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Background: Rapid urbanisation and population growth in sub-Saharan Africa has increased the incidence of asthma in children and adolescents. One major barrier to achieving good asthma control in these adolescents is obtaining a clinical diagnosis. To date, there are scant data on prevalence and severity of asthma in undiagnosed yet symptomatic adolescents. We therefore aimed to assess symptom prevalence and severity, the effect of symptoms on daily life, and objective evidence of asthma in young adolescents from sub-Saharan Africa with and without a clinical diagnosis of asthma by spirometry and fractional exhaled nitric oxide (FeNO)., Methods: We designed a two-phase, multi-country, school-based, cross-sectional study to assess symptom prevalence and severity in sub-Saharan African adolescents. In phase 1 we surveyed young adolescents aged 12-14 years who were attending selected primary and secondary schools in Blantyre in Malawi, Durban in South Africa, Harare in Zimbabwe, Kampala in Uganda, Kumasi in Ghana, and Lagos in Nigeria. The adolescents were screened for asthma symptoms using the International Study of Asthma and Allergies in Children (ISAAC) questionnaire. Then, after opt-in consent, symptomatic adolescents were invited to complete a detailed survey on asthma severity, treatment, and exposure to environmental risk factors for phase 2. Adolescents performed the European Respiratory Society's diagnostic tests for childhood asthma. A positive asthma test was classified as a forced expiratory volume in 1 sec (FEV 1 ) predicted under 80%, a FEV 1 under the lower limits of normal, or FEV 1 divided by forced vital capacity (FEV 1 /FVC) under the lower limits of normal; positive bronchodilator responsiveness or reversibility was defined as either an increase in absolute FEV 1 of 12% or more, or an increase of 200 mL or more, or both, after 400 μg of salbutamol (shortacting β2 agonist) administered via a metered-dose inhaler and spacer, or FeNO of 25 parts per billion or higher, or any combination of these. The study was registered with ClinicalTrials.gov (NCT03990402) and is complete., Findings: Between Nov 1, 2018, and Nov 1, 2021, we recruited 149 schools from six regions in six sub-Saharan countries to participate in the study. We administered phase 1 asthma questionnaires from Jan 20, 2019 to Nov 11, 2021, and from 27 407 adolescents who were screened, we obtained data for 27 272 (99·5%). Overall, 14 918 (54·7%) adolescents were female and 12 354 (45·3%) adolescents were male, and the mean age was 13 years (IQR 12-13); nearly all recruited adolescents were of black African ethnicity (26 821 [98·3%] of 27 272). In phase 1, a total of 3236 (11·9% [95% CI 11·5-12·3]) reported wheeze in the past 12 months, and 644 (19·9%) of 3236 had a formal clinical diagnosis of asthma. The prevalence of adolescents with asthma symptoms ranged from 23·8% in Durban, South Africa to 4·2% Blantyre, Malawi. Using ISAAC criteria, severe asthma symptoms were reported by 2146 (66·3%) of 3236 adolescents, the majority of whom (1672 [77·9%] of 2146) had no diagnosis of asthma by a clinician. Between July 16, 2019, and Nov 26, 2021, we administered the phase 2 questionnaire to the 1654 adolescents who had asthma symptoms in phase 1 and consented to proceed to the second phase. In the phase 2 cohort, 959 (58·0%) were female and 695 (42·0%) were male, and the mean age was 13 years (IQR 12-14). One or more diagnostic tests for asthma were obtained in 1546 (93·5%) of 1654 participants. One or more positive asthma tests were found in 374 (48·8%) of 767 undiagnosed adolescents with severe symptoms, and 176 (42·4%) of 415 of undiagnosed adolescents with mild-to-moderate symptoms. Of the 392 adolescents in phase 2 with clinician-diagnosed asthma, 294 (75·0%) reported severe asthma symptoms, with 94 (32·0%) of those with severe symptoms not using any asthma medication. In general, findings in both phases 1 and 2 were consistent across sub-Saharan African countries., Interpretation: A large proportion of adolescents in sub-Saharan Africa with symptoms of severe asthma do not have a formal diagnosis of asthma and are therefore not receiving appropriate asthma therapy. To improve the poor state of asthma control in sub-Saharan Africa, potential solutions such as educational programmes, better diagnosis, and treatment and screening in schools should be considered., Funding: UK National Institute for Health and Care Research and UK Medical Research Council., Competing Interests: Declaration of interests OOA is an unpaid convener for Lung Health Improvement Initiative. CJG is an investigator in the Genes and Health Programme with funds from Alnylam Pharmaceuticals, Genomics, and a Life Sciences Industry Consortium of AstraZeneca, Bristol-Myers Squibb, GSK Research and Development, Maze Therapeutics, Merck Sharp & Dohme, Novo Nordisk, Pfizer, and Takeda Development Centre Americas. JG is a National Institute for Health and Care Research Senior Investigator, and reports research grants from OM Pharma and Marinomed, honoraria from AstraZeneca, payment from OM Pharma as an Advisory Board member, gift of asthma equipment from Omron, donation of Investigational Medicinal Product from Marinomed and OM Pharma, and was commissioned by Hodge Jones & Allen Solicitors to provide medical evidence related to the inquest on an asthma death. All other authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.)

Background: Air pollution is the second largest risk to health in Africa, and children with asthma are particularly susceptible to its effects. Yet, there is a scarcity of air pollution exposure data from cities in sub-Saharan Africa. We aimed to identify potential exposure reduction strategies for school children with asthma living in urban areas in sub-Saharan Africa., Methods: This personal exposure study was part of the Achieving Control of Asthma in Children in Africa (ACACIA) project. Personal exposure to particulate matter (PM) was monitored in school children in six cities in sub-Saharan Africa (Blantyre, Malawi; Durban, South Africa; Harare, Zimbabwe; Kumasi, Ghana; Lagos, Nigeria; and Moshi, Tanzania). Participants were selected if they were aged 12-16 years and had symptoms of asthma. Monitoring was conducted between June 21, and Nov 26, 2021, from Monday morning (approximately 1000 h) to Friday morning (approximately 1000 h), by use of a bespoke backpack with a small air pollution monitoring unit with an inbuilt Global Positioning System (GPS) data logger. Children filled in a questionnaire detailing potential sources of air pollution during monitoring and exposures were tagged into three different microenvironments (school, commute, and home) with GPS coordinates. Mixed-effects models were used to identify the most important determinants of children's PM 2·5 (PM <2·5 μm in diameter) exposure., Findings: 330 children were recruited across 43 schools; of these, 297 had valid monitoring data, and 1109 days of valid data were analysed. Only 227 (20%) of 1109 days monitored were lower than the current WHO 24 h PM 2·5 exposure health guideline of 15 μg/m 3 . Children in Blantyre had the highest PM 2·5 exposure (median 41·8 μg/m 3 ), whereas children in Durban (16·0 μg/m 3 ) and Kumasi (17·9 μg/m 3 ) recorded the lowest exposures. Children had significantly higher PM 2·5 exposures at school than at home in Kumasi (median 19·6 μg/m 3 vs 14·2 μg/m 3 ), Lagos (32·0 μg/m 3 vs 18·0 μg/m 3 ), and Moshi (33·1 μg/m 3 vs 23·6 μg/m 3 ), while children in the other three cities monitored had significantly higher PM 2·5 exposures at home and while commuting than at school (median 48·0 μg/m 3 and 43·2 μg/m 3 vs 32·3 μg/m 3 in Blantyre, 20·9 μg/m 3 and 16·3 μg/m 3 vs 11·9 μg/m 3 in Durban, and 22·7 μg/m 3 and 25·4 μg/m 3 vs 16·4 μg/m 3 in Harare). The mixed-effects model highlighted the following determinants for higher PM 2·5 exposure: presence of smokers at home (23·0% higher exposure, 95% CI 10·8-36·4), use of coal or wood for cooking (27·1%, 3·9-56·3), and kerosene lamps for lighting (30·2%, 9·1-55·2). By contrast, 37·2% (95% CI 22·9-48·2) lower PM 2·5 exposures were found for children who went to schools with paved grounds compared with those whose school grounds were covered with loose dirt., Interpretation: Our study suggests that the most effective changes to reduce PM 2·5 exposures in these cities would be to provide paving in school grounds, increase the use of clean fuel for cooking and light in homes, and discourage smoking within homes. The most efficient way to improve air quality in these cities would require tailored interventions to prioritise different exposure-reduction policies in different cities., Funding: UK National Institute for Health and Care Research., Competing Interests: Declaration of interests JG reports grants from OM Pharma, Mariomed, and Biotech; advisory board membership on OM Pharma, GlaxoSmithKline, and AstraZeneca; payment from Hodge Jones & Allen Solicitors for medical advice to a coroner's inquest into a child who died from asthma. All other authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Asthma is the most common chronic respiratory disease among school-going adolescents worldwide. However, the burden of severe asthma is highest in Sub-Saharan Africa. This study aimed to explore teachers' perceptions of asthma care across six African countries. We conducted focus group discussions (FGDs) using a semi-structured interview guide. Interviews were audio-recorded, transcribed verbatim and analysed thematically. FGDs were conducted in Kumasi(Ghana), Blantyre (Malawi), Lagos (Nigeria), Durban (South Africa), Kampala (Uganda), and Harare (Zimbabwe) between 01 November 2020 and 30 June 2021. We identified two key themes related to asthma care; barriers to asthma care and suggestions to improve the care of adolescents with asthma. Barriers reported by teachers included a lack of knowledge and skills among themselves, adolescents, and caregivers. In addition, some traditional beliefs of teachers on asthma exacerbated challenges with asthma care in schools. Regarding suggestions, most teachers identified a need for all-inclusive asthma training programmes for teachers, adolescents and caregivers, focusing on acute episodes and mitigating triggers. Utilising teachers with personal experiences with asthma to advocate and support these initiatives was suggested. Further suggestions included the need for annual screening to enable early identification of adolescents with asthma and clarify restrictions on teachers administering asthma medications. Teachers across African schools identify multiple barriers to asthma care. Structured school education programs and annual asthma screening are key to addressing some barriers to care., (© 2023. Springer Nature Limited.)

Objectives: This study identifies barriers and provides recommendations to improve asthma care in children across sub-Saharan Africa, where qualitative data is lacking despite high rates., Design: One of the aims of our National Institute for Health Research global health research group 'Achieving Control of Asthma in Children in Africa' was to use qualitative thematic analysis of transcribed audio recordings from focus group discussions (FGDs) to describe barriers to achieving good asthma control., Setting: Schools in Blantyre (Malawi), Lagos (Nigeria), Durban (South Africa), Kampala (Uganda) and Harare (Zimbabwe)., Participants: Children (n=136), 12-14 years with either asthma symptoms or a diagnosis and their caregivers participated in 39 FGDs. All were recruited using asthma control questions from the Global Asthma Network survey., Results: There were four key themes identified: (1) Poor understanding, (2) difficulties experienced with being diagnosed, (3) challenges with caring for children experiencing an acute asthma episode and (4) suboptimal uptake and use of prescribed medicines. An inadequate understanding of environmental triggers, a hesitancy in using metred dose inhalers and a preference for oral and alternate medications were identified as barriers. In addition, limited access to healthcare with delays in diagnosis and an inability to cope with expected lifestyle changes was reported. Based on these findings, we recommend tailored education to promote access to and acceptance of metred dose inhalers, including advocating for access to a single therapeutic, preventative and treatment option. Furthermore, healthcare systems should have simpler diagnostic pathways and easier emergency access for asthma., Conclusions: In a continent with rapidly increasing levels of poorly controlled asthma, we identified multiple barriers to achieving good asthma control along the trajectory of care. Exploration of these barriers reveals several generalisable recommendations that should modify asthma care plans and potentially transform asthma care in Africa., Trial Registration Number: 269211., Competing Interests: Competing interests: The author(s) declare that they have no financial or personal relationship(s) that may have inappropriately influenced them in writing this article. The funder did not influence the results and compiling of the manuscript. JG reports personal fees from GSK, personal fees from Novartis, personal fees and a grant to QMUL from OM Pharma, personal fees and payment to QMUL from AstraZeneca, personal fees from Omron, outside the submitted work, and is supported by an NIHR Senior Investigator Award. RM reports consultancy and advisory board membership from AstraZeneca, Boehringer and Organon., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY. Published by BMJ.)

Background: Children with poorly controlled asthma have higher rates of unplanned healthcare use and school absences, as well as lower rates of medication adherence and knowledge. They also feel less comfortable using their medication at school, due to social fears and bullying. In this study, this was addressed through two school-based self-management interventions piloted to determine which one to use in a full trial., Methods: We sought to assess the feasibility and acceptability of two school-based self-management intervention aimed at improving asthma control. Schools in London were randomised to (i) a theatre workshop for the whole year group aimed at raising awareness of asthma in schools, followed by self-management workshops for children (full intervention), (ii) theatre workshop alone (theatre only), or (iii) usual care (controls). Opt-out consent was obtained from parents. The study was a cluster randomised pilot trial, using London schools as the unit of allocation. Our primary aim was to assess the feasibility of delivering a self-management intervention in schools aimed at improving the asthma control test (ACT) score at 6 months. Secondary outcomes included acceptability of the school-based interventions, suitability of the theatre intervention and the full intervention with the self-management workshops, and generation of randomised data to inform future power calculations. Data were analysed by generalised mixed-effect models., Results: The recruitment strategy for this trial was effective. Five schools were randomised to full intervention (189 children), four to theatre only (103 children), and six to controls (83 children). Asthma control test (ACT) score at baseline and 6 months was obtained from 178/358 participating children. Compared with the controls, there were no large differences found in ACT score with the full intervention; knowledge and perception of asthma improved though. GP and hospital visits increased in the full intervention group. Compared with controls, ACT score was unchanged in the theatre only group., Conclusion: The asthma self-management intervention trial in schools is feasible and acceptable. The full intervention consisting of both theatre and self-management workshop for asthmatics tended to be better suited to improve outcomes than the theatre intervention on its own. This full intervention should be the one carried forward into a main trial if funding for further research was sought. Further work is needed to understand why there was evidence that unscheduled visits to healthcare professionals increased with the full intervention., Trial Registration: The study was registered on the clinical trials database on 14th May 2018 (ID NCT03536416 )., (© 2022. The Author(s).)

Background: Asthma control in adolescents is low with half of the young people in a London study identified as having suboptimal control when measured using the Asthma Control Test. Control of asthma symptoms can be improved by addressing barriers to good self-management, such as poor understanding of asthma and adherence to medication. The aim of this study was therefore to develop the My Asthma in School (MAIS) intervention for the improvement of asthma control and self-management in adolescents and to test its initial feasibility. The intervention intended to combine a strong focus on theory with a design specifically aimed to engage adolescents., Methods: The intervention development was based on previous qualitative and quantitative findings, and on guidelines from the Medical Research Council for the development of complex interventions. The COM-B (Capability, Opportunity, Motivation-Behaviour) model was applied to inform the design of intervention elements. Behavioural targets were identified from existing barriers to good asthma self-management and were then used to guide the development of engaging intervention elements, which were described using the Behavioural Change Technique (BCT) Taxonomy version 1. Adolescents were involved throughout this process. The MAIS intervention was tested in a feasibility phase in London secondary schools with adolescents aged between 11 and 13., Results: The complex school-based MAIS intervention comprised a first school visit from a theatre group, who conducted a workshop with all year 7-8 students and addressed peer understanding and attitudes to asthma. The second visit included four self-management workshops for adolescents with asthma, including games, short-films and role play activities. Forty different types of techniques to change behaviour were applied, totalling 163 instances of BCT use across intervention elements, addressing all areas of capability, opportunity and motivation. In this initial feasibility study, 1814 adolescents with and without asthma from nine schools received the theatre intervention visit; 23 adolescents with asthma from one of the schools attended the workshop visit. The intervention was found acceptable and engaging, and 91.4% of participants agreed that the workshops changed how they think or feel about asthma., Conclusion: This study demonstrates development and initial feasibility of a complex theory-based intervention, and how it can combine engaging media and interactive elements, to achieve a multi-directional approach to behavioural change. However more work is needed to assess the feasibility of trial processes, including recruitment and delivery format of the workshops., Competing Interests: Competing interestsThe authors declare that they have no competing interests., (© The Author(s) 2020.)

Introduction: Little is known about asthma control in the rising number of African children who suffer from this condition. The Achieving Control of Asthma in Children in Africa (ACACIA) study is an observational study collecting evidence about paediatric asthma in urban areas of Ghana, Malawi, Nigeria, South Africa, Uganda and Zimbabwe. The primary objectives are: (1) to identify 3000 children aged between 12 years and 14 years with asthma symptoms; and (2) to assess their asthma control, current treatment, knowledge of and attitudes to asthma and barriers to achieving good control. Secondary objective is to develop interventions addressing identified barriers to good symptom control., Methods and Analysis: Each centre will undertake screening to identify 500 school children with asthma symptoms using questions from the Global Asthma Network's questionnaire. Children identified to have asthma symptoms will fill in a digital survey, including: Asthma Control Test, questions on medication usage and adherence, medical care, the Brief-Illness Perception questionnaire and environmental factors. Exhaled nitric oxide testing and prebronchodilator and postbronchodilator spirometry will be performed. A subgroup of children will participate in focus group discussions. Results will be analysed using descriptive statistics and comparative analysis. Informed by these results, we will assess the feasibility of potential interventions, including the adaption of a UK-based theatre performance about asthma attitudes and digital solutions to improve asthma management., Ethics and Dissemination: The ACACIA study has been reviewed by the Queen Mary University of London Ethics of Research Committee in the UK. All African centres have received local ethical approval for this study. Study results will be published in academic journals and at conferences. Study outputs will be communicated to the public via newsfeeds on the ACACIA website and Twitter, and through news media outlets and other local dissemination., Trial Registration Number: 269211., Competing Interests: Competing interests: JG reports personal fees from GSK, personal fees from Vifor Pharmaceuticals, personal fees from Novartis, personal fees from BV Pharma, personal fees from AstraZeneca, outside the submitted work., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ.)

Introduction: Asthma-related morbidity and mortality in the UK is higher than elsewhere in Europe. Although the reasons for this are largely unclear, one explanation could be a higher prevalence of poorly controlled asthma in the UK. Findings from our earlier study found that, in a sample of 766 children with asthma, 45.7% had poorly controlled asthma. Our earlier study also showed that adherence to inhaled corticosteroids was low. Subsequent focus groups identified concerns regarding embarrassment and bullying as barriers to adherence, as well as forgetfulness and incorrect medication beliefs. Following this, a school-based self-management intervention has been developed, aimed to improve asthma control and self-management behaviours., Methods and Analysis: The theory-based cluster randomised controlled trial tests an intervention comprising two components: (1) a theatre workshop for all children in years 7 and 8, and (2) self-management workshops for children with asthma. The COM-B model was used to guide the development of the intervention. Questionnaire data will be collected in schools at baseline, immediately post intervention, and 3, 6 and 12 months post intervention. The data collected at 6 months will measure the effect of the intervention against the baseline data. The primary outcome will be asthma control, measured using the Asthma Control Test. All the data will be analysed quantitatively using generalised linear and non-linear mixed effects models., Ethics and Dissemination: Ethical approval was obtained by the Queen Mary University of London Ethics Committee on 12 April 2018. Regular meetings will be held with key patient and public stakeholders to plan the key messages from this research. Key messages from the study will also be tweeted via the project twitter account (@SchoolsAsthma). The findings of the study will be submitted for presentation at conferences, as well as written into a manuscript., Trial Registration Number: MGU0400., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: The asthma control test (ACT) is a validated tool for assessing control in asthmatic children aged 12 years and older. Using the ACT, we sought to assess asthma control and knowledge in London secondary school children., Methods: Secondary schools in London, UK, participated in this study. Children with doctor-diagnosed asthma were invited to complete an online questionnaire that included the ACT and questions about asthma. Suboptimal asthma control was defined as an ACT score of ≤ 19 out of a maximum score of 25. Data are summarised as median and interquartile range (IQR), and were analysed by either Mann-Whitney test, or chi-square test. A p value of < 0.05 was considered significant., Results: A total of 799 children completed the questionnaire; 689 (86.2%) were included for analysis. Suboptimal asthma control was reported by 49.6% of students. Over a third (42.4%) of students prescribed a short-acting β2-agonist inhaler felt uncomfortable using it at school, and 29.2% (n = 173) reported not using this inhaler when wheezy. 56.4% (n = 220) of those with regular inhaled corticosteroids did not take them as prescribed, and 41.7% did not know what this inhaler was for. Suboptimal control was associated with a greater proportion of students reporting that they were 'somewhat', 'hardly' or 'not at all' comfortable using inhalers at school (52.7% vs 29.1%, p < 0.01) and outside school (22.8% vs. 14.8%, p < 0.01)., Conclusions: Suboptimal asthma control and poor asthma knowledge are common in London schoolchildren.

An increasing number of epidemiological studies suggest that adverse health effects of air pollution may be related to particulate matter (PM) composition, particularly trace metals. However, we lack comprehensive data on the spatial distribution of these elements. We measured PM2.5 and PM10 in twenty study areas across Europe in three seasonal two-week periods over a year using Harvard impactors and standardized protocols. In each area, we selected street (ST), urban (UB) and regional background (RB) sites (totaling 20) to characterize local spatial variability. Elemental composition was determined by energy-dispersive X-ray fluorescence analysis of all PM2.5 and PM10 filters. We selected a priori eight (Cu, Fe, K, Ni, S, Si, V, Zn) well-detected elements of health interest, which also roughly represented different sources including traffic, industry, ports, and wood burning. PM elemental composition varied greatly across Europe, indicating different regional influences. Average street to urban background ratios ranged from 0.90 (V) to 1.60 (Cu) for PM2.5 and from 0.93 (V) to 2.28 (Cu) for PM10. Our selected PM elements were variably correlated with the main pollutants (PM2.5, PM10, PM2.5 absorbance, NO2 and NOx) across Europe: in general, Cu and Fe in all size fractions were highly correlated (Pearson correlations above 0.75); Si and Zn in the coarse fractions were modestly correlated (between 0.5 and 0.75); and the remaining elements in the various size fractions had lower correlations (around 0.5 or below). This variability in correlation demonstrated the distinctly different spatial distributions of most of the elements. Variability of PM10&#95;Cu and Fe was mostly due to within-study area differences (67% and 64% of overall variance, respectively) versus between-study area and exceeded that of most other traffic-related pollutants, including NO2 and soot, signaling the importance of non-tailpipe (e.g., brake wear) emissions in PM., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Patient education is an essential part in the treatment of coronary heart disease in medical rehabilitation. In the German-speaking area, no standardized and evaluated patient education program for coronary heart disease is available so far. In this paper, we demonstrate the development of a quality assured patient education program based on a health-education program of the German statutory pension insurance scheme., Methods: In a multi-level approach, an existing program was modified concerning treatment evidence, practical guidelines, theories of health and illness behavior and quality criteria for patient education as well as clinical experience and thereafter manualized. In a formative evaluation, feasibility and patient acceptance of this modified program were assessed using evaluation questionnaires of patients and trainers. Afterwards, effects of the patient education program as compared to a traditional education program were assessed on a short-term (at discharge), medium-term (6-month follow-up) and long-term (12-month follow-up) basis in a multicenter quasi-experimental control group study of patients with coronary heart disease (n=434)., Results: Results of the formative evaluation demonstrate an overall good acceptance and a good feasibility of the manualized program. Short-term results show a significant small treatment effect in the primary outcome variable patients' knowledge (p=0.001, η2 =0.028). Furthermore, small effects were also observed among some secondary outcomes, such as attitude towards medication, planning of physical activity, psychological quality of life and satisfaction with the education program., Conclusion: A standardized education program for patients with coronary heart disease has been developed in a systematic process based on established quality standards. Depending on the outstanding medium and long-term effects, the program may be recommended for general use in medical rehabilitation. The manual provides the prerequisites allowing for a successful transfer into clinical practice., (© Georg Thieme Verlag KG Stuttgart · New York.)

Land Use Regression (LUR) models have been used to describe and model spatial variability of annual mean concentrations of traffic related pollutants such as nitrogen dioxide (NO2), nitrogen oxides (NOx) and particulate matter (PM). No models have yet been published of elemental composition. As part of the ESCAPE project, we measured the elemental composition in both the PM10 and PM2.5 fraction sizes at 20 sites in each of 20 study areas across Europe. LUR models for eight a priori selected elements (copper (Cu), iron (Fe), potassium (K), nickel (Ni), sulfur (S), silicon (Si), vanadium (V), and zinc (Zn)) were developed. Good models were developed for Cu, Fe, and Zn in both fractions (PM10 and PM2.5) explaining on average between 67 and 79% of the concentration variance (R(2)) with a large variability between areas. Traffic variables were the dominant predictors, reflecting nontailpipe emissions. Models for V and S in the PM10 and PM2.5 fractions and Si, Ni, and K in the PM10 fraction performed moderately with R(2) ranging from 50 to 61%. Si, NI, and K models for PM2.5 performed poorest with R(2) under 50%. The LUR models are used to estimate exposures to elemental composition in the health studies involved in ESCAPE.

Land use regression models (LUR) frequently use leave-one-out-cross-validation (LOOCV) to assess model fit, but recent studies suggested that this may overestimate predictive ability in independent data sets. Our aim was to evaluate LUR models for nitrogen dioxide (NO2) and particulate matter (PM) components exploiting the high correlation between concentrations of PM metrics and NO2. LUR models have been developed for NO2, PM2.5 absorbance, and copper (Cu) in PM10 based on 20 sites in each of the 20 study areas of the ESCAPE project. Models were evaluated with LOOCV and "hold-out evaluation (HEV)" using the correlation of predicted NO2 or PM concentrations with measured NO2 concentrations at the 20 additional NO2 sites in each area. For NO2, PM2.5 absorbance and PM10 Cu, the median LOOCV R(2)s were 0.83, 0.81, and 0.76 whereas the median HEV R(2) were 0.52, 0.44, and 0.40. There was a positive association between the LOOCV R(2) and HEV R(2) for PM2.5 absorbance and PM10 Cu. Our results confirm that the predictive ability of LUR models based on relatively small training sets is overestimated by the LOOCV R(2)s. Nevertheless, in most areas LUR models still explained a substantial fraction of the variation of concentrations measured at independent sites.