Breastfeeding as a modifier of the respiratory effects of air pollution in children

Asthma and Other Respiratory Diseases of Children in Relation to Personal Behavior, Household, Parental and Environmental Factors in West China

Asthma and other respiratory diseases, which are of great concern in public health, are paid less attention in areas that are less economically developed. This research aimed to study the prevalence of critical respiratory diseases of children living in West China and figure out the potential influencing factors. A total of 575 children under the age of 14 were recruited from Xinjiang, China, to participate in the study in 2022. Information on activity patterns, socioeconomic and parental factors, and household and surrounding environment situations was obtained using a questionnaire survey. Logistic regression models were applied to estimate the odds ratios of respiratory disease prevalence in relation to behavior patterns, household, parental and environmental factors, respectively. The prevalence of ever doctor-diagnosed asthma, doctor-diagnosed bronchitis and current bronchitis were 4.7%, 19.0% and 14.4%, respectively. The prevalence of doctor-diagnosed pneumonia was 8.2%, which was two times higher in urban than rural areas. Longer annual heating duration was significantly associated with higher risks in children's asthma and bronchitis, with an odds ratio (OR) and 95% confidence interval (95% CI) of 3.363 (95% CI: 1.215-9.298) and 1.267 (95% CI: 1.002-1.601), respectively. Opening the window longer in autumn would lead to higher risks of bronchitis, with ORs of 1.165 and 1.133, respectively, for doctor-diagnosed bronchitis and current bronchitis. Residential air pollution and having a residence close to waste incineration plant or garbage station were, respectively, significantly associated with higher risks of doctor-diagnosed bronchitis and asthma. Parental disease history was associated with a higher prevalence of children's asthma and respiratory diseases, whereas breastfeeding and doing physical exercise were, respectively, significantly associated with a lower risk of asthma. A high prevalence of respiratory diseases in children in West China may be partly attributed to longer annual heating time, opening windows longer in autumn, surrounding environmental pollution, as well as parental disease history, whereas promoting physical activity and breastfeeding could be an effective measure to reduce the risk of childhood asthma in West China.

The association between childhood adiposity in northeast China and anthropogenic heat flux: A new insight into the comprehensive impact of human activities

Anthropogenic heat has been reported to have significant health impacts, but research on its association with childhood adiposity is still lacking. In this study, we matched the 2008-2012 average anthropogenic heat flux, as simulated by a grid estimation model using inventory methods, with questionnaire and measurement data of 49,938 children randomly recruited from seven cities in Northeast China in 2012. After adjusting for social demographic and behavioral factors, we used generalized linear mixed-effect models to assess the association between anthropogenic heat flux and adiposity among children. We also examined the effect modification of various social demographic and behavioral confounders. We found that each 10 W/m2 increase in total anthropogenic heat flux and that from the industry source was associated with an increase of 5.82% (95% CI = 0.84%-11.05%) and 6.62% (95% CI = 0.87%-12.70%) in the odds of childhood adiposity. Similarly, the excess rate of adiposity among children were 5.26% (95% CI = -1.33%-12.29%) and 8.51% (95% CI = 2.24%-15.17%) per 1 W/m2 increase in the anthropogenic heat flux from transportation and buildings, and was 7.94% (95% CI = 2.28%-13.91%) per 0.001 W/m2 increase in the anthropogenic heat flux from human metabolism. We also found generally greater effect estimates among female children and children who were exposed to passive smoking during pregnancy, born by caesarean section, non-breastfed/mixed-fed, or lived within 20 m adjacent to the main road. The potential deleterious effect of anthropogenic heat exposure on adiposity among children may make it a new but major threat to be targeted by future mitigation strategies.

Associations between air pollutant and pneumonia and asthma requiring hospitalization among children aged under 5 years in Ningbo, 2015-2017

Introduction

Exposure to ambient air pollutants is associated with an increased incidence of respiratory diseases such as pneumonia and asthma, especially in younger children. We investigated the relationship between rates of hospitalization of children aged under 5 years for pneumonia and asthma and the concentration of air pollutants in Ningbo between January 1, 2015 and August 29, 2017.

Methods

Data were obtained from the Ningbo Air Quality Data Real-time Publishing System and the big data platform of the Ningbo Health Information Center. A generalized additive model was established via logarithmic link function and utilized to evaluate the effect of pollutant concentration on lag dimension and perform sensitivity analysis.

Results

A total of 10,301 cases of pneumonia and 115 cases of asthma were identified over the course of this study. Results revealed that PM2.5, PM10, SO2 and NO2 were significantly associated with hospitalization for pneumonia and asthma in children under 5 years of age. For every 10-unit increase in lag03 air pollutant concentration, hospitalization for pneumonia and asthma due to PM2.5, PM10, SO2 and NO2 increased by 2.22% (95%CI: 0.64%, 3.82%), 1.94% (95%CI: 0.85%, 3.04%), 11.21% (95%CI: 4.70%, 18.10%) and 5.42% (95%CI: 3.07%, 7.82%), respectively.

Discussion

Adverse effects of air pollutants were found to be more severe in children aged 1 to 5 years and adverse effects due to PM2.5, PM10 and SO2 were found to be more severe in girls. Our findings underscore the need for implementation of effective public health measures to urgently improve air quality and reduce pediatric hospitalizations due to respiratory illness.

Association between long-term ambient ozone exposure and attention-deficit/hyperactivity disorder symptoms among Chinese children

BACKGROUND

Although ozone exposure has neurological toxicity, it remains unclear whether it was associated with an increased risk of attention-deficit/hyperactivity disorders (ADHD) among childhood.

METHODS

We matched the four-year average ozone concentration with questionnaire data for 35,103 children aged 3-12 years from seven cities in Liaoning, China, 2012-2013. Using mixed-effect logistic regression models, we assessed the association of ozone concentration with multiple ADHD indicators using the Conners Abbreviated Symptom Questionnaire (C-ASQ), including explicit attention-deficit/hyperactivity symptoms (ADHD; score ≥15), attention-deficit/hyperactivity disorder tendencies (ADHD-T; 11 ≤ score ≤14), and attention-deficit/hyperactivity problems (ADHP; score ≥11). Results were also stratified by sociodemongraphics.

RESULTS

After adjusting for covariates, we found that each interquartile range (IQR) increase in ozone concentration was associated with an increased risk of ADHD, ADHD-T, and ADHP (P < 0.001) with an odds ratio of 1.12 (95% confidence interval, 1.04-1.21), 1.08 (1.03-1.13), and 1.09 (1.05-1.14), respectively. Additionally, we found greater effect estimates in children who reported longer exercise time (vs those with limited exercise time) with odds ratio of 1.18 (1.07-1.31) vs 1.06 (0.96-1.17) for ADHD, 1.13 (1.06-1.21) vs 1.03 (0.96-1.10) for ADHD-T, and 1.15 (1.08-1.21) vs 1.04 (0.98-1.10) for ADHP. Non-breastfed children were also shown to be more vulnerable to ADHD with an odds ratio of 1.22 (1.09-1.36) compared with 1.06 (0.96-1.16) among the rest.

CONCLUSIONS

Long-term ozone exposure may be associated with increased ADHD among children. Additional studies are needed to validate our findings and support policies and interventions to address this growing public health concern.

Short-term effects of air pollution on respiratory diseases among young children in Wuhan city, China

BACKGROUND

The high risks for childhood respiratory diseases are associated with exposure to ambient air pollution. However, there are few studies that have explored the association between air pollution exposure and respiratory diseases among young children (particularly aged 0-2 years) based on the entire population in a megalopolis.

METHODS

Daily hospital admission records were obtained from 54 municipal hospitals in Wuhan city, China. We included all children (aged 0-2 years) hospitalized with respiratory diseases between January 2017 and December 2018. Individual air pollution exposure assessment was used in Land Use Regression model and inverse distance weighted. Case-crossover design and conditional logistic regression models were adopted to estimate the hospitalization risk associated with air pollutants.

RESULTS

We identified 62,425 hospitalizations due to respiratory diseases, of which 36,295 were pneumonia. Particulate matter with an aerodynamic diameter less than 2.5 μm (PM_2.5) and nitrogen dioxide (NO₂) were significantly associated with respiratory diseases and pneumonia. ORs of pneumonia were 1.0179 (95% CI 1.0097-1.0260) for PM_2.5 and 1.0131 (95% CI 1.0042-1.0220) for NO₂ at lag 0-7 days. Subgroup analysis suggested that NO₂, Ozone (O₃) and sulfur dioxide (SO₂) only showed effects on pneumonia hospitalizations on male patients, but PM_2.5 had effects on patients of both genders. Except O₃, all pollutants were strongly associated with pneumonia in cold season. In addition, children who aged elder months and who were in central urban areas had a higher hospitalization risk.

CONCLUSIONS

Air pollution is associated with higher hospitalization risk for respiratory diseases, especially pneumonia, among young children, and the risk is related to gender, month age, season and residential location.

Association between eye-level greenness and lung function in urban Chinese children

BACKGROUND

Health effects of greenness perceived by residents at eye level has received increasing attention. However, the associations between eye-level greenness and respiratory health are unknown. The aim of the study was to investigate the associations between exposure to eye-level greenness and lung function in children.

METHODS

From 2012 to 2013, a total of 6740 school children in seven cities in northeast China were recruited into this cross-sectional study. Forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), peak expiratory flow rate (PEF), and maximum mid expiratory flow rate (MMEF) were measured to evaluate lung function and to define lung impairment. Eye-level greenness was extracted from segmented Tencent Map street view images, and a corresponding green view index (GVI) was calculated. Higher GVIs mean more greenness coverage. Mixed-effects logistic regressions were used to estimate the health effects on lung impairment per interquartile range (IQR) increase in GVI. Linear regressions were used to estimate the associations between GVI and lung function. The health effects of ambient air pollutants were also assessed, including particulate matter with an aerodynamic diameter <1.0 μm (PM₁), <2.5 μm (PM_2.5), <10 μm (PM₁₀) as well as nitrogen dioxide (NO₂).

RESULTS

An increase of GVI_800m was associated with lung impairment in FEV₁, FVC, PEF and MMEF, with ORs ranging from 0.68 (95% CI: 0.59, 0.79) to 0.83 (95% CI: 0.74, 0.93). The associations between an IQR increase of GVI_800m and FEV₁ (48.15 ml, 95% CI: 30.33-65.97 ml), FVC (50.57 ml, 95% CI: 30.65-70.48 ml), PEF (149.59 ml/s, 95% CI: 109.79-189.38 ml/s), and MMEF (61.18 ml/s, 95% CI: 31.07-91.29 ml/s) were significant, and PM₁, PM_2.5, and PM₁₀ were found to be mediators of this relationship.

CONCLUSION

More eye-level greenness was associated with better lung function and reduced impairment. However, eye-level greenness associations with lung function became non-significant once lower particulate matter air pollution exposures were considered.

The Role of CD4+ T Cells and Microbiota in the Pathogenesis of Asthma

Asthma, a chronic respiratory disease involving variable airflow limitations, exhibits two phenotypes: eosinophilic and neutrophilic. The asthma phenotype must be considered because the prognosis and drug responsiveness of eosinophilic and neutrophilic asthma differ. CD4+ T cells are the main determinant of asthma phenotype. Th2, Th9 and Tfh cells mediate the development of eosinophilic asthma, whereas Th1 and Th17 cells mediate the development of neutrophilic asthma. Elucidating the biological roles of CD4+ T cells is thus essential for developing effective asthma treatments and predicting a patient's prognosis. Commensal bacteria also play a key role in the pathogenesis of asthma. Beneficial bacteria within the host act to suppress asthma, whereas harmful bacteria exacerbate asthma. Recent literature indicates that imbalances between beneficial and harmful bacteria affect the differentiation of CD4+ T cells, leading to the development of asthma. Correcting bacterial imbalances using probiotics reportedly improves asthma symptoms. In this review, we investigate the effects of crosstalk between the microbiota and CD4+ T cells on the development of asthma.

Associations between trees and grass presence with childhood asthma prevalence using deep learning image segmentation and a novel green view index

Limitations of Normalized Difference Vegetation Index (NDVI) potentially contributed to the inconsistent findings of greenspace exposure and childhood asthma. The aim of this study was to use a novel greenness exposure assessment method, capable of overcoming the limitation of NDVI to determine the extent to which it was associated with asthma prevalence in Chinese children. During 2009-2013, a cross-sectional study of 59,754 children aged 2-17 years was conducted in northeast China. Tencent street view images surrounding participants' schools were segmented by a deep learning model, and streetscape greenness was extracted. The green view index (GVI) was used to assign exposure and higher value indicates more green coverage. Mixed-effects logistic regression models were used to calculate the adjusted odds of asthma per interquartile range (IQR) increase of GVI for trees and grass. Participants were further stratified to investigate whether particulate matter with an aerodynamic diameter <2.5 μm (PM_2.5) was a modifier. An IQR increase in GVI_800m for trees was associated with lower adjusted odds of doctor-diagnosed asthma (OR: 0.76; 95%CI: 0.72-0.80) and current asthma (OR: 0.82; 95%CI: 0.75-0.89). An IQR increase in GVI_800m for grass was associated with higher adjusted odds of doctor-diagnosed asthma (OR: 1.04; 95%CI: 1.00-1.08) and current asthma (OR: 1.08; 95%CI: 1.02-1.14). After stratification by PM_2.5 exposure level, the negative association between trees and asthma, and the positive association between grass and asthma were observed only in low PM_2.5 exposure levels (≤median: 56.23 μg/m³). Our results suggest that types of vegetation may play a role in the association between greenness exposure and childhood asthma. Exposure to trees may reduce the odds of childhood asthma, whereas exposure to grass may increase the odds. Additionally, PM_2.5 may modify the associations of trees and grass with childhood asthma.

Relationships between Long-Term Ozone Exposure and Allergic Rhinitis and Bronchitic Symptoms in Chinese Children

Numerous studies have demonstrated that exposure to ambient ozone (O₃) could have adverse effects on children's respiratory health. However, previous studies mainly focused on asthma and wheezing. Evidence for allergic rhinitis and bronchitic symptoms (e.g., persistent cough and phlegm) associated with O₃ is limited, and results from existing studies are inconsistent. This study included a total of 59,754 children from the seven northeastern cities study (SNEC), who were aged 2 to 17 years and from 94 kindergarten, elementary and middle schools. Information on doctor-diagnosed allergic rhinitis (AR), persistent cough, and persistent phlegm was collected during 2012-2013 using a standardized questionnaire developed by the American Thoracic Society (ATS). Information for potential confounders was also collected via questionnaire. Individuals' exposure to ambient ozone (O₃) during the four years before the investigation was estimated using a satellite-based random forest model. A higher level of O₃ was significantly associated with increased risk of AR and bronchitic symptoms. After controlling for potential confounders, the OR (95% CI) were 1.13 (1.07-1.18), 1.10 (1.06-1.16), and 1.12 (1.05-1.20) for AR, persistent cough, and persistent phlegm, respectively, associated with each interquartile range (IQR) rise in O₃ concentration. Interaction analyses showed stronger adverse effects of O₃ on AR in children aged 7-17 years than those aged 2-6 years, while the adverse association of O₃ with cough was more prominent in females and children aged 7-12 years than in males and children aged 2-6 and 13-17 years. This study showed that long-term exposure to ambient O₃ was significantly associated with higher risk of AR and bronchitic symptoms in children, and the association varies across age and gender. Our findings contribute additional evidence for the importance of controlling O₃ pollution and protecting children from O₃ exposure.

Family Health Behavior: Preventive Measures against Acute Respiratory Infections in Under-5 Children

BACKGROUND

The under-5 mortality rate in Indonesia is 32 per 1,000 live births, still higher than the SDG target. Acute respiratory infections (ARIs), as one of the leading causes of death, must be prevented. Arguments emerge concerning the association of home crowding, health behavior, and the incidence of ARI.

METHODS

A cross-section analysis with the Indonesia Demographic and Health Survey (IDHS) 2017 dataset is performed. Samples are restricted to 16,555 children aged 0-59 months who lived with their mother (eligible women interviewed) during the survey. For each of the variables observed during this study, missing data must be omitted as exclusion criteria. A 100 per cent answer rate was achieved. Logistic regression was used to determine ARI-associated factors, by examining the effect of each explanatory factor (independent variables) on the odds ratio of ARI (one dependent binary variable).

RESULTS

The prevalence of ARI was more common among children living in the poorest households (AOR 1.66; 95% CI, 1.20 - 2.28) and those exposed to indoor tobacco smoke pollution (AOR 1.27; 95% CI, 1.04-1.56). On the other hand, those aged 0-5 months (AOR 0.59; 95% CI, 0.43-0.82), living at home with improved sanitation (AOR 0.74; 95% CI, 0.61-0.89), and exclusively breastfed (AOR 0.85; 95% CI, 0.73-0.99) were less likely to have ARI.

CONCLUSIONS

Home crowding is not associated with ARI. Efforts should be focused on preserving family health behavior. The family functioned as a health-support system for their under-5 children by establishing an indoor tobacco smoking-free zone, practicing exclusive breastfeeding, and enhancing hygiene facilities.

Ambient particulate matter (PM1, PM2.5, PM10) and childhood pneumonia: The smaller particle, the greater short-term impact?

BACKGROUND

Smaller sizes of ambient particulate matter (PM) can be more toxic and can be breathed into lower lobes of a lung. Children are particularly vulnerable to PM air pollution because of their adverse effects on both lung functions and lung development. However, it remains unknown whether a smaller PM has a greater short-term impact on childhood pneumonia.

AIMS

We compared the short-term effects on childhood pneumonia from PM with aerodynamic diameters ≤1 μm (PM₁), ≤2.5 μm (PM_2.5), and ≤10 μm (PM₁₀), respectively.

METHODS

Daily time-series data (2016-2018) on pneumonia hospitalizations in children aged 0-17 years, records of air pollution (PM₁, PM_2.5, PM₁₀, and gaseous pollutants), and weather conditions were obtained for Hefei, China. Effects of different PM were quantified using a quasi-Poisson generalized additive model after controlling for day of the week, holiday, seasonality and long-term time trend, and weather variables. Stratified analyses (gender, age, and season) were also performed.

RESULTS

For each 10 μg/m³ increase in PM₁, PM_2.5, and PM₁₀ concentrations over the past three days (lag 0-2), the risk of pneumonia hospitalizations increased by 10.28% (95%CI: 5.88%-14.87%), 1.21% (95%CI: 0.34%-2.09%), and 1.10% (95%CI: 0.44%-1.76%), respectively. Additionally, both boys and girls were at risk of PM₁ effects, while PM_2.5 and PM₁₀ effects were only seen in boys. Children aged ≤12 months and 1-4 years were affected by PM₁, but PM_2.5 and PM₁₀ were only associated with children aged 1-4 years. Furthermore, PM₁ effects were greater in autumn and winter, while greater PM_2.5 and PM₁₀ effects were evident only in autumn.

CONCLUSION

This study suggests a greater short-term impact on childhood pneumonia from PM₁ in comparison to PM_2.5 and PM₁₀. Given the serious PM pollution in China and other rapid developing countries due to various combustions and emissions, more investigations are needed to determine the impact of different PM on childhood respiratory health.

Current pet ownership modifies the adverse association between long-term ambient air pollution exposure and childhood asthma

BACKGROUND

Recent studies suggest that household endotoxin and allergens can modify the impact of air pollutants on development of asthma; however, epidemiological evidence is limited and conflicting.

OBJECTIVES

To investigate whether pet ownership modified the association between ambient air pollution and asthma in children.

METHODS

We conducted a population-based cross-sectional study, the Seven Northeast Cities Study in China and recruited a total of 59,754 children from 94 schools during 2012-2013. Long-term air pollutant concentrations, including airborne particulate matter with a diameter of 1 μm or less (PM₁ ), PM_2.5 , PM₁₀ , and nitrogen dioxide (NO₂ ) from 2009 to 2012 were estimated using a random forest model. We collected information of respiratory health in children using the Epidemiologic Standardization Project Questionnaire of the American Thoracic Society (ATS-DLD-78-A). Regression models were used to evaluate associations between pet ownership and air pollution on asthma after adjusting for potential covariates.

RESULTS

Exposure to increasing levels of air pollutants was associated with higher prevalence of asthma, but associations were significantly attenuated in children who owned pets. For example, compared to children without pets, those who owned pets did not have an increased risk of symptoms of asthma (odds ratio, 1.01, 95% confidence interval: 0.78, 1.30), wheeze (0.96, 95% confidence interval [CI]: 0.76, 1.21), and cough (1.01, 95% CI: 0.87, 1.18) for each 10 µg/m³ increase in PM₁ (P_-int  < 0.05). Similar trends were observed for other air pollutants. Dog and bird ownership decreased the associations of asthma and cough with air pollutant exposure. The main findings were consistent with a series of sensitivity analyses.

CONCLUSION

Current pet ownership may reduce the adverse impact of long-term air pollution on childhood asthma. Longitudinal studies are needed to confirm this finding which could have important implications for public health.

Early-life exposure to submicron particulate air pollution in relation to asthma development in Chinese preschool children

BACKGROUND

Emerging research suggested an association of early-life particulate air pollution exposure with development of asthma in childhood. However, the potentially differential effects of submicron particulate matter (PM; PM with aerodynamic diameter ≤1 μm [PM₁]) remain largely unknown.

OBJECTIVE

This study primarily aimed to investigate associations of childhood asthma and wheezing with in utero and first-year exposures to size-specific particles.

METHODS

We conducted a large cross-sectional survey among 5788 preschool children aged 3 to 5 years in central China. In utero and first-year exposures to ambient PM₁, PM with aerodynamic diameter less than or equal to 2.5 μm, and PM with aerodynamic diameter less than or equal to 10 μm at 1 × 1-km resolution were assessed using machine learning-based spatiotemporal models. A time-to-event analysis was performed to examine associations between residential PM exposures and childhood onset of asthma and wheezing.

RESULTS

Early-life size-specific PM exposures, particularly during pregnancy, were significantly associated with increased risk of asthma, whereas no evident PM-wheezing associations were observed. Each 10-μg/m³ increase in in utero and first-year PM₁ exposure was accordingly associated with an asthma's hazard ratio in childhood of 1.618 (95% CI, 1.159-2.258; P = .005) and 1.543 (0.822-2.896; P = .177). Subgroup analyses suggest that short breast-feeding duration may aggravate PM-associated risk of childhood asthma. Each 10-μg/m³ increase in in utero exposure to PM₁, for instance, was associated with a hazard ratio of 2.260 (1.393-3.666) among children with 0 to 5 months' breast-feeding and 1.156 (0.721-1.853) among those longer breast-fed.

CONCLUSIONS

Our study added comparative evidence for increased risk of childhood asthma in relation to early-life PM exposures, highlighting stronger associations with ambient PM₁ than with PM with aerodynamic diameter less than or equal to 2.5 μm and PM with aerodynamic diameter less than or equal to 10 μm.

Air pollution during infancy and lung function development into adolescence: The GINIplus/LISA birth cohorts study

BACKGROUND

Limited evidence exists on how air pollution exposure during infancy, i.e. the first year of life, may affect lung function development into adolescence.

OBJECTIVES

To investigate the association between exposure to air pollution during the first-year of life and lung function development up to the age of 15 in Germany.

METHODS

We investigated 915 children from the GINIplus and LISA birth cohorts from Munich (n = 181) and Wesel (n = 734), who had at least two spirometric measurements at ages 6, 10 and 15. Z-scores of forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) were calculated. Annual average concentrations of nitrogen dioxide, particulate matter with diameters <2.5, <10 and 2.5-10 µm (PM_{2.5/10/coarse}), and PM_2.5 absorbance at home addresses during the first-year of life, were estimated by land-use regression models. Associations between infancy exposure and lung function changes were fitted using multivariable linear mixed models with adjustment for potential confounders.

RESULTS

For per interquartile range increase in air pollutants during the first-year life, FEV₁ z-scores declined annually by -0.012 (95% confidence interval (CI): -0.014, -0.009) for PM_2.5 to -0.023 (95%CI: -0.028, -0.018) for PM_coarse. The declines in FVC were lower than FEV₁ [-0.006 (95%CI: -0.008, -0.003) to -0.011 (95%CI: -0.019, -0.003)]. In Munich, the attenuations were only significant for FEV₁. Effect estimates of infancy exposure for certain air pollutants were higher for groups with asthma, older maternal age, and breastfeeding <12 weeks than their counterparts.

DISCUSSION

Infancy exposure to higher air pollution may reduce lung function development up to adolescence, with airway size more affected than lung volume restriction. The potential modifying effects of maternal age, asthmatic status of children and breastfeeding warrant further exploration.

Modification of caesarean section on the associations between air pollution and childhood asthma in seven Chinese cities

It is unknown whether giving birth via caesarean section (c-section) is a modifier for the association between air pollution and asthma. From 2012 to 2013, 59,754 children between the ages of 2 and 17 were randomly selected from 94 middle schools, elementary schools and kindergartens in seven Chinese cities for a cross-sectional study. The children's parents or guardians completed questionnaires, from which data on asthma as well as asthma-related symptoms were obtained. Participants' exposure to particles with an aerodynamic diameter ≤1.0 μm (PM₁), ≤2.5 μm (PM_2.5), and ≤10 μm (PM₁₀) and exposure to nitrogen dioxide (NO₂) were estimated using random forest models. We used mixed effects logistic regression models and added an interaction term between mode of delivery and ambient air pollution into the model to estimate effect modification from c-sections after appropriate adjustments for potential confounding variables. Among children delivered by c-section, the adjusted ORs for asthma and its symptoms per interquartile range (IQR) increase of PM₁, PM_2.5, PM₁₀ and NO₂ (1.20 95% CI: 1.07-1.34 to 2.04 95% CI: 1.87-2.24) were significantly higher than those of children delivered vaginally (1.05 95% CI: 0.92-1.19 to 1.33 95%CI: 1.21-1.47). The interactions between c-sections and ambient air pollution were statistically significant for all studied respiratory disorders, except current wheeze. Delivery via c-section may increase the risks of air pollution on asthma and its symptoms in Chinese children.

Is PM1 similar to PM2.5? A new insight into the association of PM1 and PM2.5 with children's lung function

Experimental data suggests that PM₁ is more toxic than PM_2.5 although the epidemiologic evidence suggests that the health associations are similar. However, few objective exposure data are available to compare the associations of PM₁ and PM_2.5 with children lung function. Our objectives are a) to evaluate associations between long-term exposure to PM₁, PM_2.5 and children's lung function, and b) to compare the associations between PM₁ and PM_2.5. From 2012 to 2013, we enrolled 6,740 children (7-14 years), randomly recruited from primary and middle schools located in seven cities in northeast China. We measured lung function including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), and maximal mid-expiratory flow (MMEF) utilizing two portable electronic spirometers. We dichotomized continuous lung function measures according the expected values for gender and age. The spatial resolution at which PM₁ and PM_2.5 estimated were estimated using a machine learning method and the temporal average concentrations were averaged from 2009 to 2012. A multilevel regression model was used to estimate the associations of PM₁, PM_2.5 exposure and lung function measures, adjusted for confounding factors. Associations with lower lung function were consistently larger for PM₁ than for PM_2.5. Adjusted odds ratios (OR) per interquartile range greater PM₁ ranged from 1.53 for MMEF (95% confidence interval [CI]: 1.20-1.96) to 2.14 for FEV1 (95% CI: 1.66-2.76) and ORs for PM_2.5 ranged from 1.36 for MMEF (95%CI: 1.12-1.66) to 1.82 for FEV1 (95%CI: 1.49-2.22), respectively. PM₁ and PM_2.5 had significant associations with FVC and FEV1 in primary school children, and on PEF and MMEF in middle school children. Long-term PM₁ and PM_2.5 exposure can lead to decreased lung function in children, and the associations of PM₁ are stronger than PM_2.5. Therefore, PM₁ may be more hazardous to children's respiratory health than PM_2.5 exposure.

Household air pollution and under-five mortality in sub-Saharan Africa: an analysis of 14 demographic and health surveys

BACKGROUND

Globally, over four million deaths are attributed to exposure to household air pollution (HAP) annually. Evidence of the association between exposure to HAP and under-five mortality in sub-Saharan Africa (SSA) is insufficient. We assessed the association between exposure to HAP and under-five mortality risk in 14 SSA countries.

METHODS

We pooled Demographic and Health Survey (DHS) data from 14 SSA countries (N = 164376) collected between 2015 and 2018. We defined exposure to HAP as the use of biomass fuel for cooking in the household. Under-five mortality was defined as deaths before age five. Data were analyzed using mixed effects logistic regression models.

RESULTS

Of the study population, 73% were exposed to HAP and under-five mortality was observed in 5%. HAP exposure was associated with under-five mortality, adjusted odds ratio (OR) 1.33 (95% confidence interval (CI) [1.03-1.71]). Children from households who cooked inside the home had higher risk of under-five mortality compared to households that cooked in separate buildings [0.85 (0.73-0.98)] or outside [0.75 (0.64-0.87)]. Lower risk of under-five mortality was also observed in breastfed children [0.09 (0.05-0.18)] compared to non-breastfed children.

CONCLUSIONS

HAP exposure may be associated with an increased risk of under-five mortality in sub-Saharan Africa. More carefully designed longitudinal studies are required to contribute to these findings. In addition, awareness campaigns on the effects of HAP exposure and interventions to reduce the use of biomass fuels are required in SSA.

Furry pet-related wheeze and rhinitis in pre-school children across China: Associations with early life dampness and mould, furry pet keeping, outdoor temperature, PM10 and PM2.5

BACKGROUND

Few Chinese population studies exist on early life risk factors for furry pet allergy.

OBJECTIVES

We studied childhood respiratory symptoms when in contact with furry pets in relation to early life exposure. Moreover, we studied similar environmental associations for rhinitis not related to furry pets.

METHODS

Children aged 3-6 y from day care centres in seven Chinese cities participated (N = 39,782). Parents answered a questionnaire on home environment and children's health, including rhinoconjunctivitis and wheeze when in contact with furry pets, and diagnosed rhinitis. Prenatal and postnatal outdoor temperature, PM_2.5, PM₁₀, and NO₂ were calculated using data from monitoring stations. Associations were estimated by multilevel logistic regression.

RESULTS

Totally 2% had cats, 4% dogs, and 3.2% had rhinoconjunctivitis or wheeze when in contact with furry pets (FP symptoms). Moreover, 1.1% had furry pet related diagnosed rhinitis and 7.5% had diagnosed rhinitis not related to furry pets (other diagnosed rhinitis). Prenatal PM_2.5 and PM₁₀, especially in second trimester, and a colder climate were risk factors for FP symptoms. ETS, dampness and mould, condensation on windows in wintertime, and cats and dog keeping were associated with FP symptoms. Breast feeding and frequent window opening were protective. Similar indoor associations were found for furry pet related diagnosed rhinitis. ETS, dampness and mould, window condensation, urbanization and mechanical exhaust ventilation were risk factors for other diagnosed rhinitis. Cooking with an electric stove and early life exposure to animals (cats, dogs, farm environment during pregnancy) were protective for diagnosed rhinitis not related to furry pets.

CONCLUSIONS

Prenatal outdoor PM₁₀ and PM_2.5 can be risk factors for symptoms suggestive of furry pet allergy. Early life dampness and mould can be risk factors for rhinitis related and not related to furry pets. Exposure to animals (cats, dogs, farm environment) may reduce diagnosed rhinitis not related to furry pets.

Greenness surrounding schools is associated with lower risk of asthma in schoolchildren

BACKGROUND

There is increasing interest in the effect of residential greenness on respiratory health in children with inconsistent results. However, there are no studies investigating the association between greenness around schools, a representative environment for children and childhood asthma.

OBJECTIVES

To investigate the association between greenness surrounding schools and asthma in schoolchildren.

METHODS

We recruited 59,754 schoolchildren from 94 schools in 2012-2013 from the Seven Northeast Cities Study, China. Greenness surrounding schools was measured using the normalized difference vegetation index (NDVI) and soil adjusted vegetation index (SAVI) at buffers from 30 to 1000 m. Asthma symptoms were collected from validated self-reported questionnaires. Logistic mixed-effects regression models were used to estimate the associations between greenness surrounding school and childhood asthma after adjustment for covariates.

RESULTS

We found that greenness surrounding schools in all buffered sizes was negatively associated with the prevalence of asthmatic symptoms in schoolchildren. A 0.1-unit increase in NDVI_1000m was associated with lower odds of current asthma (odds ratio: 0.81, 95% confidential interval: 0.75, 0.86) and current wheeze (OR: 0.89, 95% CI: 0.84, 0.94) in children after covariate adjustments. Higher greenness was associated with less asthma symptoms in a dose-response pattern (P for trend < 0.05). The estimated associations appeared to be stronger in children exposure to higher air pollution level. The observed associations varied across seven cities.

CONCLUSION

Our findings suggest beneficial associations of greenness surrounding schools with childhood asthma. Further studies are needed to confirm our results.

Changes in children's asthma prevalence over two decades in Lanzhou: effects of socioeconomic, parental and household factors

Background

The prevalence of childhood asthma may have changed with rapid economic development. This study aims to ascertain potential changes in asthma prevalence in relation to changes in socioeconomic, parental and household factors, based on a comparison between two periods spanning over 20 years in Lanzhou, a large northwestern city of China.

Methods

Cross-sectional studies using the same protocols were performed in Lanzhou, China in 1994–1995 (Period I) and in 2017 (Period II). Children of 6–12 years old from elementary schools were selected by a multistage sampling method. Information on the presence of asthma and asthma-related symptoms of children, socioeconomic status, feeding methods, parental illness and behavior patterns, as well as household characteristics, were collected through a questionnaire survey. Logistic regression models were used to estimate odds ratios of asthma prevalence with regard to socioeconomic, parental and household factors, respectively.

Results

Significant prevalence reductions were observed for paternal smoking, household coal use, and parental asthma, while the prevalence increased significantly for children sleeping in their own rooms or own beds, ventilation use during cooking, and parental occupation and education level after 22 years. In children, the prevalence of ever-diagnosed asthma decreased from 3.2% in period I to 1.5% in Period II (P<0.001); the prevalence of wheeze also decreased from 15.4% to 9.3% (P<0.001). Passive smoking (OR =1.531, 95% CI: 1.032–2.270) and poor household ventilation (OR =1.709, 95% CI: 1.208–2.416) were significantly associated with an increased prevalence of wheeze in Period I, whereas household mold (OR =2.112, 95% CI: 1.203–3.811) was significantly associated with prevalence of wheeze. Parental asthma history was associated with increased prevalence of asthma and asthma-related symptoms. Breastfeeding was significantly associated with reduced risk of asthma in period II children.

Conclusions

The prevalence of asthma and that of asthma-related symptoms were lower in 2017 than in 1994–1995 in school children living in Lanzhou. In 2017 with increased urbanization and industrialization, breastfeeding became a significant protective factor and household mold was a significant risk factor for asthma diagnosis and asthma-related symptoms. Promoting breastfeeding and household mold control is recommended to reduce the risk of childhood asthma in contemporary Lanzhou.

Coal burning-derived SO2 and traffic-derived NO2 are associated with persistent cough and current wheezing symptoms among schoolchildren in Ulaanbaatar, Mongolia

Background

Children in Ulaanbaatar are exposed to air pollution, but few epidemiological studies have been conducted on the effects of environmental risk factors on children’s health. Also, no studies have yet examined the prevalence of respiratory symptoms in children in suburban areas, where air quality-monitoring stations have not yet been installed. This cross-sectional study evaluated the associations between outdoor air pollution and respiratory symptoms among schoolchildren in urban and suburban districts of Ulaanbaatar.

Methods

The ATS-DLD-78 C questionnaire was used to investigate the respiratory symptoms of schoolchildren aged 6–12 years (n = 1190) who lived in one of three urban districts or a suburban district of Ulaanbaatar. In each district, the outdoor concentrations of nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) were measured at two sites (at ≤100 m and > 100 m from the nearest major road) in the 2-year period from 2015 to 2016. The associations between health outcomes and exposure to air pollutants were estimated using the multinomial logistic regression method.

Results

The outdoor concentration of SO₂ was significantly associated with persistent cough symptom (OR = 1.12, 95% CI 1.04–1.22). Furthermore, the outdoor concentration of NO₂ was significantly associated with the current wheezing symptom (OR = 1.33, 95% CI 1.01–1.75) among children in urban and suburban.

Conclusions

The prevalence of persistent cough symptom was markedly high among the schoolchildren in urban/suburban districts of Ulaanbaatar. Overall, the increases in the prevalence of respiratory symptoms among children might be associated with ambient air pollution in Ulaanbaatar.

Protective Effect of Breastfeeding on the Adverse Health Effects Induced by Air Pollution: Current Evidence and Possible Mechanisms

Air pollution is a major social, economic, and health problem around the world. Children are particularly susceptible to the negative effects of air pollution due to their immaturity and excessive growth and development. The aims of this narrative review were to: (1) summarize evidence about the protective effects of breastfeeding on the adverse health effects of air pollution exposure, (2) define and describe the potential mechanisms underlying the protective effects of breastfeeding, and (3) examine the potential effects of air pollution on breastmilk composition and lactation. A literature search was conducted using electronic databases. Existing evidence suggests that breastfeeding has a protective effect on adverse outcomes of indoor and outdoor air pollution exposure in respiratory (infections, lung function, asthma symptoms) and immune (allergic, nervous and cardiovascular) systems, as well as under-five mortality in both developing and developed countries. However, some studies reported no protective effect of breastfeeding or even negative effects of breastfeeding for under-five mortality. Several possible mechanisms of the breastfeeding protective effect were proposed, including the beneficial influence of breastfeeding on immune, respiratory, and nervous systems, which are related to the immunomodulatory, anti-inflammatory, anti-oxidant, and neuroprotective properties of breastmilk. Breastmilk components responsible for its protective effect against air pollutants exposure may be long chain polyunsaturated fatty acids (LC PUFA), antioxidant vitamins, carotenoids, flavonoids, immunoglobins, and cytokines, some of which have concentrations that are diet-dependent. However, maternal exposure to air pollution is related to increased breastmilk concentrations of pollutants (e.g., Polycyclic aromatic hydrocarbons (PAHs) or heavy metals in particulate matter (PM)). Nonetheless, environmental studies have confirmed that breastmilk’s protective effects outweigh its potential health risk to the infant. Mothers should be encouraged and supported to breastfeed their infants due to its unique health benefits, as well as its limited ecological footprint, which is associated with decreased waste production and the emission of pollutants.

Association of Breastfeeding and Air Pollution Exposure With Lung Function in Chinese Children

IMPORTANCE

Breastfeeding and exposure to ambient air pollutants have been found to be independently associated with respiratory health in children; however, previous studies have not examined the association of breastfeeding as a potential moderator of the association.

OBJECTIVE

To assess associations of breastfeeding and air pollution with lung function in children.

DESIGN, SETTING, AND PARTICIPANTS

Using a cross-sectional study design, children were recruited from 62 elementary and middle schools located in 7 Chinese cities from April 1, 2012, to October 31, 2013. Data analyses were conducted from November 1, 2018, to March 31, 2019.

EXPOSURES

Long-term concentrations of airborne particulate matter with a diameter of 1 μm or less (PM1), airborne particulate matter with a diameter of 2.5 μm or less (PM2.5), airborne particulate matter with a diameter of 10 μm or less (PM10), and nitrogen dioxide were estimated using a spatial statistical model matched to children's geocoded home addresses, and concentrations of PM10, sulfur dioxide, nitrogen dioxide, and ozone were measured by local air monitoring stations.

MAIN OUTCOMES AND MEASURES

Breastfeeding was defined as maternal report of having mainly breastfed for longer than 3 months. Lung function was measured using portable electronic spirometers. Using previously published predicted spirometric values for children in Northeast China as the reference, lung impairment was defined as forced vital capacity (FVC) less than 85%, forced expiratory volume in the first second of expiration less than 85%, peak expiratory flow less than 75%, or maximum midexpiratory flow less than 75%.

RESULTS

Participants included 6740 children (mean [SD] age, 11.6 [2.1] years; 3382 boys [50.2%]). There were 4751 children (70.5%) who were breastfed. Mean (SD) particulate matter concentrations ranged from 46.8 (6.5) μg/m3 for PM1 to 95.6 (9.8) μg/m3 for PM10. The prevalence of lung function impairment ranged from 6.8% for peak expiratory flow to 11.3% for FVC. After controlling for age, sex, and other covariates, 1-interquartile range greater concentration of pollutants was associated with higher adjusted odds ratios (AORs) for lung function impairment by FVC among children who were not breastfed compared with those who were (PM1: AOR, 2.71 [95% CI, 2.02-3.63] vs 1.20 [95% CI, 0.97-1.48]; PM2.5: AOR, 2.27 [95% CI, 1.79-2.88] vs 1.26 [95% CI, 1.04-1.51]; and PM10: AOR, 1.93 [95% CI, 1.58-2.37] vs 1.46 [95% CI, 1.23-1.73]). Younger age (<12 years) was associated with lower lung function impairment among the children who had been breastfed. In children from elementary schools, 1-interquartile range greater concentration of pollutants was associated with higher AORs for lung function impairment by FVC among children who had not been breastfed compared with those who had (PM1: AOR, 6.43 [95% CI, 3.97-10.44] vs 1.89 [95% CI, 1.28-2.80]; PM2.5: AOR, 3.83 [95% CI, 2.63-5.58] vs 1.50 [95% CI, 1.12-2.01]; and PM10: AOR, 2.61 [95% CI, 1.90-3.57] vs 1.52 [95% CI, 1.19-1.95]). Results from linear regression models also showed associations of air pollution with worse lung function among children who were not breastfed compared with their counterparts who were breastfed, especially for FVC (PM1: β, -240.46 [95% CI, -288.71 to -192.21] vs -38.21 [95% CI, -69.27 to -7.16] mL) and forced expiratory volume in the first second of expiration (PM1: β, -201.37 [95% CI, -242.08 to -160.65] vs -30.30 [95% CI, -57.66 to -2.94] mL).

CONCLUSIONS AND RELEVANCE

In this study, breastfeeding was associated with lower risk of lung function impairment among children in China exposed to air pollution, particularly among younger children.

Is smaller worse? New insights about associations of PM1 and respiratory health in children and adolescents

BACKGROUND AND OBJECTIVES

Little is known about PM₁ effects on respiratory health, relative to larger size fractions (PM_2.5). To address this literature gap, we assessed associations between PM₁ exposure and asthmatic symptoms in Chinese children and adolescents, compared with PM_2.5.

METHODS

A total of 59,754 children, aged 2-17 years, were recruited from 94 kindergartens, elementary and middle schools in the Seven Northeast Cities (SNEC) study, during 2012-2013. We obtained information on asthma and asthma-related symptoms including wheeze, persistent phlegm, and persistent cough using a standardized questionnaire developed by the American Thoracic Society. PM₁ and PM_2.5 concentrations were estimated using a spatial statistical model matched to the children's geocoded home addresses. To examine the associations, mixed models with school/kindergarten as random intercept were used, controlling for covariates.

RESULTS

Odds ratios (ORs) of doctor-diagnosed asthma associated with a 10-μg/m³ increase for PM₁ and PM_2.5 were 1.56 (95% CI: 1.46-1.66) and 1.50 (1.41-1.59), respectively, and similar pattern were observed for other outcomes. Interaction analyses indicated that boys and the individuals with an allergic predisposition may be vulnerable subgroups. For example, among children with allergic predisposition, the ORs for doctor diagnosed asthma per 10 μg/m³ increase in PM₁ was 1.71 (95% CI: 1.60-1.83), which was stronger than in their counterparts (1.46; 1.37-1.56) (p_{for interaction} < 0.05).

CONCLUSIONS

This study indicated that long-term exposure to PM₁ may increase the risk of asthma and asthma-related symptoms, especially among boys and those with allergic predisposition. Furthermore, these positive associations for PM₁ were very similar to those for PM_2.5.

Breastfeeding and the Developmental Origins of Asthma: Current Evidence, Possible Mechanisms, and Future Research Priorities

Breastfeeding has many established health benefits, but its impact on asthma development is uncertain. Breastfeeding appears to have a positive and dose-dependent impact on respiratory health, particularly during early childhood and in high-risk populations; however, the strength and causality of these associations are unclear. It is challenging to compare results across studies due to methodological differences and biological variation. Resolving these inconsistencies will require well-designed, prospective studies that accurately capture asthma diagnoses and infant feeding exposures (including breastfeeding duration, exclusivity, and method of feeding), account for key confounders, evaluate dose effects, and consider effect modification and reverse causality. Mechanistic studies examining human milk bioactives and their impact on lung health and asthma development are beginning to emerge, and these will be important in establishing the causality and mechanistic basis of the observed associations between breastfeeding and asthma. In this review, we summarize current evidence on this topic, identify possible reasons for disagreement across studies, discuss potential mechanisms for a causal association, and provide recommendations for future research.

Pet exposure in utero and postnatal decreases the effects of air pollutants on hypertension in children: A large population based cohort study

The effect of ambient air pollution exposure on childhood hypertension has emerged as a concern in China, and previous studies suggested pet ownership is associated with lower blood pressure (BP). However, limited information exists on the interactive effects pet ownership and air pollution exposure has on hypertension. We investigated the interactions between exposure to pet ownership and air pollutants on hypertension in Chinese children. 9354 students in twenty-four elementary and middle schools (aged 5-17 years) in Northeastern China were evaluated during 2012-2013. Four-year average concentrations of particulate matter with aerodynamic diameter of ≤10 μm (PM₁₀), SO₂, NO₂, and O₃, were collected in the 24 districts from 2009 to 2012. Hypertension was defined as average diastolic or systolic BP (three time measurements) in the 95th percentile or higher based on height, age, and sex. To examine effects, two-level regression analysis was used, controlling covariates. Consistent interactions between exposure to pet and air pollutants were observed. Compared to children exposed to pet, those not exposed exhibited consistently stronger effects of air pollution. The highest odds ratios (ORs) per 30.6 μg/m³ increase in PM₁₀ were 1.79 (95%confidence interval [95%CI]: 1.29-2.50) in children without current pet exposure compared to 1.24 (95%CI: 0.85-1.82) in children with current pet exposure. As for BP, only O₃ had an interaction for all exposure to pet ownership types, and showed lower BP in children exposed to pet. The increases in mean diastolic BP per 46.3 μg/m³ increase in O₃ were 0.60  mmHg (95%CI: 0.21, 0.48) in children without pet exposure in utero compared with 0.34  mmHg (95%CI: 0.21, 0.48) in their counterparts. When stratified by age, pet exposure was more protective among younger children. In conclusion, in this large population-based cohort, pet ownership is associated with smaller associations between air pollution and hypertension in children, suggesting pet ownership reduces susceptibility to the health effects of pollutants.

The effects of PM2.5 on asthmatic and allergic diseases or symptoms in preschool children of six Chinese cities, based on China, Children, Homes and Health (CCHH) project

The urbanization and industrialization in China is accompanied by bad air quality, and the prevalence of asthma in Chinese children has been increasing in recent years. To investigate the associations between ambient PM_2.5 levels and asthmatic and allergic diseases or symptoms in preschool children in China, we assigned PM_2.5 exposure data from the Global Burden of Disease (GBD) project to 205 kindergartens at a spatial resolution of 0.1° × 0.1° in six cities in China (Shanghai, Nanjing, Chongqing, Changsha, Urumqi, and Taiyuan). A hierarchical multiple logistical regression model was applied to analyze the associations between kindergarten-level PM_2.5 exposure and individual-level outcomes of asthmatic and allergic symptoms. The individual-level variables, including gender, age, family history of asthma and allergic diseases, breastfeeding, parental smoking, indoor dampness, interior decoration pollution, household annual income, and city-level variable-annual temperature were adjusted. A total of 30,759 children (average age 4.6 years, 51.7% boys) were enrolled in this study. Apart from family history, indoor dampness, and decoration as predominant risk factors, we found that an increase of 10 μg/m³ of the annual PM_2.5 was positively associated with the prevalence of allergic rhinitis by an odds ratio (OR) of 1.20 (95% confidence interval [CI] 1.11, 1.29) and diagnosed asthma by OR of 1.10 (95% CI 1.03, 1.18). Those who lived in non-urban (vs. urban) areas were exposed to more severe indoor air pollution arising from biomass combustion and had significantly higher ORs between PM_2.5 and allergic rhinitis and current rhinitis. Our study suggested that long-term exposure to PM_2.5 might increase the risks of asthmatic and allergic diseases or symptoms in preschool children in China. Compared to those living in urban areas, children living in suburban or rural areas had a higher risk of PM_2.5 exposure.

The Prebiotic and Probiotic Properties of Human Milk: Implications for Infant Immune Development and Pediatric Asthma

The incidence of pediatric asthma has increased substantially in recent decades, reaching a worldwide prevalence of 14%. This rapid increase may be attributed to the loss of "Old Friend" microbes from the human microbiota resulting in a less diverse and "dysbiotic" gut microbiota, which fails to optimally stimulate immune development during infancy. This hypothesis is supported by observations that the gut microbiota is different in infants who develop asthma later in life compared to those who remain healthy. Thus, early life exposures that influence gut microbiota play a crucial role in asthma development. Breastfeeding is one such exposure; it is generally considered protective against pediatric asthma, although conflicting results have been reported, potentially due to variations in milk composition between individuals and across populations. Human milk oligosaccharides (HMOs) and milk microbiota are two major milk components that influence the infant gut microbiota and hence, development of the immune system. Among their many immunomodulatory functions, HMOs exert a selective pressure within the infant gut microbial niche, preferentially promoting the proliferation of specific bacteria including Bifidobacteria. Milk is also a source of viable bacteria originating from the maternal gut and infant oral cavity. As such, breastmilk has prebiotic and probiotic properties that can modulate two of the main forces controlling the gut microbial community assembly, i.e., dispersal and selection. Here, we review the latest evidence, mechanisms and hypotheses for the synergistic and/or additive effects of milk microbiota and HMOs in protecting against pediatric asthma.

Prenatal Exposure to Traffic Pollution and Childhood Body Mass Index Trajectory

Background: Limited evidence suggests an association between prenatal exposure to traffic pollution and greater adiposity in childhood, but the time window during which growth may be most affected is not known. Methods: We studied 1,649 children in Project Viva, a Boston-area pre-birth cohort. We used spatiotemporal models to estimate prenatal residential air pollution exposures and geographic information systems to estimate neighborhood traffic density and roadway proximity. We used weight and stature measurements at clinical and research visits to estimate a BMI trajectory for each child with mixed-effects natural cubic spline models. In primary analyses, we examined associations of residential PM_2.5 and black carbon (BC) exposures during the third trimester and neighborhood traffic density and home roadway proximity at birth address with (1) estimated BMI at 6 month intervals through 10 years of age, (2) magnitude and timing of BMI peak and rebound, and (3) overall BMI trajectory. In secondary analyses, we examined associations of residential PM_2.5 and BC exposures during the first and second trimesters with BMI outcomes. Results: Median (interquartile range; IQR) concentration of residential air pollution during the third trimester was 11.4 (1.7) μg/m³ for PM_2.5 and 0.7 (0.3) μg/m³ for BC. Participants had a median (IQR) of 13 (7) clinical or research BMI measures from 0 to 10 years of age. None of the traffic pollution exposures were significantly associated with any of the BMI outcomes in covariate-adjusted models, although effect estimates were in the hypothesized direction for neighborhood traffic density and home roadway proximity. For example, greater neighborhood traffic density [median (IQR) 857 (1,452) vehicles/day x km of road within 100 m of residential address at delivery] was associated with a higher BMI throughout childhood, with the strongest associations in early childhood [e.g., per IQR increment natural log-transformed neighborhood traffic density, BMI at 12 months of age was 0.05 (-0.03, 0.13) kg/m² higher and infancy peak BMI was 0.05 (-0.03, 0.14) kg/m² higher]. Conclusions: We found no evidence for a persistent effect of prenatal exposure to traffic pollution on BMI trajectory from birth through mid-childhood in a population exposed to modest levels of air pollution.

Pre-natal and post-natal exposure to pet ownership and lung function in children: The Seven Northeastern Cities Study

To evaluate the association between pre-natal and post-natal exposure to pet ownership and lung function in children, a cross-sectional study named Seven Northeastern Cities (SNEC) study was conducted. In this study, children's lung function including the forced expiratory volume in 1 second (FEV₁ ), forced vital capacity (FVC), maximal mid-expiratory flow (MMEF), and peak expiratory flow (PEF) were measured by spirometers, and pet ownership situations were collected by questionnaire. Analyzed by multiple logistic regression and generalized linear modeling, we found that for all subjects, pet exposure in the first 2 years of life was significantly associated with lung function impairment of FVC<85% predicted (adjusted odds ratio [aOR]=1.28; 95% confidence interval [CI]: 1.01, 1.63). For current pet exposure, the increased odds of lung function impairment ranged from 35% (aOR=1.35; 95%CI: 1.12, 1.62) for FVC<85% predicted to 57% (aOR=1.57; 95%CI: 1.29, 1.93) for FEV₁ <85% predicted. The in utero exposure was not related to lung function impairment. Compared with other pets, higher odds were observed among children with dogs. When stratified by gender, girls with current pet exposure were more likely to have lung function impairment than boys. It implies self-reported exposures to pets were negatively associated with lung function among the children under study.

Short-term exposure to high ambient air pollution increases airway inflammation and respiratory symptoms in chronic obstructive pulmonary disease patients in Beijing, China

BACKGROUND

Few studies have investigated the short-term respiratory effects of ambient air pollution in chronic obstructive pulmonary disease (COPD) patients in the context of high pollution levels in Asian cities.

METHODS

A panel of 23 stable COPD patients was repeatedly measured for biomarkers of airway inflammation including exhaled nitric oxide (FeNO) and exhaled hydrogen sulfide (FeH2S) (215 measurements) and recorded for daily respiratory symptoms (794person-days) in two study periods in Beijing, China in January-September 2014. Daily ambient air pollution data were obtained from nearby central air-monitoring stations. Mixed-effects models were used to estimate the associations between exposures and health measurements with adjustment for potential confounders including temperature and relative humidity.

RESULTS

Increasing levels of air pollutants were associated with significant increases in both FeNO and FeH2S. Interquartile range (IQR) increases in PM2.5 (76.5μg/m(3), 5-day), PM10 (75.0μg/m(3), 5-day) and SO2 (45.7μg/m(3), 6-day) were associated with maximum increases in FeNO of 13.6% (95% CI: 4.8%, 23.2%), 9.2% (95% CI: 2.1%, 16.8%) and 34.2% (95% CI: 17.3%, 53.4%), respectively; and the same IQR increases in PM2.5 (6-day), PM10 (6-day) and SO2 (7-day) were associated with maximum increases in FeH2S of 11.4% (95% CI: 4.6%, 18.6%), 7.8% (95% CI: 2.3%, 13.7%) and 18.1% (95% CI: 5.5%, 32.2%), respectively. Increasing levels of air pollutants were also associated with increased odds ratios of sore throat, cough, sputum, wheeze and dyspnea.

CONCLUSIONS

FeH2S may serve as a novel biomarker to detect adverse respiratory effects of air pollution. Our results provide potential important public health implications that ambient air pollution may pose risk to respiratory health in the context of high pollution levels in densely-populated cities in the developing world.

Breastfeeding modifies the effects of environment tobacco smoke exposure on respiratory diseases and symptoms in Chinese children: the Seven Northeast Cities Study

To evaluate the potential effect of interaction between breastfeeding and environmental tobacco smoke (ETS) exposure on respiratory health, we studied 31 049 children (aged 2-14 years) from 25 districts of seven cities in northeast China. Parents of the children completed standardized questionnaires that characterized the children's histories of respiratory symptoms and illness, feeding methods, ETS exposure, and other associated risk factors. Breastfeeding was defined as having been mainly breastfed for 3 months or more. The results showed that the association of ETS exposure with childhood respiratory conditions/diseases was modified by breastfeeding, and the association for nonbreastfed children was stronger than that for breastfed children. In particular, for nonbreastfed children, the odds ratios (ORs) for the effect of current ETS exposure asthma was 1.71 (95% CI: 1.43-2.05); however, the OR for breastfed children was 1.33 (95% CI: 1.20-1.48), indicating that the interactions between breastfeeding and current ETS exposure on asthma were statistically significant (P = 0.019). When stratified by school (kindergarten vs. elementary school), breastfeeding was more protective for asthma-related symptoms among children from kindergarten. In conclusion, this study shows that breastfeeding is associated with smaller associations between ETS exposure and respiratory conditions in children, suggesting that breastfeeding reduces susceptibility to the respiratory effects of ETS.

Effects of Breastfeeding on Respiratory Symptoms in Infancy

OBJECTIVE

To assess the impact of potential risk factors on the development of respiratory symptoms and their specific modification by breastfeeding in infants in the first year of life.

STUDY DESIGN

We prospectively studied 436 healthy term infants from the Bern-Basel Infant Lung Development cohort. The breastfeeding status, and incidence and severity of respiratory symptoms (score) were assessed weekly by telephone interview during the first year of life. Risk factors (eg, pre- and postnatal smoking exposure, mode of delivery, gestational age, maternal atopy, and number of older siblings) were obtained using standardized questionnaires. Weekly measurements of particulate matter <10 μg were provided by local monitoring stations. The associations were investigated using generalized additive mixed model with quasi Poisson distribution.

RESULTS

Breastfeeding reduced the incidence and severity of the respiratory symptom score mainly in the first 27 weeks of life (risk ratio 0.70; 95% CI 0.55-0.88). We found a protective effect of breastfeeding in girls but not in boys. During the first 27 weeks of life, breastfeeding attenuated the effects of maternal smoking during pregnancy, gestational age, and cesarean delivery on respiratory symptoms. There was no evidence for an interaction between breastfeeding and maternal atopy, number of older siblings, child care attendance, or particulate matter <10 μg.

CONCLUSIONS

This study shows the risk-specific effect of breastfeeding on respiratory symptoms in early life using the comprehensive time-series approach.

Health benefits from improved outdoor air quality and intervention in China

China is at its most critical stage of outdoor air quality management. In order to prevent further deterioration of air quality and to protect human health, the Chinese government has made a series of attempts to reduce ambient air pollution. Unlike previous literature reviews on the widespread hazards of air pollution on health, this review article firstly summarized the existing evidence of human health benefits from intermittently improved outdoor air quality and intervention in China. Contents of this paper provide concrete and direct clue that improvement in outdoor air quality generates various health benefits in China, and confirm from a new perspective that it is worthwhile for China to shift its development strategy from economic growth to environmental economic sustainability. Greater emphasis on sustainable environment design, consistently strict regulatory enforcement, and specific monitoring actions should be regarded in China to decrease the health risks and to avoid long-term environmental threats.

Interactions Between Air Pollution and Obesity on Blood Pressure and Hypertension in Chinese Children

BACKGROUND

Little information exists regarding the effect of interaction of obesity and long-term air pollution exposure on children's blood pressure and hypertension in areas with high levels of air pollution. The aim of this study is to assess effect modification by obesity on the association between exposure and blood pressure in Chinese children.

METHODS

We studied 9,354 Chinese children, ages 5-17 years old, from 24 elementary schools and 24 middle schools in the Seven Northeastern Cities during 2012-2013. Four-year average concentrations of particles with an aerodynamic diameter ≤10 µm (PM10), sulfur dioxide, nitrogen dioxides, and ozone (O3) were measured at the monitoring stations in the 24 districts. We used generalized additive models and two-level logistic regression models to examine the health effects.

RESULTS

Consistent interactions were found between exposure and obesity on blood pressure and hypertension. The association between exposure and hypertension was consistently larger for overweight/obese children than for children with normal-weight, with odds ratios for hypertension ranging from 1.16 per 46.3μg/m for O3 (95% confidence interval [CI] = 1.12, 1.20) to 2.91 per 30.6μg/m for PM10 (95% CI = 2.32, 3.64), and estimated increases in mean systolic and diastolic blood pressure ranging from 0.57 mmHg (95% CI = 0.36, 0.78) and 0.63 mmHg (95% CI = 0.46, 0.81) per 46.3 μg/m for O3 to 4.04 mmHg (95% CI = 3.00, 5.09) and 2.02 mmHg (95% CI = 1.14, 2.89) per 23.4 μg/m for sulfur dioxide.

CONCLUSIONS

Obesity amplifies the association of long-term air pollution exposure with blood pressure and hypertension in Chinese children.

Gender- and age-specific risk factors for wheeze from birth through adolescence

BACKGROUND AND OBJECTIVE

Cross-sectional gender differences in wheeze are well documented, but few studies have examined the gender-specific risk factors for wheeze longitudinally. This study aims to identify gender- and age-specific risk factors for wheeze from birth through adolescence.

METHODS

The incidence of wheeze was ascertained every 6 months through age 14 years in a birth cohort consisting of 499 children with a parental history of atopy. Gender- and age-specific risk factors were identified through generalized estimating equations.

RESULTS

A total of 454 (91.0%) and 351 (70.3%) children were followed past age 7 and 13 years, respectively. Maternal asthma was a risk factor for wheeze in girls (OR = 2.05, 95% CI 1.44-2.91, P < 0.0001) and boys (OR = 1.79, 1.29-2.48, P = 0.0004) and had a similar effect on wheeze throughout the ages. Paternal asthma (OR = 1.83, 1.38-2.57, P = 0.0005) and infant bronchiolitis (OR = 2.15, 1.47-3.14, P < 0.0001) were risk factors for boys only, with similar effects throughout the ages.

CONCLUSION

Using a prospective cohort, we identified gender- and age-specific risk factors for wheeze. The identification of gender-specific early life risk factors may allow for timely interventions and a more personalized approach to the treatment of asthma.

Changing childhood malnutrition in Bangladesh: trends over the last two decades in urban–rural differentials (1993–2012)

Objective

The present study determined trends in malnutrition among under-5 children in urban and rural areas of Bangladesh.

Design

Surveillance.

Setting

The study was conducted in the urban Dhaka and the rural Matlab hospitals of the International Centre for Diarrhoeal Disease Research, Bangladesh, where every fiftieth patient and all patients coming from the Health and Demographic Surveillance System were enrolled.

Subjects

A total of 28 816 under-5 children were enrolled at Dhaka from 1993 to 2012 and 11 533 at Matlab between 2000 and 2012.

Results

In Dhaka, 46 % of the children were underweight, 39 % were stunted and 28 % were wasted. In Matlab, the corresponding figures were 39 %, 31 % and 26 %, respectively. At Dhaka, 0·5 % of the children were overweight and obese when assessed by weight-for-age Z-score >+2·00, 1·4 % by BMI-for-age Z-score >+2·00 and 1·4 % by weight-for-height Z-score >+2·00; in Matlab the corresponding figures were 0·5 %, 1·4 % and 1·4 %, respectively. In Dhaka, the proportion of underweight, stunting and wasting decreased from 59 % to 28 % (a 53 % reduction), from 54 % to 22 % (59 % reduction) and from 33 % to 21 % (36 % reduction), respectively, between 1993 and 2012. In Matlab, these indicators decreased from 51 % to 27 % (a 47 % reduction), from 36 % to 25 % (31 % reduction) and from 34 % to 14 % (59 % reduction), respectively, from 2000 to 2012. On the other hand, the proportion of overweight (as assessed by BMI-for-age Z-score) increased significantly over the study period in both Dhaka (from 0·6 % to 2·6 %) and Matlab (from 0·8 % to 2·2 %).

Conclusions

The proportion of malnourished under-5 children has decreased gradually in both urban and rural Bangladesh; however, the reduction rates are not in line with meeting Millennium Development Goal 1. Trends for increasing childhood obesity have been noted during the study period as well.

Air pollution associated hypertension and increased blood pressure may be reduced by breastfeeding in Chinese children: the Seven Northeastern Cities Chinese Children's Study

BACKGROUND

Little is known about the association between air pollution and hypertension among children, and no studies report whether breastfeeding modifies this association in children.

METHODS

Nine thousand three hundred fifty-four Chinese children, ages 5-17 years old, from 24 elementary schools and 24 middle schools in the Seven Northeastern Cities during 2012-2013 were evaluated. The weight, height, and BP were measured. Four-year average concentrations of particles with an aerodynamic diameter of ≤10 μm (PM10), sulfur dioxide (SO2), nitrogen dioxides (NO2), ozone (O3), and carbon monoxide (CO) were calculated from monitoring stations. Two-level regression analysis was used to examine the effects, controlling for covariates.

RESULTS

The results showed that associations existed between hypertension and pollutants. The odds ratios for hypertension ranged from 1.12 per 46.3 μg/m3 increase for O3 (95% confidence interval [CI], 1.10-1.13) to 1.68 per 30.6 μg/m3 increase for PM10 (95% CI, 1.53-1.86). The increases in mean diastolic BP ranged from 0.58 mm Hg per 46.3 μg/m3 increase for O3 (95% CI, 0.52-0.63 mm Hg) to 2.89 mm Hg per 563.4 μg/m3 increase for CO (95% CI: 2.53-3.24 mm Hg). The increase in systolic BP ranged from 0.50 mm Hg per 46.3 μg/m3 increase for O3 (95% CI: 0.43-0.57 mm Hg) to 2.10 mm Hg per 30.6 μg/m3 increase for PM10 (95% CI, 1.73-2.47 mm Hg). Compared with children who had been breastfed, non-breastfed children exhibited consistently stronger effects.

CONCLUSION

Study findings indicate that high levels of PM10, SO2, NO2, O3, and CO are associated with increased arterial BP and hypertension among the children. Breastfeeding may reduce the risk.

Prevention of asthma: where are we in the 21st century?

Asthma is the most common chronic disease of childhood and, in the latter part of the 20th century, reached epidemic proportions. Asthma is generally believed to result from gene-environment interactions. There is consensus that a 'window of opportunity' exists during pregnancy and early in life when environmental factors may influence its development. We review multiple environmental, biologic and sociologic factors that may be important in the development of asthma. Meta-analyses of studies have demonstrated that multifaceted interventions are required in order to develop asthma prevention. Multifaceted allergen reduction studies have shown clinical benefits. Asthma represents a dysfunctional interaction with our genes and the environment to which they are exposed, especially in fetal and early infant life. The increasing prevalence of asthma also may be an indication of increased population risk for the development of other chronic non-communicable autoimmune diseases. This review will focus on the factors which may be important in the primary prevention of asthma. Better understanding of the complex gene-environment interactions involved in the development of asthma will provide insight into personalized interventions for asthma prevention.

Residential characteristics and household risk factors and respiratory diseases in Chinese women: the Seven Northeast Cities (SNEC) study

BACKGROUND

Few studies have assessed the impact of residential home characteristics and home environmental risk factors on respiratory diseases in Chinese women. Therefore, this study sought to determine the association between residential home features, domestic pets, home renovation and other indoor environmental risk factors with respiratory health outcomes of Chinese women.

METHODS

This cross-sectional study included a study sample of 30,780 Chinese women aged 23 to 49 from 25 districts of seven cities in Liaoning Province, Northeast China. Information on respiratory health, residential characteristics, and indoor air pollution sources was obtained by a standard questionnaire from the American Thoracic Society. Multivariable logistic regression was used to estimate prevalence odds ratios (POR) and 95% confidence interval (95%CI).

RESULTS

The odds of respiratory diseases were higher for those who lived near the main road, or near ambient air pollution sources. Pet-keeping was associated with increased odds of chronic bronchitis (POR=1.40; 95%CI: 1.09-1.81) and doctor-diagnosed asthma (POR=2.07; 95%CI: 1.18-3.64). Additionally, humidifier use was associated with increased odds of chronic bronchitis (POR=1.44; 95%CI: 1.07-1.94). Home renovation in recent 2 years was associated with increased likelihood of allergic rhinitis (POR=1.39; 95%CI 1.17-1.64).

CONCLUSION

Home renovation and residential home environmental risk factors were associated with an increased likelihood of respiratory morbidity among Chinese women.