Plasticity of Individual Lung Function States from Childhood to Adulthood.

Rationale: Recent evidence highlights the importance of optimal lung development during childhood for health throughout life. Objectives: To explore the plasticity of individual lung function states during childhood. Methods: Prebronchodilator FEV1 z-scores determined at age 8, 16, and 24 years in the Swedish population-based birth cohort BAMSE (Swedish abbreviation for Child [Barn], Allergy, Milieu, Stockholm, Epidemiological study) (N = 3,069) were used. An unbiased, data-driven dependent mixture model was applied to explore lung function states and individual state chains. Lung function catch-up was defined as participants moving from low or very low states to normal or high or very high states, and growth failure as moving from normal or high or very high states to low or very low states. At 24 years, we compared respiratory symptoms, small airway function (multiple-breath washout), and circulating inflammatory protein levels, by using proteomics, across states. Models were replicated in the independent Dutch population-based PIAMA (Prevention and Incidence of Asthma and Mite Allergy) cohort. Measurements and Main Results: Five lung function states were identified in BAMSE. Lung function catch-up and growth failure were observed in 74 (14.5%) BAMSE participants with low or very low states and 36 (2.4%) participants with normal or high or very high states, respectively. The occurrence of catch-up and growth failure was replicated in PIAMA. Early-life risk factors were cumulatively associated with the very low state, as well as with catch-up (inverse association) and growth failure. The very low state as well as growth failure were associated with respiratory symptoms, airflow limitation, and small airway dysfunction at adulthood. Proteomics identified IL-6 and CXCL10 (C-X-C motif chemokine 10) as potential biomarkers of impaired lung function development. Conclusions: Individual lung function states during childhood are plastic, including catch-up and growth failure.

Associations of improved air quality with lung function growth from childhood to adulthood: the BAMSE study.

BACKGROUND: The beneficial effect of improving air quality on lung function development remains understudied. We assessed associations of changes in ambient air pollution levels with lung function growth from childhood until young adulthood in a Swedish cohort study. METHODS: In the prospective birth cohort BAMSE (Children, Allergy, Environment, Stockholm, Epidemiology (in Swedish)), spirometry was conducted at the 8-year (2002-2004), 16-year (2011-2013) and 24-year (2016-2019) follow-ups. Participants with spirometry data at 8 years and at least one other measurement in subsequent follow-ups were included (1509 participants with 3837 spirometry measurements). Ambient air pollution levels (particulate matter with diameter ≤2.5 µm (PM2.5), particulate matter with diameter ≤10 µm (PM10), black carbon (BC) and nitrogen oxides (NO x )) at residential addresses were estimated using dispersion modelling. Linear mixed effect models were used to estimate associations between air pollution exposure change and lung function development. RESULTS: Overall, air pollution levels decreased progressively during the study period. For example, the median (interquartile range (IQR)) level of PM2.5 decreased from 8.24 (0.92) µg·m-3 during 2002-2004 to 5.21 (0.67) µg·m-3 during 2016-2019. At the individual level, for each IQR reduction of PM2.5 the lung function growth rate increased by 4.63 (95% CI 1.64-7.61) mL per year (p<0.001) for forced expiratory volume in 1 s and 9.38 (95% CI 4.76-14.00) mL per year (p<0.001) for forced vital capacity. Similar associations were also observed for reductions of BC and NO x . Associations persisted after adjustment for potential confounders and were not modified by asthma, allergic sensitisation, overweight, early-life air pollution exposure or dietary antioxidant intake. CONCLUSIONS: Long-term reduction of air pollution is associated with positive lung function development from childhood to young adulthood.

Exploring proteomic plasma biomarkers in eosinophilic and neutrophilic asthma.

BACKGROUND: Few biomarkers identify eosinophilic and neutrophilic asthma beyond cell concentrations in blood or sputum. Finding novel biomarkers for asthma endotypes could give insight about disease mechanisms and guide tailored treatment. Our aim was to investigate clinical characteristics and inflammation-related plasma proteins in relation to blood eosinophil and neutrophil concentrations in subjects with and without asthma. METHODS: We included 24-26-year-old subjects (n = 2063) from the Swedish population-based cohort BAMSE. Subjects with asthma (n = 239) and without asthma (n = 1824) were subdivided based on blood eosinophil and neutrophil concentrations (cut-offs 0.3 × 109 /L and 5.0 × 109 /L, respectively). We measured the levels of 92 plasma proteins using Olink Proseek Multiplex Inflammation Panel Assay. Group statistics tests were used to analyse the data, as well as adjusted multiple logistic regression models. RESULTS: Among subjects with asthma, 21.8% had eosinophilic asthma and 20.5% neutrophilic asthma. Eosinophilic asthma, but not neutrophilic asthma, was associated with a distinct clinical phenotype with, for example, higher proportions of eczema and sensitization. Most plasma proteins that associated with high eosinophil and/or neutrophil blood concentrations in subjects with asthma showed similar associations in subjects without asthma. However, out of these proteins, MMP10 levels were associated with eosinophilic asthma and were significantly higher as compared to controls with high eosinophilic concentration, while CCL4 levels associated with high neutrophil concentration only in subjects with asthma. CONCLUSIONS: Eosinophilic asthma was associated with a clear clinical phenotype. With our definitions, we identified MMP10 as a possible plasma biomarker for eosinophilic asthma and CCL4 was linked to neutrophilic asthma. These proteins should be evaluated further in clinical settings and using sputum granulocytes to define the asthma endotypes.

Quantitative relationships of perfluoroalkyl acids in drinking water associated with serum concentrations above background in adults living near contamination hotspots in Sweden.

Contaminated drinking water (DW) is a major source of exposure to per- and polyfluoroalkyl substances (PFAS) at locations around PFAS production/use facilities and military airports. This study aimed to investigate quantitative relationships between concentrations in DW and serum of nine perfluoroalkyl acids (PFAAs) in Swedish adult populations living near contamination hotspots. Short-chained (PFPeA, PFHxA, PFHpA, and PFBS) and long-chained PFAAs (PFOA, PFNA, PFDA, PFHxS and PFOS) were measured in DW and serum. We matched DW and serum concentrations for a total of 398 subjects living or working in areas receiving contaminated DW and in one non-contaminated area. Thereafter, linear regression analysis with and without adjustments for co-variates was conducted. This enabled to derive (i) serum concentrations at background exposure (CB) from sources other than local DW exposure (i.e. food, dust and textiles) at 0 ng/L DW concentration, (ii) population-mean PFAA serum:water ratios (SWR) and (iii) PFAA concentrations in DW causing observable elevated serum PFAA concentrations above background variability. Median concentrations of the sum of nine PFAAs ranged between 2.8 and 1790 ng/L in DW and between 7.6 and 96.9 ng/mL in serum. DW concentration was the strongest predictor, resulting in similar unadjusted and adjusted regression coefficients. Mean CB ranged from <0.1 (PFPeA, PFHpA, PFBS) to 5.1 ng/mL (PFOS). Serum concentrations increased significantly with increasing DW concentrations for all PFAAs except for PFPeA with SWRs ranging from <10 (PFHxA, PFHpA and PFBS) to 111 (PFHxS). Observed elevated serum concentrations above background variability were reached at DW concentrations between 24 (PFOA) and 357 ng/L (PFHxA). The unadjusted linear regression predictions agreed well with serum concentrations previously reported in various populations exposed to low and high DW levels of PFOA, PFHxS and PFOS. The quantitative relationships derived herein should be helpful to translate PFAA concentrations in DW to concentrations in serum at the population level.

Changes in lifestyle, adiposity, and cardiometabolic markers among young adults in Sweden during the COVID-19 pandemic.

BACKGROUND: The COVID-19 pandemic has impacted on public health in several ways. The aim of the study was to investigate changes in lifestyle, adiposity, and cardiometabolic markers among young adults in Sweden during the COVID-19 pandemic and their determinants. METHODS: The study included 1 004 participants from the population-based birth cohort BAMSE. Anthropometrics, body composition (bioelectric impedance analyses), pulse, and blood pressure were measured before (December 2016-May 2019; mean age 22.6 years) and during (October 2020-June 2021; mean age 25.7 years) the COVID-19 pandemic. Lifestyle changes during the pandemic were assessed through a questionnaire. RESULTS: All measures of adiposity (weight, BMI, body fat percentage, trunk fat percentage) and cardiometabolic markers (blood pressure, pulse) increased during the study period (e.g., body fat percentage by a median of + 0.8% in females, p < 0.001, and + 1.5% in males, p < 0.001). Male sex, non-Scandinavian ethnicity, BMI status (underweight and obesity), and changes in lifestyle factors, e.g., decreased physical activity during the pandemic, were associated with higher increase in BMI and/or adiposity. CONCLUSION: Lifestyle factors, adiposity and cardiometabolic markers may have been adversely affected among young adults in Sweden during the COVID-19 pandemic compared with the preceding years. Targeted public health measures to reduce obesity and improve healthy lifestyle are important to prevent future non-communicable diseases.

SARS-CoV-2-specific B- and T-cell immunity in a population-based study of young Swedish adults.

BACKGROUND: Young adults are now considered major spreaders of coronavirus disease 2019 (COVID-19) disease. Although most young individuals experience mild to moderate disease, there are concerns of long-term adverse health effects. The impact of COVID-19 disease and to which extent population-level immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exists in young adults remain unclear. OBJECTIVE: We conducted a population-based study on humoral and cellular immunity to SARS-CoV-2 and explored COVID-19 disease characteristics in young adults. METHODS: We invited participants from the Swedish BAMSE (Barn [Children], Allergy Milieu, Stockholm, Epidemiology) birth cohort (age 24-27 years) to take part in a COVID-19 follow-up. From 980 participants (October 2020 to June 2021), we here present data on SARS-CoV-2 receptor-binding domain-specific IgM, IgA, and IgG titers measured by ELISA and on symptoms and epidemiologic factors associated with seropositivity. Further, SARS-CoV-2-specific memory B- and T-cell responses were detected for a subpopulation (n = 108) by ELISpot and FluoroSpot. RESULTS: A total of 28.4% of subjects were seropositive, of whom 18.4% were IgM single positive. One in 7 seropositive subjects was asymptomatic. Seropositivity was associated with use of public transport, but not with sex, asthma, rhinitis, IgE sensitization, smoking, or body mass index. In a subset of representative samples, 20.7% and 35.0% had detectable SARS-CoV-2 specific B- and T-cell responses, respectively. B- and T-cell memory responses were clearly associated with seropositivity, but T-cell responses were also detected in 17.2% of seronegative subjects. CONCLUSIONS: Assessment of IgM and T-cell responses may improve population-based estimations of SARS-CoV-2 infection. The pronounced surge of both symptomatic and asymptomatic infections among young adults indicates that the large-scale vaccination campaign should be continued.

Preterm birth reduces the risk of IgE sensitization up to early adulthood: A population-based birth cohort study.

BACKGROUND: Immunoglobulin E (IgE) sensitization is associated with asthma and allergic diseases. Gestational age influences early immune system development, thereby potentially affecting the process of tolerance induction to allergens. OBJECTIVE: To study IgE sensitization to common allergens by gestational age from childhood up to early adulthood. METHODS: Population-based birth cohort, data from the Swedish BAMSE study were used. Allergen-specific IgE antibodies to a mix of common food (fx5) and inhalant (Phadiatop) allergens were analysed at 4, 8, 16 and 24 years. Sensitization was defined as allergen-specific IgE ≥0.35 kUA /L to fx5 and/or Phadiatop at each time point. Using logistic regression and generalized estimated equations, adjusted odds ratios (aORs) for sensitization in relation to gestational age were calculated. Replication was sought within the Swedish twin study STOPPA. RESULTS: In BAMSE, 3522 participants were screened for IgE antibodies during follow-up; of these, 197 (5.6%) were born preterm (<37 gestational weeks) and 330 (9.4%) post-term (≥42 weeks). Preterm birth reduced the risk of sensitization to common food and/or inhalant allergens up to early adulthood by 29% (overall aOR = 0.71; 95% CI: 0.52-0.98), and to food allergens specifically by 40% (overall aOR = 0.60; 95% CI: 0.38-0.93). No relation was found between post-term birth and IgE sensitization at any time point. Replication analyses in STOPPA (N = 675) showed similar risk estimates for sensitization to food and/or inhalant allergens (aOR = 0.72; 95% CI: 0.42-1.21), which resulted in a combined meta-analysis aOR = 0.71 (95% CI: 0.54-0.94). CONCLUSIONS: Our study suggests an inverse association between preterm birth and long-term IgE sensitization.

Predictors of electronic cigarette use and its association with respiratory health and obesity in young adulthood in Sweden; findings from the population-based birth cohort BAMSE.

Despite the growing popularity of electronic cigarettes (e-cigarettes) over the last decade, few epidemiological studies have examined the influence on respiratory health in young adulthood. The aim of this study was to identify factors associated with e-cigarette use in young adulthood in Sweden, and to examine associations between e-cigarette use and lung function, respiratory symptoms, and obesity. This cross-sectional study included 3055 young adults from Sweden and used questionnaire and clinical data obtained at age 22-25 years. The prevalence of current e-cigarette use was 3.9% (n = 120). Few participants reported daily (0.4%) or exclusive (0.8%) use of e-cigarettes. In a multivariable adjusted logistic regression model, e-cigarette use was significantly associated with male gender (OR:3.2; 95% CI:1.5-6.7) and cigarette smoking (OR:14.7; 95% CI:5.5-39.0 for daily smoking). Prevalence of cough (15.0% vs. 8.5%) and mucus production (22.3% vs. 14.8%) was significantly higher among e-cigarette users compared to non-users, while no difference in lung function was observed. In addition, the prevalence of overweight/obesity was higher among e-cigarette users compared to non-users (36.7% vs. 22.3% with BMI≥25 kg/m2). In conclusion, cigarette smokers and males used e-cigarette more often compared to females and non-cigarette smokers. Attention should be given to respiratory symptoms among e-cigarette users, although our results may be explained by the concurrent use of conventional cigarettes, as the group of exclusive e-cigarette users were too small to allow firm conclusions.

COVID-19 among young adults in Sweden: self-reported long-term symptoms and associated factors.

AIMS: The main aim of the study was to describe self-reported symptoms of COVID-19 and examine if long-term symptoms are associated with lifestyle factors or common chronic diseases among Swedish young adults. A secondary aim was to compare the prevalence of smoking and snuff use before and during the COVID-19 pandemic. METHODS: The study population includes 1644 participants aged 23-26 years from the Swedish population-based birth cohort BAMSE. From August to November 2020, the participants answered a web questionnaire on COVID-19 symptoms, lifestyle and health. Information on tobacco use was compared against the previous study follow-up in 2016-2019. RESULTS: The prevalence of suspected COVID-19 symptoms was 45.3% (n=742), and 80 of these (10.8%) reported long-term symptoms (⩾4 weeks). There was no significant difference in sociodemographic or lifestyle factors in relation to the duration of suspected COVID-19 symptoms. Rhinitis, migraine and lower self-rated health before the pandemic was more common among participants with long-term symptoms. In addition, there was a tendency for higher prevalences of asthma, chronic bronchitis and depression in this group. The prevalence of smoking decreased from 18.9% before the pandemic to 14.7% during the pandemic, while snuff use increased from 12.7% to 22.4% (P<0.001). CONCLUSIONS: Almost half of Swedish young adults have had symptoms of suspected COVID-19 from February up to August 2020. Among these, one out of 10 have had long-term symptoms for at least 4 weeks. Long-term symptoms of suspected COVID-19 were associated with several common chronic conditions. Smoking may have decreased during the pandemic, while snuff use may have increased.

Early-life risk factors for reversible and irreversible airflow limitation in young adults: findings from the BAMSE birth cohort.

We aimed to determine prevalence and early-life risk factors for reversible and irreversible airflow limitation in young adults from the general population. Among young adults in their 20s, the prevalence was 5.3% for reversible airflow limitation and 2.0% for irreversible airflow limitation. While parental asthma was the only risk factor for development of reversible airflow limitation, the risk factors for development of irreversible airflow limitation were current asthma, childhood respiratory tract infections and asthma, and exposure to air pollution.

Assessment of chronic bronchitis and risk factors in young adults: results from BAMSE.

BACKGROUND: Chronic bronchitis is associated with substantial morbidity among elderly adults, but little is known about its prevalence and risk factors in young adults. Our aim was to assess the prevalence and early-life risk factors for chronic bronchitis in young adults. METHODS: Questionnaire data and clinical measures from the 24-year follow-up of the Swedish BAMSE (Child (Barn), Allergy, Milieu, Stockholm, Epidemiological) cohort were used. We assessed chronic bronchitis (CB) as the combination of cough and mucus production in the morning during winter. Environmental and clinical data from birth and onwards were used for analyses of risk factors. RESULTS: At the 24-year follow-up, 75% (n=3064) participants completed the questionnaire and 2030 performed spirometry. The overall prevalence of CB was 5.5% (n=158) with similar estimates in males and females. 49% of CB cases experienced more than three self-reported respiratory infections in the past year compared to 18% in non-CB subjects (p<0.001), and 37% of cases were current smokers (versus 19% of non-CB cases). Statistically significant lower post-bronchodilator forced expiratory volume in 1 s/forced vital capacity were observed in CB compared to non-CB subjects (mean z-score -0.06 versus 0.13, p=0.027). Daily smoking (adjusted (a)OR 3.85, p<0.001), air pollution exposure (black carbon at ages 1-4 years aOR 1.71 per 1 µg·m-3 increase, p=0.009) and exclusive breastfeeding for ≤4 months (aOR 0.66, p=0.044) were associated with CB. CONCLUSION: Chronic bronchitis in young adults is associated with recurrent respiratory infections. Besides smoking, our results support the role of early-life exposures, such as air pollution and exclusive breastfeeding, for respiratory health later in life.

Exposure to environmental phthalates during preschool age and obesity from childhood to young adulthood.

Obesity rates are increasing globally, and recent theories suggest that phthalates may contribute to obesity development. This longitudinal study aimed to investigate associations between environmental phthalate exposure during childhood and obesity, utilizing data from 100 participants from a Swedish birth cohort. The participants were followed repeatedly from birth and provided spot urine samples at 4 years. Weight and height were measured at ages 4, 8, 16 and 24 years, as well as additional anthropometric indices at 24 years. Urine samples were analysed for 10 phthalate metabolites using liquid chromatography tandem mass spectrometry. Generalized estimating equation models were performed to assess overall and age-specific associations between urinary phthalate concentrations and BMI groups; thin/normal weight vs overweight/obese. After adjustment for potential confounders, overall associations were observed for diisononyl phthalate (DiNP) metabolites mono(oxo-isononyl) phthalate (MOiNP) (OR per increase ng/ml: 1.18; 95% CI: 1.05, 1.33), mono(carboxy-isooctyl) phthalate (MCiOP) (OR: 1.06; 95% CI: 1.01, 1.11) and ∑DiNP (OR: 1.02; 95% CI:1.00, 1.04) and development of overweight/obesity up to age 24 years. Age-specific associations were observed for the same metabolites at 8, 16 and 24 years. Furthermore, linear regression analysis revealed associations between increased body fat % at age 24 years and MHiNP (ß: 2.42; 95% CI: 0.44, 4.39), MOiNP (ß: 2.32; 95% CI: 0.46, 4.18), MCiOP (ß: 2.65; 95% CI: 0.41, 4.89) and ∑DiNP (ß: 2.65; 95% CI: 0.52, 4.77). These findings suggest that DiNP exposure during preschool age may be associated with subsequent obesity, however these findings need to be corroborated by further research.

Low-level exposure to polycyclic aromatic hydrocarbons is associated with reduced lung function among Swedish young adults.

BACKGROUND: Exposure to polycyclic aromatic hydrocarbons (PAHs) has been linked to adverse pulmonary effects. However, the impact of low-level environmental PAH exposure on lung function in early adulthood remains uncertain. OBJECTIVES: To evaluate the associations between urinary PAH metabolites and lung function parameters in young adults. METHODS: Urinary metabolites of pyrene, phenanthrene, and fluorene were analysed in 1000 young adults from Sweden (age 22-25 years) using LC-MS/MS. Lung function and eosinophilic airway inflammation were measured by spirometry and exhaled nitric oxide fraction (FeNO), respectively. Linear regression analysis was used to evaluate associations between PAH metabolites and the outcomes. RESULTS: Median urinary concentrations of 1-OH-pyrene, ∑OH-phenanthrene, and ∑OH-fluorene were 0.066, 0.36, 0.22 µg/L, respectively. We found inverse associations of ∑OH-phenanthrene and ∑OH-fluorene with FEV1 and FVC, as well as between 1-OH-pyrene and FEV1/FVC ratio (adjusted P < 0.05; all participants). An increase of 1% in ∑OH-fluorene was associated with a decrease of 73 mL in FEV1 and 59 mL in FVC. In addition, ∑OH-phenanthrene concentrations were, in a dose-response manner, inversely associated with FEV1 (B from -109 to -48 compared with the lowest quartile of ∑OH-phenanthrene; p trend 0.004) and FVC (B from -159 to -102 compared with lowest quartile; p-trend <0.001). Similar dose-response associations were also observed between ∑OH-fluorene and FEV1 and FVC, as well as between 1-OH-pyrene and FEV1/FVC (p-trend <0.05). There was no association between PAH exposure and FeNO, nor was there an interaction with smoking, sex, or asthma. CONCLUSION: Low-level PAH exposure was, in a dose-response manner, associated with reduced lung function in young adults. Our findings have public health implications due to i) the widespread occurrence of PAHs in the environment and ii) the clinical relevance of lung function in predicting all-cause and cardiovascular disease mortality.

Comparison of personal exposure to black carbon levels with fixed-site monitoring data and with dispersion modelling and the influence of activity patterns and environment.

BACKGROUND: Short-term studies of health effects from ambient air pollution usually rely on fixed site monitoring data or spatio-temporal models for exposure characterization, but the relation to personal exposure is often not known. OBJECTIVE: We aimed to explore this relation for black carbon (BC) in central Stockholm. METHODS: Families (n = 46) with an infant, one parent working and one parent on parental leave, carried battery-operated BC instruments for 7 days. Routine BC monitoring data were obtained from rural background (RB) and urban background (UB) sites. Outdoor levels of BC at home and work were estimated in 24 h periods by dispersion modelling based on hourly real-time meteorological data, and statistical meteorological data representing annual mean conditions. Global radiation, air pressure, precipitation, temperature, and wind speed data were obtained from the UB station. All families lived in the city centre, within 4 km of the UB station. RESULTS: The average level of 24 h personal BC was 425 (s.d. 181) ng/m3 for parents on leave, and 394 (s.d. 143) ng/m3 for working parents. The corresponding fixed-site monitoring observations were 148 (s.d. 139) at RB and 317 (s.d. 149) ng/m3 at UB. Modelled BC levels at home and at work were 493 (s.d. 228) and 331 (s.d. 173) ng/m3, respectively. UB, RB and air pressure explained only 21% of personal 24 h BC variability for parents on leave and 25% for working parents. Modelled home BC and observed air pressure explained 23% of personal BC, and adding modelled BC at work increased the explanation to 34% for the working parents. IMPACT: Short-term studies of health effects from ambient air pollution usually rely on fixed site monitoring data or spatio-temporal models for exposure characterization, but the relation to actual personal exposure is often not known. In this study we showed that both routine monitoring and modelled data explained less than 35% of variability in personal black carbon exposure. Hence, short-term health effects studies based on fixed site monitoring or spatio-temporal modelling are likely to be underpowered and subject to bias.

Post COVID-19 symptoms are common, also among young adults in the general population.

Post coronavirus disease-19 (post COVID-19) is mainly studied in clinical populations and less is known about post COVID-19 in a young general population. The aim of the study is to investigate the prevalence and symptoms of post COVID-19 and its potential risk factors in young adults. Participants from the Swedish population-based birth cohort BAMSE were included (n = 2022, mean age 26.5 years). Post COVID-19 was assessed through a questionnaire and defined as symptoms after confirmed COVID-19 (registry-based or self-reported positive test) lasting for ≥ 2 months. In total, 681 participants had had confirmed COVID-19. Among them, 112 (16.5%) fulfilled the definition of post COVID-19 (17.8% in females, 14.5% in males, p = 0.26). The most common post COVID-19 symptoms were altered smell and taste (68.8%), dyspnea (33.7%) and fatigue (30.4%). Overall, no major risk factors for post COVID-19 were identified except for being bedbound during COVID-19. However, asthma and rhinitis were associated with the post COVID-19 symptom dyspnea, migraine with altered smell and taste, and lower self-rated health with fatigue. In conclusion, post COVID-19 symptoms are common, also among young adults in the general population. Although not life-threatening, it could have a considerable impact on public health due to the high prevalence and long-term symptoms.

Assessing tobacco use in Swedish young adults from self-report and urinary cotinine: a validation study using the BAMSE birth cohort.

OBJECTIVES: Studies on health effects of tobacco often rely on self-reported exposure data, which is subjective and can lead to misclassification. The aim of this study was to describe the prevalence of cigarette smoking, snus and e-cigarette use, as well as to validate self-reported tobacco use among young adults in Sweden. METHOD: Participants of a population-based Swedish cohort (n=3052), aged 22-25 years, assessed their tobacco use in a web questionnaire. Urinary cotinine was analysed in a subsample of the study population (n=998). The agreement between self-reported tobacco use and urinary cotinine was assessed using Cohen's Kappa coefficient (κ) at a cut-off level of 50 ng/mL. RESULTS: Patterns of tobacco use differed between men and women. Among men, 20.0% reported daily snus use, 5.8% daily cigarette smoking and 5.6% any e-cigarette use. In contrast, 3.2% of the women reported daily snus use, 9.0% daily cigarette smoking and 2.4% any e-cigarette use. Among the tobacco use categories, daily snus users had the highest levels of cotinine. Of reported non-tobacco users, 3.5% had cotinine levels above the cut-off, compared with 68.0% among both occasional cigarette smokers and snus users, 67.5% among all e-cigarette users and 94.7% and 97.8% among daily cigarette smokers and snus users, respectively. Agreement between self-reported tobacco use and urinary cotinine was classified as strong for daily use of cigarettes (κ=0.824) and snus (κ=0.861), while moderate to weak for occasional smoking (κ=0.618), occasional snus use (κ=0.573) and any e-cigarette use (κ=0.576). CONCLUSIONS: We found high validity of self-reported tobacco use in our study population, particularly for daily tobacco use. Further, we found that daily snus users were exposed to high levels of cotinine. Together with previous findings, our results indicate good validity of self-reported tobacco use among young adults.

Ambient air pollution exposure linked to long COVID among young adults: a nested survey in a population-based cohort in Sweden.

Background: Post COVID-19 conditions, also known as long COVID, are of public health concern, but little is known about their underlying risk factors. We aimed to investigate associations of air pollution exposure with long COVID among Swedish young adults. Methods: We used data from the BAMSE (Children, Allergy, Environment, Stockholm, Epidemiology [in Swedish]) cohort. From October 2021 to February 2022 participants answered a web-questionnaire focusing on persistent symptoms following acute SARS-CoV-2 infection. Long COVID was defined as symptoms after confirmed infection with SARS-CoV-2 lasting for two months or longer. Ambient air pollution levels (particulate matter ≤2.5 µm [PM2.5], ≤10 µm [PM10], black carbon [BC] and nitrogen oxides [NOx]) at individual-level addresses were estimated using dispersion modelling. Findings: A total of 753 participants with SARS-CoV-2 infection were included of whom 116 (15.4%) reported having long COVID. The most common symptoms were altered smell/taste (n = 80, 10.6%), dyspnea (n = 36, 4.8%) and fatigue (n = 34, 4.5%). Median annual PM2.5 exposure in 2019 (pre-pandemic) was 6.39 (interquartile range [IQR] 6.06-6.71) µg/m3. Adjusted Odds Ratios (95% confidence intervals) of PM2.5 per IQR increase were 1.28 (1.02-1.60) for long COVID, 1.65 (1.09-2.50) for dyspnea symptoms and 1.29 (0.97-1.70) for altered smell/taste. Positive associations were found for the other air pollutants and remained consistent across sensitivity analyses. Associations tended to be stronger among participants with asthma, and those having had COVID during 2020 (versus 2021). Interpretation: Ambient long-term PM2.5 exposure may affect the risk of long COVID in young adults, supporting efforts for continuously improving air quality. Funding: The study received funding from the Swedish Research Council (grant no. 2020-01886, 2022-06340), the Swedish Research Council for Health, Working life and Welfare (FORTE grant no. 2017-01146), the Swedish Heart-Lung Foundation, Karolinska Institute (no. 2022-01807) and Region Stockholm (ALF project for cohort and database maintenance).

Combined Exposure to Birch Pollen and Thunderstorms Affects Respiratory Health in Stockholm, Sweden-A Time Series Analysis.

BACKGROUND: Thunderstorm asthma is a term used to describe surges in acute respiratory illnesses following a thunderstorm and is often attributed to an intense exposure to aeroallergens. Several episodes of thunderstorm asthma have been observed worldwide; however, no such cases have been described in Sweden. In Sweden, the most prominent exposure to air-borne pollen occurs during the blooming of the birch. We aimed to explore the associations between respiratory health and the combined exposure to thunderstorms and birch pollen. METHODS: We investigated the association between the daily numbers of outpatient visits due to respiratory cases and the combined exposure to thunderstorms and birch pollen during the period of 1 May-31 September in 2001-2017, in Stockholm County, Sweden, by using time series analysis with log linear models. RESULTS: We detected noticeable increases in the number of outpatient visits on both the same day (max 26%; 95% CI 1.16-1.37) and the day after (max 50%; 95% CI 1.32-1.70) the occurrence of a thunderstorm, when the concentrations of birch pollen and the number of lightning discharges were within the highest categories. CONCLUSIONS: It is possible that co-exposure to heavy thunderstorms and high concentrations of birch pollen affects the respiratory health of the Stockholm population. To the best of our knowledge, this is the first study addressing the thunderstorm-related respiratory illnesses in Sweden and the effects of birch pollen. Our study may be important for future public health advice related to thunderstorm asthma.