Early smoke exposure is associated with asthma and lung function deficits in adolescents

Do early-life allergic sensitization and respiratory infection interact to increase asthma risk?

OBJECTIVE

The 'two-hit' hypothesis theorizes that early life allergic sensitization and respiratory infection interact to increase asthma risk.

METHODS

We sought to determine in a high allergy risk birth cohort whether interactions between early life allergic sensitization and respiratory infection were associated with increased risk for asthma at ages 6-7 years and 18 years. Allergic sensitization was assessed at 6, 12, and 24 months by skin prick testing to 3 food and 3 aeroallergens. Respiratory infection was defined as reported "cough, rattle, or wheeze" and assessed 4-weekly for 15 months, at 18 months, and age 2 years. Regression analysis was undertaken with parent-reported asthma at age 6-7 years and doctor diagnosed asthma at 18 years as distinct outcomes. Interactions between allergic sensitization and respiratory infection were explored with adjustment made for potential confounders.

RESULTS

Odds of asthma were higher in sensitized compared to nonsensitized children at age 6-7 years (OR = 14.46; 95% CI 3.99-52.4), There was no evidence for interactions between allergic sensitization and early life respiratory infection, with a greater frequency of respiratory infection up to 2 years of age associated with increased odds for asthma at age 6-7 years in both sensitized (OR = 1.13; 95% CI 1.02-1.25, n = 199) and nonsensitized children (OR = 1.31; 1.11-1.53, n = 211) (p interaction = 0.089). At age 18 years, these associations were weaker.

CONCLUSIONS

Our findings do not support 'two-hit' interactions between early life allergic sensitization and respiratory infection on asthma risk. Both early life respiratory infections and allergic sensitization were risk factors and children with either should be monitored closely for development of asthma.

Predictors of lung function in early adulthood: A population-based cohort study

BACKGROUND AND OBJECTIVE

Lung function reaches a peak/plateau in early adulthood before declining with age. Lower early adult lung function may increase the risk for chronic obstructive pulmonary disease (COPD) in mid-late adult life. Understanding the effects of multiple childhood/adolescent exposures and their potential interactions on plateau lung function would provide insights into the natural history of COPD.

METHODS

Longitudinal spirometry data from 688 participants with complete data from a population-based birth cohort (original n = 1037) were used to investigate associations between a wide range of childhood/adolescent exposures and repeated measures of FEV1, FVC and FEV1/FVC during the early-adult plateau phase. Generalized estimating equations were used to accommodate the multiple timepoints per participant.

RESULTS

FEV1 reached a peak/plateau between ages 18 and 26 and FVC from 21 to 32 years, whereas FEV1/FVC declined throughout early adulthood. Childhood asthma and airway hyperresponsiveness were associated with lower early adult FEV1 and FEV1/FVC. Smoking by age 18 was associated with lower FEV1/FVC. Higher BMI during early adulthood was associated with lower FEV1 and FVC and lower FEV1/FVC. Physical activity during adolescence was positively associated with FEV1 and FEV1/FVC but this was only statistically significant in men. There was no convincing evidence of interactions between exposures.

CONCLUSION

Childhood asthma and airway hyperresponsiveness are associated with lower lung function in early adulthood. Interventions targeting these may reduce the risk of COPD in mid-late adult life. Promotion of physical activity during adolescence, prevention of cigarette smoking and maintenance of a healthy body weight in early adulthood are also priorities.

The impact of exposure to tobacco smoke and e-cigarettes on asthma-related outcomes: Systematic review informing the EAACI guidelines on environmental science for allergic diseases and asthma

To inform the clinical practice guidelines' recommendations developed by the European Academy of Allergy and Clinical Immunology systematic reviews (SR) assessed using GRADE on the impact of environmental tobacco smoke (ETS) and active smoking on the risk of new-onset asthma/recurrent wheezing (RW)/low lung function (LF), and on asthma-related outcomes. Only longitudinal studies were included, almost all on combustion cigarettes, only one assessing e-cigarettes and LF. According to the first SR (67 studies), prenatal ETS increases the risk of RW (moderate certainty evidence) and may increase the risk of new-onset asthma and of low LF (low certainty evidence). Postnatal ETS increases the risk of new-onset asthma and of RW (moderate certainty evidence) and may impact LF (low certainty evidence). Combined in utero and postnatal ETS may increase the risk of new-onset asthma (low certainty evidence) and increases the risk of RW (moderate certainty evidence). According to the second SR (24 studies), ETS increases the risk of severe asthma exacerbations and impairs asthma control and LF (moderate certainty evidence). According to the third SR (25 studies), active smoking increases the risk of severe asthma exacerbations and of suboptimal asthma control (moderate certainty evidence) and may impact asthma-related quality-of-life and LF (low certainty evidence).

Epigenetic Features in Newborns Associated with Preadolescence Lung Function and Asthma Acquisition during Adolescence

The association between newborn DNA methylation (DNAm) and asthma acquisition (AA) during adolescence has been suggested. Lung function (LF) has been shown to be associated with asthma risk and its severity. However, the role of LF in the associations between DNAm and AA is unclear, and it is also unknown whether the association between DNAm and AA is consistent with that between DNAm and LF. We address this question through assessing newborn epigenetic features of preadolescence LF and of AA during adolescence, along with their biological pathways and processes. Our study's primary medical significance lies in advancing the understanding of asthma's early life origins. By investigating epigenetic markers in newborns and their association with lung function in preadolescence, we aim to uncover potential early biomarkers of asthma risk. This could facilitate earlier detection and intervention strategies. Additionally, exploring biological pathways linking early lung function to later asthma development can offer insights into the disease's pathogenesis, potentially leading to novel therapeutic targets.

METHODS

The study was based on the Isle of Wight Birth cohort (IOWBC). Female subjects with DNAm data at birth and with no asthma at age 10 years were included (n = 249). The R package ttScreening was applied to identify CpGs potentially associated with AA from 10 to 18 years and with LF at age 10 (FEV1, FVC, and FEV1/FVC), respectively. Agreement in identified CpGs between AA and LF was examined, along with their biological pathways and processes via the R function gometh. We tested the findings in an independent cohort, the Avon Longitudinal Study of Parents and Children (ALSPAC), to examine overall replicability.

RESULTS

In IOWBC, 292 CpGs were detected with DNAm associated with AA and 1517 unique CpGs for LF (514 for FEV1, 436 for FVC, 408 for FEV1/FVC), with one overlapping CpG, cg23642632 (NCKAP1) between AA and LF. Among the IOWBC-identified CpGs, we further tested in ALSPAC and observed the highest agreement between the two cohorts in FVC with respect to the direction of association and statistical significance. Epigenetic enrichment analyses indicated non-specific connections in the biological pathways and processes between AA and LF.

CONCLUSIONS

The present study suggests that FEV1, FVC, and FEV1/FVC (as objective measures of LF) and AA (incidence of asthma) are likely to have their own specific epigenetic features and biological pathways at birth. More replications are desirable to fully understand the complexity between DNAm, lung function, and asthma acquisition.

Short-term smoking cessation leads to a universal decrease in whole blood genomic DNA methylation in patients with a smoking history

BACKGROUND

Epigenetics is involved in various human diseases. Smoking is one of the most common environmental factors causing epigenetic changes. The DNA methylation changes and mechanisms after quitting smoking have yet to be defined. The present study examined the changes in DNA methylation levels before and after short-term smoking cessation and explored the potential mechanism.

METHODS

Whole blood and clinical data were collected from 8 patients before and after short-term smoking cessation, DNA methylation was assessed, and differentially methylated sites were analyzed, followed by a comprehensive analysis of the differentially methylated sites with clinical data. GO/KEGG enrichment and protein-protein interaction (PPI) network analyses identified the hub genes. The differentially methylated sites between former and current smokers in GSE50660 from the GEO database were detected by GEO2R. Then, a Venn analysis was carried out using the differentially methylated sites. GO/KEGG enrichment analysis was performed on the genes corresponding to the common DNA methylation sites, the PPI network was constructed, and hub genes were predicted. The enriched genes associated with the cell cycle were selected, and the pan-cancer gene expression and clinical significance in lung cancer were analyzed based on the TCGA database.

RESULTS

Most genes showed decreased DNA methylation levels after short-term smoking cessation; 694 upregulated methylation CpG sites and 3184 downregulated methylation CpG sites were identified. The DNA methylation levels were altered according to the clinical data (body weight, expiratory, and tobacco dependence score). Enrichment analysis, construction of the PPI network, and pan-cancer analysis suggested that smoking cessation may affect various biological processes.

CONCLUSIONS

Smoking cessation leads to epigenetic changes, mainly decreased in the decline of most DNA methylation levels. Bioinformatics further identified the biologically relevant changes after short-term smoking cessation.

The relationship of early-life household air pollution with childhood asthma and lung function

The increase in childhood asthma over the past few decades has made it an important public health issue. Poor lung function growth associated with some phenotypes of asthma compounds its long-term impact on the individual. Exposure to early-life household risk factors is believed to be linked with respiratory health while infants' lungs are still developing. This review summarises epidemiological studies and mechanistic evidence focusing on the detrimental effects of early-life household air exposures on the respiratory health of children, in particular effects on asthma and lung function. Many early-life household air exposures, including tobacco smoke, gases from heating and cooking, mould/dampness and cleaning products are associated with childhood asthma development and lung function growth. These exposures may alter structural and mechanical characteristics of infants' lungs and contribute to deficits in later life. In addition, some risk factors, including tobacco smoke and cleaning products, can transmit effects across generations to increase the risk of asthma in subsequent generations. This review supports the hypothesis that risks of asthma and accelerated lung ageing are established in early life. The timing of exposure may be critical in the pathogenesis of respiratory diseases, in terms of future risk of asthma and reduced lung function in adults.

Interactions between glutathione S-transferase genes and household air pollution on asthma and lung function

Oxidative stress is one of the main pathophysiological mechanisms for chronic respiratory disease. Glutathione S-transferase (GST) genes play important roles in antioxidant defences and may influence respiratory health. Although there is not consistent evidence that the three commonly studied genes of GSTM1, GSTT1 and GSTP1 are associated directly with respiratory outcomes, they seem to be related to disease susceptibility if exposure interactions are taken into account. Exposure to household air pollution may be particularly important in increasing lung oxidative stress. This review summarizes the relationships between GST genes, household air pollution and asthma and impaired lung function. Our findings support a role for GST polymorphisms in susceptibility to asthma and impaired lung function via oxidative stress pathways. Future research should additionally consider the role of gene-gene interactions, multiple environmental exposures, and gender in these complex associations, that are involved in maintaining antioxidant defences and lung health.

Early-life exposure to tobacco smoke alters airway signaling pathways and later mortality in D. melanogaster

Early life environmental influences such as exposure to cigarette smoke (CS) can disturb molecular processes of lung development and thereby increase the risk for later development of chronic respiratory diseases. Among the latter, asthma and chronic obstructive pulmonary disease (COPD) are the most common. The airway epithelium plays a key role in their disease pathophysiology but how CS exposure in early life influences airway developmental pathways and epithelial stress responses or survival is poorly understood. Using Drosophila melanogaster larvae as a model for early life, we demonstrate that CS enters the entire larval airway system, where it activates cyp18a1 which is homologues to human CYP1A1 to metabolize CS-derived polycyclic aromatic hydrocarbons and further induces heat shock protein 70. RNASeq studies of isolated airways showed that CS dysregulates pathways involved in oxidative stress response, innate immune response, xenobiotic and glutathione metabolic processes as well as developmental processes (BMP, FGF signaling) in both sexes, while other pathways were exclusive to females or males. Glutathione S-transferase genes were further validated by qPCR showing upregulation of gstD4, gstD5 and gstD8 in respiratory tracts of females, while gstD8 was downregulated and gstD5 unchanged in males. ROS levels were increased in airways after CS. Exposure to CS further resulted in higher larval mortality, lower larval-pupal transition, and hatching rates in males only as compared to air-exposed controls. Taken together, early life CS induces airway epithelial stress responses and dysregulates pathways involved in the fly's branching morphogenesis as well as in mammalian lung development. CS further affected fitness and development in a highly sex-specific manner.

Focus on Early COPD: Definition and Early Lung Development

Chronic obstructive pulmonary disease (COPD) is a disease with high incidence rate and mortality rates worldwide. It is the third leading cause of death in the world. Nevertheless, little progress has been made in treating and preventing the disease. Under these circumstances, the concept of “early COPD” was proposed. Although this concept is not new, most health-care workers do not fully understand early COPD and tend to confuse it with mild COPD. In this review, we mainly discuss the definition of early COPD and the developmental trajectory of lung function. Although patients with early COPD have no symptoms, their lung function is already lower than that of normal people. A relatively complete definition is needed to identify this group of people. Reduced lung function is the diagnostic criterion for COPD, but lung development is a long-term dynamic process. In addition to smoking and air pollution, we should pay more attention to prenatal and childhood risk factors, for example, parents smoking, birth weight, preterm birth, mode of delivery, childhood respiratory infections and childhood asthma. Health-care workers need to be fully aware of early COPD, to reduce the morbidity of COPD and take effective measures to prevent these risk factors.

Prevalence and Determinants of Tobacco Smoking Among Low-Income Urban Adolescents

Background: Tobacco-smoking in children is one of the most crucial public health concerns, which could be highly prevalent in underprivileged populations. Methods: A cross sectional, random sampling survey was conducted to determine the prevalence of current tobacco-smoking and related risk factors among adolescents living in a low-income area of Santiago de Chile. Results: Of the 2,747 adolescents participating in the study, 24.0% [95% confidence interval (CI) 22.3-25.5] were current smokers, with no significant difference between girls and boys. Factors associated with current smoking were as follows: positive attitude to smoking cigarettes offered by peers [odds ratio (OR) 8.0; 95% CI 5.7-11.3, P < 0.001], having smoking best friends (OR 4.0; 95% CI 2.6-6.0, P < 0.001), and passive smoking in the house (OR 1.9; 95% CI 1.2-3.1, P = 0.008). A total of 16.8% (95% CI 11.4-18.2) of children had smoked an entire cigarette at the age of ≤12, and 62.3% (95% CI, 60.5-64.1) were passive smokers at home. Regarding nonsmoking children, 52.4% (95% CI 49.74-55.06) were exposed to tobacco smoke at home. Conclusion: The prevalence of current tobacco-smoking in adolescents is high and increasing compared to previous studies undertaken in the selected low-resourced area. Two-thirds of children who started smoking before the age of 12 years were current smokers at the time of the survey, highlighting the prevalence of the powerful addiction generated and the need for better preventive strategies against tobacco-smoking for children living in low-resource communities.

Prenatal smoke exposure dysregulates lung epithelial cell differentiation in mouse offspring: role for AREG-induced EGFR signaling

Prenatal smoke exposure is a risk factor for impaired lung development in children. Recent studies have indicated that amphiregulin (AREG), which is a ligand of the epidermal growth factor receptor (EGFR), has a regulatory role in airway epithelial cell differentiation. In this study, we investigated the effect of prenatal smoke exposure on lung epithelial cell differentiation and linked this with AREG-EGFR signaling in 1-day-old mouse offspring. Bronchial and alveolar epithelial cell differentiations were assessed by immunohistochemistry. Areg, epidermal growth factor (Egf), and mRNA expressions of specific markers for bronchial and alveolar epithelial cells were assessed by RT-qPCR. The results in neonatal lungs were validated in an AREG-treated three-dimensional mouse lung organoid model. We found that prenatal smoke exposure reduced the number of ciliated cells and the expression of the cilia-related transcription factor Foxj1, whereas it resulted in higher expression of mucus-related transcription factors Spdef and Foxm1 in the lung. Moreover, prenatally smoke-exposed offspring had higher numbers of alveolar epithelial type II cells (AECII) and lower expression of the AECI-related Pdpn and Gramd2 markers. This was accompanied by higher expression of Areg and lower expression of Egf in prenatally smoke-exposed offspring. In bronchial organoids, AREG treatment resulted in fewer ciliated cells and more basal cells when compared with non-treated bronchiolar organoids. In alveolar organoids, AREG treatment led to more AECII cells than non-treated AECII cells. Taken together, the observed impaired bronchial and alveolar cell development in prenatally smoke-exposed neonatal offspring may be induced by increased AREG-EGFR signaling.

Lung function changes in patients with chronic obstructive pulmonary disease (COPD) and asthma exposed to secondhand smoke in outdoor areas

BACKGROUND

Further evidence is needed on the effects that short- and long-term exposure to secondhand smoke (SHS) have on the respiratory health of patients with lung disease. Within the TackSHS project we aimed to assess the acute respiratory effects in lung function that result from short-term SHS exposure among patients with asthma and chronic obstructive pulmonary disease (COPD).

METHODS

The study design was an intervention trial with measurements before/after exposure to SHS in legal outdoor smoking areas. We studied patients with asthma or COPD from Czechia, Ireland, and Spain. Forced spirometry, peak flow and carbon monoxide (CO) measurements were performed pre- and 24 h post- exposure.

RESULTS

Overall, 60 patients were studied, 30 with asthma, and 30 with COPD; 35 (58.3%) were female. There were no significant differences observed in exhaled CO between pre- and 24 h post-exposure neither in women (p = 0.210), nor in men (p = 0.169).A statistically significant decrease in forced vital capacity (FVC) was seen, overall, in asthma participants (p = 0.02) and in forced expiratory volume in the first second (FEV₁), (p = 0.02), FVC (p = 0.04) and peak expiratory flow rate (PEFR) (p = 0.04) in female asthmatic participants. The observed decreases in respiratory measurements in COPD were not significant. There were no reported increases in symptoms, respiratory medication, or use of health services 24 h after the exposure.

CONCLUSION

We conclude that acute, short-term SHS exposure had a statistically significant effect on spirometry in female asthma patients but did not significantly modify spirometric indices 24 h later in COPD patients.

Lung functional development and asthma trajectories

Early life environmental risk factors are associated with chronic respiratory morbidity in child- and adulthood. A possible mechanism for this sustained effect is their influence on early life lung functional growth and development, a susceptible phase of rapid lung growth with increased plasticity. We summarize evidence of hereditary and environmental ante-, peri-, and early postnatal factors on lung functional development, such as air pollution, tobacco exposure, nutrition, intrauterine growth retardation, prematurity, early life infections, microbiome, and allergies and their effect on lung functional trajectories. While some of the factors (e.g., prematurity) directly impair lung growth, the influence of many environmental factors is mediated through inflammatory processes (e.g., recurrent infections or oxidative stress). The timing and nature of these influences and their impact result in degrees of impaired maximal lung functional capacity in early adulthood; and they potentially impact future long-term respiratory morbidity such as chronic asthma or chronic obstructive airway disease (COPD). We discuss possibilities to prevent or modify such early abnormal lung functional growth trajectories and the need for future studies and prevention programs.

Timing of secondhand smoke, pet, dampness or mould exposure and lung function in adolescence

BACKGROUND

The relevance of timing of exposure in the associations of secondhand tobacco smoke (SHS), pets, and dampness or mould exposure with lung function is unclear. We investigated the relevance of timing of these exposures for lung function in adolescence.

METHODS

We used data from participants of the Dutch Prevention and Incidence of Asthma and Mite Allergy (PIAMA) cohort with spirometric measurements at ages 12 and 16 years (n=552). Data on residential exposure to SHS, pets, and dampness or mould were obtained by repeated parental questionnaires. We characterised timing of exposure through longitudinal patterns using latent class growth modelling and assessed associations of these patterns with FEV₁ and FVC at ages 12 and 16 and FEV₁ and FVC growth between ages 12 and 16 using linear regression models.

RESULTS

Childhood SHS exposure was associated with reduced FEV₁ growth/year (95% CI) (-0.34% (-0.64% to -0.04%)). Late childhood and early life pet exposure was associated with increased FEV₁ growth (0.41% (0.14% to 0.67%)) and reduced FVC growth (-0.28% (-0.53% to -0.03%)), respectively, compared with very low exposure. Early life dampness or mould exposure was associated with reduced lung function growth. All time windows of SHS exposure tended to be associated with lower attained lung function and pet exposure tended to be associated with higher FEV₁.

CONCLUSION

SHS exposure during childhood could lead to reduced lung function growth and lower attained lung function in adolescence. While pet exposure in late childhood may not adversely affect lung function, early childhood pet exposure may slow down FVC growth in adolescence.

In utero exposure to cigarette smoke and effects across generations: A conference of animals on asthma

BACKGROUND

The prevalence of asthma and chronic obstructive pulmonary disease (COPD) has risen markedly over the last decades and is reaching epidemic proportions. However, underlying molecular mechanisms are not fully understood, hampering the urgently needed development of approaches to prevent these diseases. It is well established from epidemiological studies that prenatal exposure to cigarette smoke is one of the main risk factors for aberrant lung function development or reduced fetal growth, but also for the development of asthma and possibly COPD later in life. Of note, recent evidence suggests that the disease risk can be transferred across generations, that is, from grandparents to their grandchildren. While initial studies in mouse models on in utero smoke exposure have provided important mechanistic insights, there are still knowledge gaps that need to be filled.

OBJECTIVE

Thus, in this review, we summarize current knowledge on this topic derived from mouse models, while also introducing two other relevant animal models: the fruit fly Drosophila melanogaster and the zebrafish Danio rerio.

METHODS

This review is based on an intensive review of PubMed-listed transgenerational animal studies from 1902 to 2018 and focuses in detail on selected literature due to space limitations.

RESULTS

This review gives a comprehensive overview of mechanistic insights obtained in studies with the three species, while highlighting the remaining knowledge gaps. We will further discuss potential (dis)advantages of all three animal models.

CONCLUSION/CLINICAL RELEVANCE

Many studies have already addressed transgenerational inheritance of disease risk in mouse, zebrafish or fly models. We here propose a novel strategy for how these three model organisms can be synergistically combined to achieve a more detailed understanding of in utero cigarette smoke-induced transgenerational inheritance of disease risk.

Interaction of Glutathione S-Transferase M1, T1, and P1 Genes With Early Life Tobacco Smoke Exposure on Lung Function in Adolescents

BACKGROUND

Glutathione S-transferase (GST) genes are involved in the management of oxidative stress in the lungs. We aimed to determine whether they modify the associations between early life smoke exposure and adverse lung health outcomes.

METHODS

The Melbourne Atopy Cohort study (a high-risk birth cohort) enrolled 620 children and followed them prospectively from birth. We recorded perinatal tobacco smoke exposure, asthma, and lung function at 12 (59%) and 18 years (66%) and genotyped for GSTM1, GSTT1, and GSTP1 (69%).

RESULTS

GST genotypes were found to interact with tobacco smoke exposure on lung function outcomes (P interaction ≤ .05). Only among children with GSTT1 null genotypes was exposure to mother's, father's, or parental tobacco smoke in early life associated with an increased risk of reductions in prebronchodilator (BD) FEV₁ and FVC at both 12 and 18 years. These associations were not seen in children with GSTT1 present. Similarly, only among children with GSTM1 null genotypes was exposure to father's or parental smoking associated with reductions in pre- and post-BD FEV₁ and FVC at 18 years. Only among children with Ile/Ile genotypes of GSTP1 was exposure to mother's smoking associated with increased risk of reduced FEV₁ at 18 years, but this was not the case among children with Val/Val or Ile/Val genotypes.

CONCLUSIONS

Our study provides evidence of interaction between early tobacco smoke exposure and GST genotypes on lung function. Carriers of GST null mutations and GSTP1 Ile/Ile alleles may be more susceptible when exposed to tobacco smoke in early life. These findings support stronger recommendations to protect all infants from tobacco smoke exposure.

TRIAL REGISTRY

Australian and New Zealand Clinical Trials Registry; No.: ACTRN12609000734268; URL: http://www.anzctr.org.au/.

Pollen exposure at birth and adolescent lung function, and modification by residential greenness

BACKGROUND

Exposure to high levels of pollen in infancy is a risk factor for allergic respiratory diseases in later childhood, but effects on lung function are not fully understood. We aim to examine associations between grass pollen exposure in the first months of life and lung function at 12 and 18 years, and explore potential modification.

METHODS

Using the Melbourne Atopy Cohort Study, a birth cohort of children with a family history of allergic diseases, we modeled the association between cumulative grass pollen exposure up to 3 months after birth, on FEV₁ , FVC, and FEV₁ /FVC ratio at 12 and 18 years. We also assessed modifying effects of residential greenness levels (derived from satellite imagery), asthma, and early life sensitization to ryegrass.

RESULTS

Grass pollen exposure in the first 7 days was associated with a reduction in FEV₁ (-15.5 mL; 95% CI: -27.6, -3.3 per doubling of pollen count) and FVC (-20.8 mL; -35.4, -6.1) at 12 years, but not at 18 years. Increase in cumulative grass pollen exposure up to 3 months was negatively associated with FVC at 12 and 18. Exposure to high residential greenness modified the association at 18 years.

CONCLUSION

Early exposure to grass pollen was associated with decreased lung function in children and adolescents. Targeted interventions for pollen avoidance strategies that take into account local topography could be implemented alongside other clinical interventions such as immunotherapy.

Assessing the impact of air pollution on childhood asthma morbidity: how, when, and what to do

PURPOSE OF REVIEW

Exposure to air pollutants is linked with poor asthma control in children and represents a potentially modifiable risk factor for impaired lung function, rescue medication use, and increased asthma-related healthcare utilization. Identification of the most relevant pollutants to asthma as well as susceptibility factors and strategies to reduce exposure are needed to improve child health.

RECENT FINDINGS

The current available literature supports the association between pollutants and negative asthma outcomes. Ethnicity, socioeconomic status, and presence of certain gene polymorphisms may impact susceptibility to the negative health effects of air pollution. Improved air quality standards were associated with better asthma outcomes.

SUMMARY

The link between air pollution and pediatric asthma morbidity is supported by the recent relevant literature. Continued efforts are needed to identify the most vulnerable populations and develop strategies to reduce exposures and improve air quality.

Smoking and lung function among adults with newly onset asthma

Introduction

Smoking increases the risk of asthma and reduces lung function among subjects with and without asthma. We assessed the effects of smoking on lung function reflecting both central and small airways among adults with newly onset asthma.

Methods

In a population-based study, 521 (response rate 86%) working-aged adults with clinically defined newly diagnosed asthma answered a questionnaire on personal smoking and other factors potentially influencing lung function, and performed spirometry. We applied multiple linear regression analysis to estimate the relations between smoking and lung function adjusting for confounding.

Results

Among asthmatics, FEV₁ level was reduced significantly, on average 208 mL, related to regular smoking (adjusted effect estimate −0.208, 95% CI −0.355 to −0.061) and 245 mL in relation to former smoking, that is, among those who quit less than a year ago (−0.245, 95% CI −0.485 to −0.004). In contrast, FEV₁ was not significantly related to occasional smoking or former smoking among those who quit over a year ago. Forced expiratory flow (FEF) levels (L/s) were also significantly reduced among regular smokers (FEF_25–75%: −0.372, 95% CI −0.607 to −0.137; FEF_50%: −0.476, 95% CI −0.750 to −0.202). An exposure–response pattern related to both daily smoking rate and lifetime cumulative smoking was seen both among men and women.

Conclusions

This study provides new evidence that among working-aged adults with new asthma, regular smoking and former smoking reduce lung function levels with a dose–response pattern. The lung function parameters applied as outcomes reflect both larger and smaller airways.

Using air-quality feedback to encourage disadvantaged parents to create a smoke-free home: Results from a randomised controlled trial

OBJECTIVE

To determine if low-cost air-quality monitors providing personalised feedback of household second-hand smoke (SHS) concentrations plus standard health service advice on SHS were more effective than standard advice in helping parents protect their child from SHS.

DESIGN

A randomised controlled trial of a personalised intervention delivered to disadvantaged mothers who were exposed to SHS at home. Changes in household concentrations of fine Particulate Matter (PM_2.5) were the primary outcome.

METHODS

Air-quality monitors measured household PM_2.5 concentrations over approximately 6 days at baseline and at one-month and six-months post-intervention. Data on smoking and smoking-rules were gathered. Participants were randomised to either Group A (standard health service advice on SHS) or Group B (standard advice plus personalised air-quality feedback). Group B participants received personalised air-quality feedback after the baseline measurement and at 1-month. Both groups received air-quality feedback at 6-months.

RESULTS

120 mothers were recruited of whom 117 were randomised. Follow up was completed after 1-month in 102 and at 6-months in 78 participants. There was no statistically significant reduction in PM_2.5 concentrations by either intervention type at 1-month or 6-months, nor significant differences between the two groups at 1-month (p = 0.76) and 6-month follow-up (p = 0.16).

CONCLUSIONS

Neither standard advice nor standard advice plus personalised air-quality feedback were effective in reducing PM_2.5 concentrations in deprived households where smoking occurred. Finding ways of identifying homes where air-quality feedback can be a useful tool to change household smoking behaviour is important to ensure resources are targeted successfully.

Tobacco smoke exposure in early life and adolescence in relation to lung function

Maternal smoking during pregnancy is associated with impaired lung function among young children, but less is known about long-term effects and the impact of adolescents' own smoking. We investigated the influence of maternal smoking during pregnancy, secondhand smoke exposure and adolescent smoking on lung function at age 16 years.

The BAMSE (Barn/Child, Allergy, Milieu, Stockholm, Epidemiology) birth cohort collected information on participants' tobacco smoke exposure through repeated questionnaires, and measured saliva cotinine concentrations at age 16 years. Participants performed spirometry and impulse oscillometry (IOS) at age 16 years (n=2295).

Exposure to maternal smoking during pregnancy was associated with reduced forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) ratio of −1.1% (95% CI −2.0 to −0.2%). IOS demonstrated greater resistance at 5–20 Hz (R_5–20) in participants exposed to maternal smoking during pregnancy. Adolescents who smoked had reduced FEV₁/FVC ratios of −0.9% (95% CI −1.8 to −0.1%) and increased resistance of 6.5 Pa·L^–1·s (95% CI 0.7 to 12.2 Pa·L^–1·s) in R_5–20. Comparable associations for FEV₁/FVC ratio were observed for cotinine concentrations, using ≥12 ng·mL⁻¹ as a cut-off for adolescent smoking.

Maternal smoking during pregnancy was associated with lower FEV₁/FVC ratios and increased airway resistance. In addition, adolescent smoking appears to be associated with reduced FEV₁/FVC ratios and increased peripheral airway resistance.

Maternal smoking in utero and teenage smoking are associated with indices of airway obstruction at age 16 yearshttp://ow.ly/NwF030jFS2W