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BACKGROUND: Changes in land use and climate change have been reported to reduce biodiversity of both the environment and human microbiota. These reductions in biodiversity may lead to inadequate and unbalanced stimulation of immunoregulatory circuits and, ultimately, to clinical diseases, such as asthma and allergies. OBJECTIVE: We summarized available empirical evidence on the role of inner (gut, skin, and airways) and outer (air, soil, natural waters, plants, and animals) layers of biodiversity in the development of asthma, wheezing, and allergic sensitization. METHODS: We conducted a systematic search in SciVerse Scopus, PubMed MEDLINE, and Web of Science up to 5 March 2024 to identify relevant human studies assessing the relationships between inner and outer layers of biodiversity and the risk of asthma, wheezing, or allergic sensitization. The protocol was registered in PROSPERO (CRD42022381725). RESULTS: A total of 2,419 studies were screened and, after exclusions and a full-text review of 447 studies, 82 studies were included in the comprehensive, final review. Twenty-nine studies reported a protective effect of outer layer biodiversity in the development of asthma, wheezing, or allergic sensitization. There were also 16 studies suggesting an effect of outer layer biodiversity on increasing asthma, wheezing, or allergic sensitization. However, there was no clear evidence on the role of inner layer biodiversity in the development of asthma, wheezing, and allergic sensitization (13 studies reported a protective effect and 15 reported evidence of an increased risk). CONCLUSIONS: Based on the reviewed literature, a future systematic review could focus more specifically on outer layer biodiversity and asthma. It is unlikely that association with inner layer biodiversity would have enough evidence for systematic review. Based on this comprehensive review, there is a need for population-based longitudinal studies to identify critical periods of exposure in the life course into adulthood and to better understand mechanisms linking environmental exposures and changes in microbiome composition, diversity, and/or function to development of asthma and allergic sensitization. [ABSTRACT FROM AUTHOR]

We applied data from a population-based prospective study, the Espoo Cohort Study (n  = 2,568), to identify the potential susceptibility of persons with asthma to respiratory tract infections (RTIs). Information on the occurrence of asthma and both upper respiratory tract infections (URTIs) and lower respiratory tract infections (LRTIs) was collected with a questionnaire at baseline and at the 6-year and 20-year follow-up studies, and from the Finnish national health registries. We estimated age- and sex-specific incidence rate differences (IRDs) and incidence rate ratios (IRRs) by applying negative binomial regression. Meta-regression was used to summarize the age-specific IRRs from childhood to 27 years of age. Individuals with asthma at any age during the follow-up period had increased risks of both URTIs (adjusted IRD = 72.6 (95% confidence interval (CI): 50.6, 94.7) per 100 person-years; adjusted IRR = 1.27 (95% CI: 1.20, 1.35)) and LRTIs (adjusted IRD = 25.5 (95% CI: 17.9, 33.1); adjusted IRR = 2.87 (95% CI: 2.33, 3.53)) from childhood to young adulthood. In young adulthood, the association between asthma and URTIs was stronger in women than in men, while such an association was not detected for LRTIs. This analysis provides strong evidence that persons with asthma experience more RTIs from preschool age to young adulthood than do those without asthma. Thus, they constitute a susceptible population for RTIs. Women with asthma are at especially high risk. [ABSTRACT FROM AUTHOR]

BACKGROUND: Despite the recent developments in physically and chemically based analysis of atmospheric particles, no models exist for resolving the spatial variability of pollen concentration at urban scale. OBJECTIVE: We developed a land use regression (LUR) approach for predicting spatial fine-scale allergenic pollen concentrations in the Helsinki metropolitan area, Finland, and evaluated the performance of the models against available empirical data. METHODS: We used grass pollen data monitored at 16 sites in an urban area during the peak pollen season and geospatial environmental data. The main statistical method was generalized linear model (GLM). RESULTS: GLM-based LURs explained 79% of the spatial variation in the grass pollen data based on all samples, and 47% of the variation when samples from two sites with very high concentrations were excluded. In model evaluation, prediction errors ranged from 6% to 26% of the observed range of grass pollen concentrations. Our findings support the use of geospatial data--based statistical models to predict the spatial variation of allergenic grass pollen concentrations at intra-urban scales. A remote sensing-based vegetation index was the strongest predictor of pollen concentrations for exposure assessments at local scales. CONCLUSION: The LUR approach provides new opportunities to estimate the relations between environmental determinants and allergenic pollen concentration in human-modified environments at fine spatial scales. This approach could potentially be applied to estimate retrospectively pollen concentrations to be used for long-term exposure assessments. http://dx.doi.org/10.1289/ehp.1509761, Introduction Asthma is globally the most common chronic disease in children, and it affects approximately 7.7% of the working-age population in the United States (Henneberger et al. 2011) and 3-9% [...]

Abstract Background There is little information on potential differences in animal exposure between Finland and Russia and particularly on the effects of animal exposure on asthma among Russian children. The aim of the study was to compare the pet and farm animal exposures and to assess the relations of pre- and postnatal animal exposures to the occurrence of allergic asthma in Finnish and Russian school children. Methods We conducted a population-based cross-sectional study in neighbour towns on either side of the Finnish-Russian border; Imatra in Finland and Svetogorsk in Russia. The study population consisted of 512 Finnish and 581 Russian school children aged 7–16 years (response rate 79%). Multivariate logistic regression analysis was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI) related to each exposure. Results Current indoor exposure to pets was more frequent among school children in Svetogorsk than in Imatra (67.5% vs. 56.0%, P < 0.001). Finnish children were exposed more frequently to dogs, whereas Russian children to cats during childhood and to farm animals during pregnancy and infancy. The risk of self-reported allergic asthma was inversely related to indoor dog keeping ever in Finland (adjusted OR 0.35, 95% CI 0.13, 0.95), whereas in Russia the risk of allergic asthma was increased in relation to combined indoor cat exposure during infancy and currently (4.56, 1.10, 18.91). The risk of asthma was elevated in relation to contact to farm animals during pregnancy (Finland: 1.95, 0.69, 5.50; Russia: 1.90, 0.70, 5.17) and early life (Finland: 2.05, 0.78, 5.40; Russia: 1.21, 0.39, 3.73). Conclusion Exposure to pets and farm animals during childhood differed significantly between Finland and Russia. Our study provides evidence that early-life exposure to cats increases the risk of asthma whereas exposure to dogs is protective. Our findings suggest that intermittent fetal and early-life exposure to farm animals increases the risk of allergic asthma in urban children visiting farms.

Background: According to our systematic literature review, no previous study has assessed potential effects of regular exercise on asthma control among young adults. We hypothesized that regular exercise improves asthma control among young adults. Methods: We studied 162 subjects with current asthma recruited from a population-based cohort study of 1,623 young adults 20-27 years of age. Asthma control was assessed by the occurrence of asthma-related symptoms, including wheezing, shortness of breath, cough, and phlegm production, during the past 12 months. Asthma symptom score was calculated based on reported frequencies of these symptoms (range: 0-12). Exercise was assessed as hours/week. Results: In Poisson regression, adjusting for gender, age, smoking, environmental tobacco smoke exposure, and education, the asthma symptom score reduced by 0.09 points per 1 hour of exercise/week (95% CI: 0.00 to 0.17). Applying the “Low exercise” quartile as the reference, “Medium exercise” reduced the asthma symptom score by 0.66 (−0.39 to 1.72), and “High exercise” reduced it significantly by 1.13 (0.03 to 2.22). The effect was strongest among overweight subjects. Conclusions: Our results provide new evidence that regular exercising among young adults improves their asthma control. Thus, advising about exercise should be included as an important part of asthma self-management in clinical practice. [ABSTRACT FROM AUTHOR]