history analysis in combination with different fields related to the intensity of anthropogenic emissions in order to calculate air mass exposure to anthropogenic emissions (AME) prior to their arrival at Beijing, China. The AME is used as a semi-quantitative metric for describing the effect of air mass history on the potential for aerosol formation. We show that NPF events occur in clean air masses, described by low AME. However, increasing AME seems to be required for substantial growth of nucleation mode (diameter < 30 nm) particles, originating either from NPF or direct emissions, into larger mass-relevant sizes. This finding assists in establishing and understanding the connection between small nucleation mode particles, secondary aerosol formation and the development of pollution episodes. We further use the AME, in combination with basic meteorological variables, for developing a simple and easy-to-apply regression model to predict aerosol volume and mass concentrations. Since the model directly only accounts for changes in meteorological conditions, it can also be used to estimate the influence of emission changes on pollution levels. We apply the developed model to briefly investigate the effects of the COVID-19 lockdown on PM_2.5 concentrations in Beijing. While no clear influence directly attributable to the lockdown measures is found, the results are in line with other studies utilizing more widely applied approaches.

The role of health literacy in the association between academic performance and substance use

BACKGROUND

To address social inequalities in adolescent substance use and consequent disparities in health, it is important to identify the mechanisms of the association between substance use and academic performance. We study the role of health literacy (HL) in the association between academic performance and weekly smoking, monthly alcohol use and cannabis ever-use among adolescents in Europe.

METHODS

SILNE-R school survey data, which was collected in 2016-17 with paper-and-pencil-method from Hanover (GE), Amersfoort (NL) and Tampere (FI), were used (N = 5088, age 13-19). Health Literacy for School-aged Children instrument was used to assess students' HL. Logistic regression analyzed the association of substance use with academic performance and HL, separately and in the same model. Linear and multinomial logistic regression analyzed the association between academic performance and HL.

RESULTS

Poor academic performance compared with high was associated with smoking [odds ratio (OR) 3.94, 95% confidence interval (CI) 2.83-5.49], alcohol use (OR: 2.94, 95% CI: 2.34-3.68) and cannabis use (OR: 2.56, 95% CI: 1.89-3.48). Poor HL was also associated with each substance use (with ORs of 2.32, 1.85 and 1.29). HL was positively associated with academic performance (β = 1.04, 95% CI: 0.89-1.20). The associations between academic performance and substance use were only slightly attenuated after controlling for HL.

CONCLUSIONS

Academic performance and HL were both determinants of substance use, confirming their role in tackling the disparities in substance use. However, HL did not demonstrably mediate the association between academic performance and substance use. A wider set of factors needs to be tackled to address emerging social inequalities in adolescent substance use.

Size-dependent influence of NOx on the growth rates of organic aerosol particles

Atmospheric new-particle formation (NPF) affects climate by contributing to a large fraction of the cloud condensation nuclei (CCN). Highly oxygenated organic molecules (HOMs) drive the early particle growth and therefore substantially influence the survival of newly formed particles to CCN. Nitrogen oxide (NOx) is known to suppress the NPF driven by HOMs, but the underlying mechanism remains largely unclear. Here, we examine the response of particle growth to the changes of HOM formation caused by NOx. We show that NOx suppresses particle growth in general, but the suppression is rather nonuniform and size dependent, which can be quantitatively explained by the shifted HOM volatility after adding NOx. By illustrating how NOx affects the early growth of new particles, a critical step of CCN formation, our results help provide a refined assessment of the potential climatic effects caused by the diverse changes of NOx level in forest regions around the globe.

Ion-induced sulfuric acid-ammonia nucleation drives particle formation in coastal Antarctica

Formation of new aerosol particles from trace gases is a major source of cloud condensation nuclei (CCN) in the global atmosphere, with potentially large effects on cloud optical properties and Earth's radiative balance. Controlled laboratory experiments have resolved, in detail, the different nucleation pathways likely responsible for atmospheric new particle formation, yet very little is known from field studies about the molecular steps and compounds involved in different regions of the atmosphere. The scarcity of primary particle sources makes secondary aerosol formation particularly important in the Antarctic atmosphere. Here, we report on the observation of ion-induced nucleation of sulfuric acid and ammonia-a process experimentally investigated by the CERN CLOUD experiment-as a major source of secondary aerosol particles over coastal Antarctica. We further show that measured high sulfuric acid concentrations, exceeding 10⁷ molecules cm^-3, are sufficient to explain the observed new particle growth rates. Our findings show that ion-induced nucleation is the dominant particle formation mechanism, implying that galactic cosmic radiation plays a key role in new particle formation in the pristine Antarctic atmosphere.

Novel insights on new particle formation derived from a pan-european observing system

The formation of new atmospheric particles involves an initial step forming stable clusters less than a nanometre in size (<~1 nm), followed by growth into quasi-stable aerosol particles a few nanometres (~1–10 nm) and larger (>~10 nm). Although at times, the same species can be responsible for both processes, it is thought that more generally each step comprises differing chemical contributors. Here, we present a novel analysis of measurements from a unique multi-station ground-based observing system which reveals new insights into continental-scale patterns associated with new particle formation. Statistical cluster analysis of this unique 2-year multi-station dataset comprising size distribution and chemical composition reveals that across Europe, there are different major seasonal trends depending on geographical location, concomitant with diversity in nucleating species while it seems that the growth phase is dominated by organic aerosol formation. The diversity and seasonality of these events requires an advanced observing system to elucidate the key processes and species driving particle formation, along with detecting continental scale changes in aerosol formation into the future.

Production of neutral molecular clusters by controlled neutralization of mobility standards

Measuring aerosols and molecular clusters below the 3 nm size limit is essential to increase our understanding of new particle formation. Instruments for the detection of sub-3 nm aerosols and clusters exist and need to be carefully calibrated and characterized. So far calibrations and laboratory tests have been carried out using mainly electrically charged aerosols, as they are easier to handle experimentally. However, the charging state of the cluster is an important variable to take into account. Furthermore, instrument characterization performed with charged aerosols could be biased, preventing a correct interpretation of data when electrically neutral sub-3 nm aerosols are involved. This article presents the first steps to generate electrically neutral molecular clusters as standards for calibration. We show two methods: One based on the neutralization of well-known molecular clusters (mobility standards) by ions generated in a switchable aerosol neutralizer. The second is based on the controlled neutralization of mobility standards with mobility standards of opposite polarity in a recombination cell. We highlight the challenges of these two techniques and, where possible, point out solutions. In addition, we give an outlook on the next steps toward generating well-defined neutral molecular clusters with a known chemical composition and concentration. Published with license by American Association for Aerosol Research.

Atmospheric gas-to-particle conversion: why NPF events are observed in megacities?

In terms of the global aerosol particle number load, atmospheric new particle formation (NPF) dominates over primary emissions. The key for quantifying the importance of atmospheric NPF is to understand how gas-to-particle conversion (GTP) takes place at sizes below a few nanometers in particle diameter in different environments, and how this nano-GTP affects the survival of small clusters into larger sizes. The survival probability of growing clusters is tied closely to the competition between their growth and scavenging by pre-existing aerosol particles, and the key parameter in this respect is the ratio between the condensation sink (CS) and the cluster growth rate (GR). Here we define their ratio as a dimensionless survival parameter,P, asP= (CS/10⁻⁴s⁻¹)/(GR/nm h⁻¹). Theoretical arguments and observations in clean and moderately-polluted conditions indicate thatPneeds to be smaller than about 50 for a notable NPF to take place. However, the existing literature shows that in China, NPF occurs frequently in megacities such as in Beijing, Nanjing and Shanghai, and our analysis shows that the calculated values ofPare even larger than 200 in these cases. By combining direct observations and conceptual modelling, we explore the variability of the survival parameterPin different environments and probe the reasons for NPF occurrence under highly-polluted conditions.

New particle formation in the free troposphere: A question of chemistry and timing

New particle formation (NPF) is the source of over half of the atmosphere's cloud condensation nuclei, thus influencing cloud properties and Earth's energy balance. Unlike in the planetary boundary layer, few observations of NPF in the free troposphere exist. We provide observational evidence that at high altitudes, NPF occurs mainly through condensation of highly oxygenated molecules (HOMs), in addition to taking place through sulfuric acid-ammonia nucleation. Neutral nucleation is more than 10 times faster than ion-induced nucleation, and growth rates are size-dependent. NPF is restricted to a time window of 1 to 2 days after contact of the air masses with the planetary boundary layer; this is related to the time needed for oxidation of organic compounds to form HOMs. These findings require improved NPF parameterization in atmospheric models.

Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H₂SO₄) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H₂SO₄ in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H₂SO₄, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H₂SO₄ cluster distribution compared to binary (H₂SO₄-H₂O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H₂SO₄ monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

Acceleration of raindrop formation due to the tangling-clustering instability in a turbulent stratified atmosphere

Condensation of water vapor on active cloud condensation nuclei produces micron-size water droplets. To form rain, they must grow rapidly into at least 50- to 100-μm droplets. Observations show that this process takes only 15-20 min. The unexplained physical mechanism of such fast growth is crucial for understanding and modeling of rain and known as "condensation-coalescence bottleneck in rain formation." We show that the recently discovered phenomenon of the tangling clustering instability of small droplets in temperature-stratified turbulence [Phys. Fluids 25, 085104 (2013)] results in the formation of droplet clusters with drastically increased droplet number densities. The mechanism of the tangling clustering instability is much more effective than the previously considered by us the inertial clustering instability caused by the centrifugal effect of turbulent vortices. This is the reason of strong enhancement of the collision-coalescence rate inside the clusters. The mean-field theory of the droplet growth developed in this study can be useful for explanation of the observed fast growth of cloud droplets in warm clouds from the initial 1-μm-size droplets to 40- to 50-μm-size droplets within 15-20 min.

Anatomical regulation of ice nucleation and cavitation helps trees to survive freezing and drought stress

Water in the xylem, the water transport system of plants, is vulnerable to freezing and cavitation, i.e. to phase change from liquid to ice or gaseous phase. The former is a threat in cold and the latter in dry environmental conditions. Here we show that a small xylem conduit diameter, which has previously been shown to be associated with lower cavitation pressure thus making a plant more drought resistant, is also associated with a decrease in the temperature required for ice nucleation in the xylem. Thus the susceptibility of freezing and cavitation are linked together in the xylem of plants. We explain this linkage by the regulation of the sizes of the nuclei catalysing freezing and drought cavitation. Our results offer better understanding of the similarities of adaption of plants to cold and drought stress, and offer new insights into the ability of plants to adapt to the changing environment.

Heterogeneous nucleation in multi-component vapor on a partially wettable charged conducting particle. I. Formulation of general equations: electrical surface and line excess quantities

Thermodynamics is applied to formulate general equations for internal energies and grand potential for a system consisting of a dielectric liquid nucleus of a new phase on a charged insoluble conducting sphere within a uniform macroscopic one- or multicomponent mother phase. The currently available model for ion-induced nucleation assumes complete spherical symmetry of the system, implying that the seed ion is immediately surrounded by the condensing liquid from all sides. We take a step further and treat more realistic geometries, where a cap-shaped liquid cluster forms on the surface of the seed particle. To take into account spontaneous polarization of surface layer molecules we introduce the electrical surface and line excess quantities.

A new atmospherically relevant oxidant of sulphur dioxide

Atmospheric oxidation is a key phenomenon that connects atmospheric chemistry with globally challenging environmental issues, such as climate change, stratospheric ozone loss, acidification of soils and water, and health effects of air quality. Ozone, the hydroxyl radical and the nitrate radical are generally considered to be the dominant oxidants that initiate the removal of trace gases, including pollutants, from the atmosphere. Here we present atmospheric observations from a boreal forest region in Finland, supported by laboratory experiments and theoretical considerations, that allow us to identify another compound, probably a stabilized Criegee intermediate (a carbonyl oxide with two free-radical sites) or its derivative, which has a significant capacity to oxidize sulphur dioxide and potentially other trace gases. This compound probably enhances the reactivity of the atmosphere, particularly with regard to the production of sulphuric acid, and consequently atmospheric aerosol formation. Our findings suggest that this new atmospherically relevant oxidation route is important relative to oxidation by the hydroxyl radical, at least at moderate concentrations of that radical. We also find that the oxidation chemistry of this compound seems to be tightly linked to the presence of alkenes of biogenic origin.

MEGAPOLI: concept of multi-scale modelling of megacity impact on air quality and climate

Abstract. The EU FP7 Project MEGAPOLI: "Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation" (http://megapoli.info) brings together leading European research groups, state-of-the-art scientific tools and key players from non-European countries to investigate the interactions among megacities, air quality and climate. MEGAPOLI bridges the spatial and temporal scales that connect local emissions, air quality and weather with global atmospheric chemistry and climate. The suggested concept of multi-scale integrated modelling of megacity impact on air quality and climate and vice versa is discussed in the paper. It requires considering different spatial and temporal dimensions: time scales from seconds and hours (to understand the interaction mechanisms) up to years and decades (to consider the climate effects); spatial resolutions: with model down- and up-scaling from street- to global-scale; and two-way interactions between meteorological and chemical processes.

OH reactivity measurements within a boreal forest: evidence for unknown reactive emissions

Boreal forests emit large amounts of volatile organic compounds (VOCs) which react with the hydroxyl radical (OH) to influence regional ozone levels and form secondary organic aerosol. Using OH reactivity measurements within a boreal forest in Finland, we investigated the budget of reactive VOCs. OH reactivity was measured using the comparative reactivity method, whereas 30 individual VOCs were measured using proton transfer reaction mass spectrometry, thermal-desorption gas chromatography mass spectrometry, and liquid chromatography mass spectrometry, in August 2008. The measured OH reactivity ranged from below detection limit (3.5 s(-1)), to approximately 60 s(-1) in a single pollution event. The average OH reactivity was approximately 9 s(-1) and no diel variation was observed in the profiles. The measured OH sinks (approximately 30 species) accounted for only 50% of the total measured OH reactivity, implying unknown reactive VOCs within the forest. The five highest measured OH sinks were: monoterpenes (1 s(-1)), CO (0.7 s(-1)), isoprene (0.5 s(-1)), propanal and acetone (0.3 s(-1)), and methane (0.3 s(-1)). We suggest that models be constrained by direct OH reactivity measurements to accurately assess the impact of boreal forest emissions on regional atmospheric chemistry and climate.

Connection of sulfuric acid to atmospheric nucleation in boreal forest

Gas to particle conversion in the boundary layer occurs worldwide. Sulfuric acid is considered to be one of the key components in these new particle formation events. In this study we explore the connection between measured sulfuric acid and observed formation rate of both charged 2 nm as well as neutral clusters in a boreal forest environment A very short time delay of the order of ten minutes between these two parameters was detected. On average the event days were clearly associated with higher sulfuric acid concentrations and lower condensation sink (CS) values than the nonevent days. Although there was not a clear sharp boundary between the nucleation and no-nucleation days in sulfuric acid-CS plane, at our measurement site a typical threshold concentration of 3.10(5) molecules cm(-3) of sulfuric acid was needed to initiate the new particle formation. Two proposed nucleation mechanisms were tested. Our results are somewhat more in favor of activation type nucleation than of kinetic type nucleation, even though our data set is too limited to omit either of these two mechanisms. In line with earlier studies, the atmospheric nucleation seems to start from sizes very close to 2 nm.

Urban air pollution, and asthma and COPD hospital emergency room visits

BACKGROUND

There is little previous information of the effects of size fractioned particulate air pollution and source specific fine particles (PM(2.5); <2.5 microm) on asthma and chronic obstructive pulmonary disease (COPD) among children, adults and the elderly.

OBJECTIVES

To determine the effects of daily variation in levels of different particle size fractions and gaseous pollutants on asthma and COPD by age group.

METHODS

Levels of particulate air pollution, NO(2) and CO were measured from 1998 to 2004 at central outdoor monitoring sites in Helsinki, Finland. Associations between daily pollution levels and hospital emergency room visits were evaluated for asthma (ICD10: J45+J46) in children <15 years old, and for asthma and COPD (ICD10: J41+J44) in adults (15-64 years) and the elderly (>or=65 years).

RESULTS

Three to 5 day lagged increases in asthma visits were found among children in association with nucleation (<0.03 microm), Aitken (0.03-0.1 microm) and accumulation (0.1-0.29 microm) mode particles, gaseous pollutants and traffic related PM(2.5) (7.8% (95% CI 3.5 to 12.3) for 1.1 microg/m(3) increase in traffic related PM(2.5) at lag 4). Pooled asthma-COPD visits among the elderly were associated with lag 0 of PM(2.5), coarse particles, gaseous pollutants and long range transported and traffic related PM(2.5) (3.9% (95% CI 0.28 to 7.7) at lag 0). Only accumulation mode and coarse particles were associated with asthma and COPD among adults.

CONCLUSIONS

Among children, traffic related PM(2.5) had delayed effects, whereas among the elderly, several types of particles had effects that were more immediate. These findings suggest that the mechanisms of the respiratory effects of air pollution, and responsible pollutants, differ by age group.

Determination of isoprene and alpha-/beta-pinene oxidation products in boreal forest aerosols from Hyytiälä, Finland: diel variations and possible link with particle formation events

Biogenic volatile organic compounds (VOCs), such as isoprene and alpha-/beta-pinene, are photo-oxidized in the atmosphere to non-volatile species resulting in secondary organic aerosol (SOA). The goal of this study was to examine time trends and diel variations of oxidation products of isoprene and alpha-/beta-pinene in order to investigate whether they are linked with meteorological parameters or trace gases. Separate day-night aerosol samples (PM(1)) were collected in a Scots pine dominated forest in southern Finland during 28 July-11 August 2005 and analyzed with gas chromatography/mass spectrometry (GC/MS). In addition, inorganic trace gases (SO(2), CO, NO(x), and O(3)), meteorological parameters, and the particle number concentration were monitored. The median total concentration of terpenoic acids (i.e., pinic acid, norpinic acid, and two novel compounds, 3-hydroxyglutaric acid and 2-hydroxy-4-isopropyladipic acid) was 65 ng m(-3), while that of isoprene oxidation products (i.e., 2-methyltetrols and C(5) alkene triols) was 17.2 ng m(-3). The 2-methyltetrols exhibited day/night variations with maxima during day-time, while alpha-/beta-pinene oxidation products did not show any diel variation. The sampling period was marked by a relatively high condensation sink, caused by pre-existing aerosol particles, and no nucleation events. In general, the concentration trends of the SOA compounds reflected those of the inorganic trace gases, meteorological parameters, and condensation sink. Both the isoprene and alpha-/beta-pinene SOA products were strongly influenced by SO(2), which is consistent with earlier reports that acidity plays a role in SOA formation. The results support previous proposals that oxygenated VOCs contribute to particle growth processes above boreal forest.

Estimation of line tension and contact angle from heterogeneous nucleation experimental data

Using the classical nucleation theory corrected with line tension and experimental data of heterogeneous nucleation of n-nonane, n-propanol, and their mixture on silver particles of three different sizes, the authors were able to estimate the line tensions and the microscopic contact angles for the above mentioned systems. To do this they applied generalized Young's equation for the line tension and calculated the interfacial tensions using Li and Neumann's equation [Adv. Colloid Interface Sci. 39, 299 (1992)]. It has been found that, for both unary and binary systems, the line tension is negative and the resulting microscopic contact angle derived from experimental nucleation data is most of the time larger than the macroscopic one. This is in contrast to earlier studies where the influence of line tension has not been accounted for. The values of the three phase contact line tension obtained in this way are of the same order of magnitude as the estimations for other systems reported in literature. The line tension effect also decreases considerably the nucleation barrier.

Formation of Low-Temperature Cirrus from H2SO4/H2O Aerosol Droplets

We present experimental results obtained with a differential scanning calorimeter (DSC) that indicate the small ice particles in low-temperature cirrus clouds are not completely solid but rather coated with an unfrozen H2SO4/H2O overlayer. Our results provide a new look on the formation, development, and microphysical properties of low-temperature cirrus clouds.

Associations of traffic related air pollutants with hospitalisation for first acute myocardial infarction: the HEAPSS study

BACKGROUND

Acute myocardial infarction (AMI) is the leading cause of death attributed to cardiovascular diseases. An association between traffic related air pollution and AMI has been suggested, but the evidence is still limited.

OBJECTIVES

To evaluate in a multicentre study association between hospitalisation for first AMI and daily levels of traffic related air pollution.

METHODS

The authors collected data on first AMI hospitalisations in five European cities. AMI registers were available in Augsburg and Barcelona; hospital discharge registers (HDRs) were used in Helsinki, Rome and Stockholm. NO2, CO, PM10 (particles <10 microm), and O3 were measured at central monitoring sites. Particle number concentration (PNC), a proxy for ultrafine particles (<0.1 microm), was measured for a year in each centre, and then modelled retrospectively for the whole study period. Generalised additive models were used for statistical analyses. Age and 28 day fatality and season were considered as potential effect modifiers in the three HDR centres.

RESULTS

Nearly 27,000 cases of first AMI were recorded. There was a suggestion of an association of the same day CO and PNC levels with AMI: RR = 1.005 (95% CI 1.000 to 1.010) per 0.2 mg/m3 and RR = 1.005 (95% CI 0.996 to 1.015) per 10000 particles/cm3, respectively. However, associations were only observed in the three cities with HDR, where power for city-specific analyses was higher. The authors observed in these cities the most consistent associations among fatal cases aged <75 years: RR at 1 day lag for CO = 1.021 (95% CI 1.000 to 1.048) per 0.2 mg/m3, for PNC = 1.058 (95% CI 1.012 to 1.107) per 10000 particles/cm3, and for NO2 = 1.032 (95% CI 0.998 to 1.066) per 8 microg/m3. Effects of air pollution were more pronounced during the warm than the cold season.

CONCLUSIONS

The authors found support for the hypothesis that exposure to traffic related air pollution increases the risk of AMI. Most consistent associations were observed among fatal cases aged <75 years and in the warm season.

High Natural Aerosol Loading over Boreal Forests

Aerosols play a key role in the radiation balance of the atmosphere. Here, we present evidence that the European boreal region is a substantial source of both aerosol mass and aerosol number. The investigation supplies a straightforward relation between emissions of monoterpenes and gas-to-particle formation over regions substantially lacking in anthropogenic aerosol sources. Our results show that the forest provides an aerosol population of 1000 to 2000 particles of climatically active sizes per cubic centimeter during the late spring to early fall period. This has important implications for radiation budget estimates and relevancy for the evaluation of feedback loops believed to determine our future climate.

Homogeneous nucleation of n-nonane and n-propanol mixtures: A comparison of classical nucleation theory and experiments

The homogeneous nucleation rates for n-nonane-n-propanol vapor mixtures have been calculated as a function of vapor-phase activities at 230 K using the classical nucleation theory (CNT) with both rigorous and approximate kinetic prefactors and compared to previously reported experimental data. The predicted nucleation rates resemble qualitatively the experimental results for low n-nonane gas phase activity. On the high nonane activity side the theoretical nucleation rates are about three orders of magnitude lower than the experimental data when using the CNT with the approximate kinetics. The accurate kinetics improves the situation by reducing the difference between theory and experiments to two orders of magnitude. Besides the nucleation rate comparison and the experimental and predicted onset activities, the critical cluster composition is presented. The total number of molecules is approximated by CNT with reasonable accuracy. Overall, the classical nucleation theory with rigorous kinetic prefactor seems to perform better. The thermodynamic parameters needed to calculate the nucleation rates are revised extensively. Up-to-date estimates of liquid phase activities using universal functional activity coefficient Dortmund method are presented together with the experimental values of surface tensions obtained in the present study.

Fine particle number and mass concentration measurements in urban Indian households

Fine particle number concentration (D(p)>10 nm, cm(-3)), mass concentrations (approximation of PM(2.5), microg m(-3)) and indoor/outdoor number concentration ratio (I/O) measurements have been conducted for the first time in 11 urban households in India, 2002. The results indicate remarkable high indoor number and mass concentrations and I/O number concentration ratios caused by cooking. Besides cooking stoves that used liquefied petroleum gas (LPG) or kerosene as the main fuel, high indoor concentrations can be explained by poor ventilation systems. Particle number concentrations of more than 300,000 cm(-3) and mass concentrations of more than 1000 microg m(-3) were detected in some cases. When the number and mass concentrations during cooking times were statistically compared, a correlation coefficient r>0.50 was observed in 63% of the households. Some households used other fuels like wood and dung cakes along with the main fuel, but also other living activities influenced the concentrations. In some areas, outdoor combustion processes had a negative impact on indoor air quality. The maximum concentrations observed in most cases were due to indoor combustion sources. Reduction of exposure risk and health effects caused by poor indoor air in urban Indian households is possible by improving indoor ventilation and reducing penetration of outdoor particles.