Gender differences and effect of air pollution on asthma in children with and without allergic predisposition: northeast Chinese children health study

Chlorinated paraffins in particulate matter associated with asthma and its relative symptoms in school-aged children and adolescents: A cross-sectional survey in South China

Particulate matter (PM) and contaminants attached to PM can increase the risk of respiratory diseases. However, the health risk assessment of chlorinated paraffins (CPs), an emerging pollutant occupying a high proportion of persistent organic pollutants (POPs) in PM, remains scarce. This study aimed to evaluate the association between PM2.5-bound CPs and asthma, along with relative symptoms, in school-aged children and adolescents. A large sample size cross-sectional study (n = 131,304) was conducted in the Pearl River Delta (PRD). The results showed that increased quantiles of ∑CPs were associated with odds ratios (ORs) of 1.22 (95%CI: 1.20-1.25), 1.38 (95%CI: 1.35-1.41), 1.17 (95%CI: 1.15-1.19), 1.52 (95%CI: 1.48-1.56), 1.66 (95%CI: 1.61-1.71), and 1.33 (95%CI: 1.30-1.37) for ever diagnosed asthma, current asthma, wheeze, current wheeze, persistent phlegm, and persistent cough, respectively. Additionally, C11-, C12-SCCPs and C14-, C17-MCCPs contributed the most positive weight to the risk of asthma and relative symptoms. These findings provide cutting-edged evidence for the health risk assessment of CPs, which is crucial for developing effective CPs management strategy.

The Relationship Between PM2.5 and Eight Common Lung Diseases: A Two-Sample Mendelian Randomization Analysis

Air pollutants have both acute and chronic impacts on human health, affecting multiple systems and organs. While PM2.5 exposure is commonly assumed to be strongly associated with all respiratory diseases, this relationship has not been systematically analyzed. This study employed a two-sample Mendelian randomization approach to investigate the effects of PM2.5 on eight common lung diseases, using data from GWAS. Additionally, multivariable Mendelian randomization was applied to assess the direct effects of various air pollutants and the mediating roles of common factors such as BMI and smoking. At a significance threshold of 5×10-8, PM2.5 showed a significant causal relationship with both asthma and COPD. When the screening threshold was relaxed to 5× 10-6, this exposure continued to demonstrate significant associations not only with asthma and COPD, but also with other respiratory diseases, including pneumonia, emphysema/chronic bronchitis, and lung cancer. In the multivariable Mendelian randomization analysis, which controlled for smoking and bacterial infections, the association with pneumonia became non-significant, while the relationships with the other four diseases persisted. This study provides a systematic exploration of the relationship between PM2.5 and eight pulmonary diseases from a new perspective, deepening our understanding of the impact of air pollution on health and laying the foundation for future efforts to mitigate these effects.

Chinese expert consensus on the diagnosis, treatment, and management of asthma in women across life

Background

The epidemiology and severity of asthma vary by sex and age. The diagnosis, treatment, and management of asthma in female patients are quite challenging. However, there is hitherto no comprehensive and standardized guidance for female patients with asthma.

Methods

Corresponding search strategies were determined based on clinical concerns regarding female asthma. Search terms included "sex hormones and lung development", "sex hormone changes and asthma", "hormones and asthma immune response", "women, asthma", "children, asthma", "puberty, asthma", "menstruation, asthma", "pregnancy, asthma", "lactation, asthma", "menopause, asthma", "obesity, asthma", and "women, refractory, severe asthma". Literature was retrieved from PubMed/Medline, Embase, Cochrane Library, China Biology Medicine disc, China National Knowledge Infrastructure, Wanfang Data with the search date of July 30, 2022 as the last day. This consensus used the Grading of Recommendations Assessment, Development, and Evaluation to evaluate the strength of recommendation and quality of evidence.

Results

We collected basic research results and clinical evidence-based medical data and reviewed the effects of sex hormones, classical genetics, and epigenetics on the clinical presentation and treatment response of female patients with asthma under different environmental effects. Based on that, we formulated this expert consensus on the management of female asthma throughout the life cycle.

Conclusions

This expert consensus on the management of asthma in women throughout the life cycle provides diagnosis, treatment, and research reference for clinical and basic medical practitioners.

Associations of particulate matter, gaseous pollutants, and road traffic noise with the prevalence of asthma in children

The purposes of this study were to elucidate the associations between exposure to particulate matter, gaseous pollutants, and road traffic noise and asthma prevalence and to determine the interaction between exposure to multiple pollutants and asthma in children. A total of 3,246 children were recruited from 11 kindergartens in New Taipei City, Taiwan. Land use regression (LUR) was used to establish predictive models for estimating individual exposure levels of particulate matter, gaseous pollutants, and the 24 h A-weighted equivalent sound pressure level (LAeq,24). Multiple logistic regression was performed to test the associations between exposure to these environmental factors and asthma prevalence in children. Multiple-exposure models revealed that an interquartile-range (IQR) increase in PM2.5 (1.17 μg/m3) and PM10 (10.69 μg/m3) caused a 1.34-fold (95% confidence interval [CI] = 1.05-1.70) and 1.17-fold (95% CI = 1.01-1.36) increase in risk of asthma prevalence in children after adjusting for LAeq,24 and NO2. Co-exposure to PM2.5, LAeq,24, and O3, SO2, or CO, as well as co-exposure to PM10, LAeq,24, and CO produced similar findings. Only exposure to one IQR of SO2 (0.15 ppb) was observed a significant association (odds ratio = 1.16, 95% CI = 1.00-1.34) with the asthma prevalence in children after adjusting for PM10 and LAeq,24. Exposure to PM2.5, PM10, and SO2 may be associated with a higher asthma prevalence in children, while other gaseous pollutants and road traffic noise did not demonstrate significant associations. The interaction of exposure to air pollutants and road traffic noise on asthma prevalence in children was not observed in this study.

Ozone Pollution and Acute Exacerbation of Asthma in Residents of China: An Ecological Study

Purpose

The evidence for a causal relationship between high-level ozone (O3) exposure and acute exacerbation of asthma among adults is limited, and the conclusions are less definitive.

Patients and methods

Here we collected the daily data on asthma cases, O3 exposure, and meteorological factors from 2010 to 2016 in Shijiazhuang, China. We investigated the risk of asthma exacerbation associated with high-level ozone exposure using a polynomial distributed lag model (PDLM). Using a generalized additive model (GAM), we estimated the interactive effects between O3 and other pollutants as well as meteorological factors on asthma exacerbation.

Results

A total of 7270 patients with asthma were enrolled from 22 governmental hospitals in 13 counties. Each 10 μg/m3 increase in O3 concentration on the exacerbation of asthma was associated with a 1.92% (95% CI = 0.80-3.03%) higher risk of asthma exacerbation on day lag 7. The cumulative risk of O3 on asthma exacerbation increased by 18.9% (95% CI = 12.8-25.4%) on the 14th day. High consecutive levels of O3 increase the risk of asthma exacerbation, and the interactive effect of O3 and sulfur dioxide (SO2) appears before the exacerbation onset.

Conclusion

These findings suggested that O3 should be an important risk factor for asthma exacerbation, and health benefits in reducing asthma exacerbation risk would be gained with continued efforts to improve the air quality in China.

Role of Air Pollution in the Development of Asthma Among Children with a History of Bronchiolitis in Infancy

BACKGROUND

Infants experiencing bronchiolitis are at increased risk for asthma, but few studies have identified modifiable risk factors. We assessed whether early life air pollution influenced child asthma and wheeze at age 4-6 years among children with a history of bronchiolitis in the first postnatal year.

METHODS

Children with caregiver-reported physician-diagnosed bronchiolitis were drawn from ECHO-PATHWAYS, a pooled longitudinal cohort from six US cities. We estimated their air pollution exposure from age 1 to 3 years from validated spatiotemporal models of fine particulate matter (PM 2.5 ), nitrogen dioxide (NO 2 ), and ozone (O 3 ). Caregivers reported children's current wheeze and asthma at age 4-6 years. We used modified Poisson regression to estimate relative risks (RR) and 95% confidence intervals (CI), adjusting for child, maternal, and home environmental factors. We assessed effect modification by child sex and maternal history of asthma with interaction models.

RESULTS

A total of 224 children had caregiver-reported bronchiolitis. Median (interquartile range) 2-year pollutant concentrations were 9.3 (7.8-9.9) µg/m 3 PM 2.5 , 8.5 (6.4-9.9) ppb NO 2 , and 26.6 (25.6-27.7) ppb O 3 . RRs (CI) for current wheeze per 2-ppb higher O 3 were 1.3 (1.0-1.7) and 1.4 (1.1-1.8) for asthma. NO 2 was inversely associated with wheeze and asthma whereas associations with PM 2.5 were null. We observed interactions between NO 2 and PM 2.5 and maternal history of asthma, with lower risks observed among children with a maternal history of asthma.

CONCLUSION

Our results are consistent with the hypothesis that exposure to modest postnatal O 3 concentrations increases the risk of asthma and wheeze among the vulnerable subpopulation of infants experiencing bronchiolitis.

Chronic exposure to ambient PM2.5/NO2 and respiratory health in school children: A prospective cohort study in Hong Kong

Despite increasing concerns about the detrimental effects of air pollution on respiratory health, limited evidence is available on these effects in the Hong Kong population, especially in children. In this prospective cohort study between 2012 and 2017, we aimed to investigate the associations between exposure to air pollution (concentrations of fine particulate matter [PM_2.5] and nitrogen dioxide [NO₂]) and respiratory health (lung function parameters and respiratory diseases and symptoms) in schoolchildren. We recruited 5612 schoolchildren aged 6-16 years in Hong Kong. We estimated the annual average concentrations of ambient PM_2.5 and NO₂ at each participant's address using spatiotemporal models. We conducted spirometry tests on all participants to measure their lung function parameters and used a self-administered questionnaire to collect information on their respiratory diseases and symptoms and a wide range of covariates. Linear mixed models were used to investigate the associations between exposure to air pollution and lung function. Mixed-effects logistic regression models with random effects were used to investigate the associations of exposure to air pollution with respiratory diseases and symptoms. In all of the participants, every 5-μg/m³ increase in the ambient PM_2.5 concentration was associated with changes of - 13.90 ml (95 % confidence interval [CI]: -23.65 ml, -4.10 ml), - 4.20 ml (-15.60 ml, 7.15 ml), 27.20 ml/s (-3.95 ml/s, 58.35 ml/s), and - 19.80 ml/s (-38.35 ml/s, -1.25 ml/s) in forced expiratory volume in 1 s, forced vital capacity, peak expiratory flow, and maximal mid-expiratory flow, respectively. The corresponding lung function estimates for every 5-μg/m³ increase in the ambient NO₂ concentration were - 2.70 ml (-6.05 ml, 0.60 ml), - 1.40 ml (-5.40 ml, 2.60 ml), - 6.60 ml/s (-19.75 ml/s, 6.55 ml/s), and - 3.05 ml/s (-11.10 ml/s, 5.00 ml/s), respectively. We did not observe significant associations between PM_2.5/NO₂ exposure and most respiratory diseases and symptoms. Stratified analyses by sex and age showed that the associations between exposure to air pollution and lung function parameters were stronger in male participants and older participants (11-14 year old group) than in female participants and younger participants (6-10 year old group), respectively. Our results suggest that chronic exposure to air pollution is detrimental to the respiratory health of schoolchildren, especially that of older boys. Our findings reinforce the importance of air pollution mitigation to protect schoolchildren's respiratory health.

Association of Ambient Air Pollution with Blood Pressure in Adolescence: A Systematic-review and Meta-analysis

We systematically reviewed the association of ambient air pollution with blood pressure (BP) as a primary outcome in adolescents (10-19 years). Five databases (Ovid Medline, Ovid Embase, Web of Science, The Cochrane Library, and LILACS) were searched for relevant articles published up to August 2022. Meta-analyses were conducted using STATA v17 (Protocol - OSF Registries https://doi.org/10.17605/OSF.IO/96G5Q). Eight studies (5 cohort, 3 cross-sectional) with approximately 15,000 adolescents were included. Data from 6 studies were suitable for inclusion in the meta-analyses. In sub-group analyses, non-significant positive associations were observed for cohort studies assessing long-term exposure to PM10, PM2.5, and NO2 on systolic and diastolic BP. At age 12 years old (3702 adolescents), we found significant positive associations for long-term exposure to PM2.5(β=5.33 (1.56, 9.09) mmHg) and PM10 (β=2.47 (0.10, 4.85) mmHg) on diastolic BP. Significant positive associations were observed (3,592 adolescents) for long-term exposure to PM10(β=0.34 (0.19, 0.50) mmHg) and NO2 on diastolic BP (β=0.40 (0.09, 0.71) mmHg), and PM10 on systolic BP (β=0.48 (0.19, 0.77) mmHg). The overall quality of evidence analysed was graded as "low/very low." Insufficient data for short-term exposures to PM2.5, PM10, NO2, CO on BP led to their exclusion from the meta-analysis. Inconsistent associations were reported for gender-stratified results. The evidence, though of low-quality and limited, indicated that ambient air pollution was positively associated with adolescent BP. Future studies need improved measures of air pollutant exposures, consideration of gender and socio-economic circumstances on the observed pollution effects, as well as adjustment for other potential confounding factors.

Health effects of exposure to sulfur dioxide, nitrogen dioxide, ozone, and carbon monoxide between 1980 and 2019: A systematic review and meta-analysis

The burden of disease attributed to the indoor exposure to sulfur dioxide (SO₂ ), nitrogen dioxide (NO₂ ), ozone (O₃ ), and carbon monoxide (CO) is not clear, and the quantitative concentration-response relationship is a prerequisite. This is a systematic review to summarize the quantitative concentration-response relationships by screening and analyzing the polled effects of population-based epidemiological studies. After collecting literature published between 1980 and 2019, a total of 19 health outcomes in 101 studies with 182 health risk estimates were recruited. By meta-analysis, the leave-one-out sensitivity analysis and Egger's test for publication bias, the robust and reliable effects were found for SO₂ (per 10 μg/m³ ) with chronic obstructive pulmonary diseases (COPD) (pooled relative risks [RRs] 1.016, 95% CI: 1.012-1.021) and cardiovascular diseases (CVD) (RR 1.012, 95%CI: 007-1.018), respectively. NO₂ (per 10 μg/m³ ) had the pooled RRs for childhood asthma, preterm birth, lung cancer, diabetes, and COPD by 1.134 (1.084-1.186), 1.079 (1.007-1.157), 1.055 (1.010-1.101), 1.019 (1.009-1.029), and 1.016 (1.012-1.120), respectively. CO (per 1 mg/m³ ) was significantly associated with Parkinson's disease (RR 1.574, 95% CI: 1.069-2.317) and CVD (RR 1.024, 95% CI: 1.011-1.038). No robust effects were observed for O₃ . This study provided evidence and basis for further estimation of the health burden attributable to the four gaseous pollutants.

Children's exposure to air pollution in a natural gas industrial area and their risk of hospital admission for respiratory diseases

The rapid expansion of the natural gas industry to meet the global demand have raised environmental health concerns. Few studies have found that areas with natural gas industrial activity have poor air quality. However, the negative health impacts of ambient air pollution in a natural gas industrial area remain unclear. This study aimed to explore the relationship between short-term exposure to air pollution and hospital admissions for respiratory diseases among children in a natural gas industrial area in Bintulu, Malaysia. Daily hospital admissions for respiratory diseases among children were collected from a hospital in Bintulu from 2010 to 2019. Data on six air pollutants (PM₁₀, PM_2.5, SO₂, NO₂, O₃, and CO) in the study area were obtained from the Department of Environment Malaysia. Quasi-Poisson time series regressions with distributed lag non-linear models (DLNM) were applied to explore the associations between ambient air pollution and childhood hospitalisations for respiratory diseases. Stratification analyses were performed by gender and age group to identify the vulnerable populations. A 10 μg/m³ increased PM_2.5 and SO₂ was associated with hospital admissions for respiratory diseases among children with the greatest relative risk of RR 1.089 (95% CI 1.001-1.183) at cumulative lag 0-2 days and RR 1.229 (95% CI 1.073-1.409) at cumulative lag 0-6 days, respectively. There was no significant association between short-term exposure of PM₁₀, NO₂, CO, and O₃ with childhood respiratory hospitalisation. The association between PM_2.5 and SO₂ exposure and hospital admissions for childhood respiratory diseases in the two pollutants model remained statistically significant. There were stronger associations in younger children aged 0-4 years and girls. This study reveals that short-term exposure to SO₂ was associated with a higher risk of respiratory hospitalisations among children in Bintulu than PM_2.5. Better air quality control is necessary for children's health living in the natural gas industrial area.

Probiotics, prebiotics, and synbiotics to prevent or combat air pollution consequences: The gut-lung axis

Air pollution exposure is a public health emergency, which attributes globally to an estimated seven million deaths on a yearly basis We are all exposed to air pollutants, varying from ambient air pollution hanging over cities to dust inside the home. It is a mixture of airborne particulate matter and gases that can be subdivided into three categories based on particle diameter. The smallest category called PM_0.1 is the most abundant. A fraction of the particles included in this category might enter the blood stream spreading to other parts of the body. As air pollutants can enter the body via the lungs and gut, growing evidence links its exposure to gastrointestinal and respiratory impairments and diseases, like asthma, rhinitis, respiratory tract infections, Crohn's disease, ulcerative colitis, and abdominal pain. It has become evident that there exists a crosstalk between the respiratory and gastrointestinal tracts, commonly referred to as the gut-lung axis. Via microbial secretions, metabolites, immune mediators and lipid profiles, these two separate organ systems can influence each other. Well-known immunomodulators and gut health stimulators are probiotics, prebiotics, together called synbiotics. They might combat air pollution-induced systemic inflammation and oxidative stress by optimizing the microbiota composition and microbial metabolites, thereby stimulating anti-inflammatory pathways and strengthening mucosal and epithelial barriers. Although clinical studies investigating the role of probiotics, prebiotics, and synbiotics in an air pollution setting are lacking, these interventions show promising health promoting effects by affecting the gastrointestinal- and respiratory tract. This review summarizes the current data on how air pollution can affect the gut-lung axis and might impact gut and lung health. It will further elaborate on the potential role of probiotics, prebiotics and synbiotics on the gut-lung axis, and gut and lung health.

Sex Plays a Multifaceted Role in Asthma Pathogenesis

Sex is considered an important risk factor for asthma onset and exacerbation. The prevalence of asthma is higher in boys than in girls during childhood, which shows a reverse trend after puberty—it becomes higher in adult females than in adult males. In addition, asthma severity, characterized by the rate of hospitalization and relapse after discharge from the emergency department, is higher in female patients. Basic research indicates that female sex hormones enhance type 2 adaptive immune responses, and male sex hormones negatively regulate type 2 innate immune responses. However, whether hormone replacement therapy in postmenopausal women increases the risk of current asthma and asthma onset remains controversial in clinical settings. Recently, sex has also been shown to influence the pathophysiology of asthma in its relationship with genetic or other environmental factors, which modulate asthmatic immune responses in the airway mucosa. In this narrative review, we highlight the role of sex in the continuity of the asthmatic immune response from sensing allergens to Th2 cell activation based on our own data. In addition, we elucidate the interactive role of sex with genetic or environmental factors in asthma exacerbation in women.

Ozone Exposure and Asthma Attack in Children

Background

Increasing evidence indicated that ozone (O3) exposure could trigger asthma attacks in children. However, the effect of O3 at low concentrations is uncertain.

Purpose

This study aimed to explore the effects of O3 exposure at low concentrations on asthma attacks in children.

Methods

A total of 3,475 children with asthma attacks from the First Affiliated Hospital of Xiamen University were available for the analyses. Air pollution data and meteorological data in Xiamen during 2016-2019 were also collected. A case-crossover design and conditional logistic regression models were conducted to evaluate the association between asthma attacks and outdoor air pollution with lag structures (from lag 0 to lag 6) in both single and multi-pollutant models. Furthermore, we estimated the influence of various levels of O3 exposure on an asthma attack in three groups categorized by maximum daily 8-h sliding average ozone (O3-8 h) (O3-8 h ≥ 100 μg/m3, O3-8 h: 80-99 μg/m3, O3-8 h < 80 μg/m3).

Results

For both single-pollutant models and multi-pollutant models, when O3-8 h was higher than 80 μg/m3, O3 exposure was increased the risk of acute asthma attacks on each day of lag. The effect of O3 on children with asthma was significant when O3 concentration was higher than 100 μg/m3.

Conclusion

O3 concentration above 80 μg/m3 contributed to an increased risk of asthma attacks in children.

Association between exposure to air pollution and risk of allergic rhinitis: A systematic review and meta-analysis

BACKGROUND

Allergic rhinitis (AR) is one of the most common allergic diseases in the world, and usually persists throughout the activity. Epidemiological studies have shown a positive association between air pollution and allergic rhinitis. However, we could not find any meta-analysis of the risk of air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, O₃ and CO) on the prevalence of AR in people of all ages.

OBJECTIVES

Carry out a meta-analysis on the results of recent studies (up to 2020) to present valid information about exposure to air pollution and risk of prevalence of AR.

METHODS

We systematically searched three databases for studies up to December 17, 2020, including air pollution and AR. Random effect models were conducted to estimate the pooled odds ratios (ORs) and 95% confidence intervals (95% CIs). Subgroup analysis, funnel plot, Egger's test, and the trim-and-fill method were also conducted.

RESULTS

Thirty-five studies across 12 countries, including a total of 453,470 participants, were included. The OR per 10 μg/m³ increase of pollutants was 1.13 (1.04-1.22) for PM₁₀ and 1.12 (1.05-1.20) for PM_2.5. The OR per 10 μg/m³ increment of gaseous pollutants were 1.13 (1.07-1.20) for NO₂, 1.13 (1.04-1.22) for SO₂ and 1.07 (1.01-1.12) for O₃. No significant association was observed between CO and AR. Children or adolescents are more sensitive to air pollution than adults. The effects of PM₁₀ and SO₂ were significantly stronger in Europe than Asia. The effects of air pollutants were more significant and higher in developing countries than in developed countries, except for PM₁₀. A significant difference of subgroup test was found between developed and developing countries of NO₂.

CONCLUSION

This meta-analysis showed a positive association between air pollution and the prevalence of allergic rhinitis, and identified geographic area and economic level as the potential modifiers for the association.

Assessing the impact of air pollutants on clinical visits for childhood allergic respiratory disease induced by house dust mite in Shanghai, China

Background

The prevalence of allergic respiratory disease (ARD) is increasing worldwide during the last few decades, causing a great disease burden especially for children. Air pollution has been increasingly considered as a potential contributor to this trend, but its role in ARD induced by house dust mite (HDM-ARD) remains unclear, especially in time-series study.

Methods

A positive reporting of respiratory allergy to named allergens was included by serum specific IgE testing. A time series Quasi-Poisson regression with distributed lag non-linear model, combined with generalized linear model was used to examine the effects of air pollutants on ARD, HDM-ARD and ARD induced by non-house dust mite (NHDM-ARD).

Results

A total of 16,249 cases of ARD, including 8,719 HDM-ARD and 8,070 NHDM-ARD from 1 Jan 2013 to 31 Dec 2017 were involved in this study. Air pollutants were significantly associated with clinical visits for childhood ARD and HDM-ARD. Exposure to higher O₃ and interquartile range (IQR) increment in O₃ (40.6 µg/m³) increased the risks of clinical visits for childhood HDM-ARD (RR_lag0-5 for the 95th percentile of O₃: 1.26, 95% confidence interval (CI): 1.03, 1.55; RR_lag0-5 for IQR increment (40.6 µg/m³): 1.09, 95% CI: 1.01, 1.17) and ARD (RR_lag0-5 for the 95th percentile of O₃: 1.19, 95% CI: 1.03, 1.38; RR_lag0-5 for IQR increment (40.6 µg/m³): 1.06, 95% CI: 1.01, 1.12). In addition, higher O₃ was associated with increased RR of boys with ARD (RR_lag0-5 for the 95th percentile: 1.26, 95% CI: 1.05, 1.51; RR_lag0-5 for IQR increment (40.6 µg/m³): 1.09, 95% CI: 1.02, 1.16) and HDM-ARD (RR_lag0-5 for the 95th percentile: 1.36, 95% CI: 1.06, 1.75; RR_lag0-5 for IQR increment (40.6 µg/m³): 1.11, 95% CI: 1.02, 1.22), but not in girls.

Conclusions

Exposure to O₃ appeared to be a trigger of clinical visits for childhood ARD, especially for HDM-ARD and boys. These findings provide novel evidence on the impact of air pollution on HDM-ARD, which may have significant implications for designing effective intervention programs to control and prevent childhood ARD, especially HDM-ARD, in China and other similar developing countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01967-1.

Early life exposure to air pollution and cell-mediated immune responses in preschoolers

BACKGROUND

Exposure to air pollution has been linked with altered immune function in adults, but little is known about its effects on early life. This study aimed to investigate the effects of exposure to air pollution during prenatal and postnatal windows on cell-mediated immune function in preschoolers.

METHODS

Pre-school aged children (2.9 ± 0.5 y old, n = 391) were recruited from a mother-child cohort study in Wuhan, China. We used a spatial-temporal land use regression (LUR) model to estimate exposures of particulate matter with aerodynamic diameters ≤2.5 μm (PM_2.5) and ≤10 μm (PM₁₀), and nitrogen dioxide (NO₂) during the specific trimesters of pregnancy and the first two postnatal years. We measured peripheral blood T lymphocyte subsets and plasma cytokines as indicators of cellular immune function. We used multiple informant models to examine the associations of prenatal and postnatal exposures to air pollution with cell-mediated immune function.

RESULTS

Prenatal exposures to PM_2.5, PM₁₀, and NO₂ during early pregnancy were negatively associated with %CD3⁺ and %CD3⁺CD8⁺ cells, and during late pregnancy were positively associated with %CD3⁺ cells. Postnatal exposures to these air pollutants during 1-y or 2-y childhood were positively associated with IL-4, IL-5, IL-6, and TNF-α. We also observed that the associations of prenatal or postnatal air pollution exposures with cellular immune responses varied by child's sex.

CONCLUSIONS

Our results suggest that exposure to air pollution during different critical windows of early life may differentially alter cellular immune responses, and these effects appear to be sex-specific.

Will Smog Cause Mental Health Problems? Indication from a Microsurvey of 35 Major Cities in China

Using the survey data of 21,861 participants from 35 major cities in China in 2018 and 2019, the effect of air quality on participants’ mental health was empirically tested based on the ordered probit model. The results showed that smog can significantly influence the mental health of participants. The better the air quality, the better the participants’ mental health, while poor air quality results in poor mental health. The older and higher-paid participants demonstrated poorer mental health. Additionally, for different health conditions, the air quality had different effects on the participants’ mental health. The healthier the participants, the more sensitive their mental health to changes in air pollution; the poorer the physical condition of the participants, the less sensitive their mental health to changes in air quality. Therefore, we need to more comprehensively and scientifically understand the effect of air quality on health. We need to pay attention not only to the adverse effects of smog on participants’ physical health, but also to its effects on participants’ mental health to improve both the physical and mental health of participants by improving the air quality.

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.

Associations of fine particulate matter and its constituents with airway inflammation, lung function, and buccal mucosa microbiota in children

BACKGROUND

Previous studies have suggested acute effects of ambient fine particulate matter (PM_2.5) air pollution on respiratory health among children, but evidence for PM_2.5 constituents and respiratory health were still limited.

OBJECTIVES

To investigate associations of short-term exposure to PM_2.5 and its constituents with airway inflammation, lung function, and airway microbiota in children.

METHODS

We conducted a longitudinal panel study with 3 repeated health measurements among 62 children in Shanghai, China from November 2018 to June 2019. Respiratory health was measured by fractional exhaled nitric oxide (FeNO), saliva tumor necrosis factor-α (TNF-α), lung function (forced vital capacity and forced exhaled volume in 1 s), and microbiota diversity in buccal mucosa samples. Based on the linear mixed-effect models, we applied the single-constituent models and the constituent-PM_2.5 adjustment models to examine the associations between PM_2.5 constituents and health outcomes.

RESULT

Short-term exposure to PM_2.5 was associated with higher TNF-α, FeNO levels and reduced lung function. Among all constituents, organic carbon, elemental carbon, NO₃^- and NH₄⁺ had the consistent and strongest associations with airway inflammation biomarkers and lung function parameters, followed by metallic elements. We also found short-term PM_2.5 exposure was associated with decreased diversity in buccal mucosa bacterial community and two bacterial phyla, Fusobacteria and Proteobacteria, were identified as differential microbes with PM_2.5 exposure.

CONCLUSION

Short-term exposure to PM_2.5 may impair children's respiratory health represented by higher airway inflammation, lower lung function and altered buccal mucosa microbial colonization. Organic carbon, elemental carbon, NO₃^- and NH₄⁺ may dominate these effects.

Frequency of asthma exacerbation in children during the coronavirus disease pandemic with strict mitigative countermeasures

BACKGROUND

Strict countermeasures for coronavirus disease (COVID-19) were undertaken in China without knowing their influence on asthma.

OBJECTIVE

To investigate the associations between the frequencies of asthma exacerbations and respiratory infections and air pollutants before and during the COVID-19 pandemic, which were direct consequences of countermeasures undertaken for the pandemic.

METHODS

Asthma exacerbations and respiratory infections among hospitalized children in the permanent population of Guangzhou City, China, from February to June 2016-2019 (before the pandemic) to February to June 2020 (during the pandemic) were collected in this cross-sectional study in Guangzhou.

RESULTS

The number of asthma exacerbation cases per month documented in the Guangzhou Women and Children's Hospital before (median: 13.5; range: 0-48) and during (median: 20; range: 0-34) the mitigative response to the COVID-19 pandemic was similar. The frequency of severe asthma exacerbation cases per month decreased, whereas that of mild asthma exacerbation cases per year increased (p = .004). The number of patients hospitalized with infectious respiratory diseases decreased from 146 (range: 90-172) per month before the pandemic to 42 (range: 33-57) per month during the pandemic (p = .004). Most pathogens and air pollutants decreased during the COVID-19 pandemic. The frequency of severe asthma exacerbations positively correlated to that of respiratory infections in children, but did not correlate to air pollutants.

CONCLUSION

Strict countermeasures undertaken for the pandemic were associated with a decreased the frequency of infectious respiratory diseases and severe asthma exacerbations among urban children.

Effect of particulate matter exposure on the prevalence of allergic rhinitis in children: A systematic review and meta-analysis

Among various air pollutants, particulate matter (PM) is the most harmful and representative pollutant. At the same time, allergic rhinitis (AR) is getting more and more attention, so we explore the relationship between PM and the prevalence of AR among children. Then, PubMed, Web of Science, Google Scholar was used to search for relevant studies up to January 2020. Literature quality assessment was processed using the Newcastle-Ottawa Scale (NOS) evaluation scale. Adjusted odds ratio (OR) with corresponding 95% confidence interval (CI) was retrieved from individual studies and pooled to generate a summary effect via STATA software. Besides, we test the result stability by Egger's test and funnel plot, and using the trim-and-fill method to modify the possible asymmetric funnel graph. 21 studies were included in the meta-analysis. 9 articles reported about PM2.5 on childhood AR (1.09, 95%CI: 1.01, 1.17, per 10 μg/m3 increase). 15 articles reported about PM10 on childhood AR (1.06, 95%CI: 1.02,1.11, per 10 μg/m3 increase), PM2.5 exposure has a bigger effect on children AR than PM10. In addition, a series of subgroup analysis was performed, and we found that PM2.5 and PM10 have different performances in different subgroups. In addition to this, we analyzed the sources of heterogeneity of the study. Apart from the results we got all have good stability without publication bias. Therefore, it can be concluded that exposure to PM may increase the prevalence of AR among children.

SARS-CoV-2 infection, COVID-19 pathogenesis, and exposure to air pollution: What is the connection?

Exposure to air pollutants has been previously associated with respiratory viral infections, including influenza, measles, mumps, rhinovirus, and respiratory syncytial virus. Epidemiological studies have also suggested that air pollution exposure is associated with increased cases of SARS-CoV-2 infection and COVID-19-associated mortality, although the molecular mechanisms by which pollutant exposure affects viral infection and pathogenesis of COVID-19 remain unknown. In this review, we suggest potential molecular mechanisms that could account for this association. We have focused on the potential effect of exposure to nitrogen dioxide (NO2 ), ozone (O3 ), and particulate matter (PM) since there are studies investigating how exposure to these pollutants affects the life cycle of other viruses. We have concluded that pollutant exposure may affect different stages of the viral life cycle, including inhibition of mucociliary clearance, alteration of viral receptors and proteases required for entry, changes to antiviral interferon production and viral replication, changes in viral assembly mediated by autophagy, prevention of uptake by macrophages, and promotion of viral spread by increasing epithelial permeability. We believe that exposure to pollutants skews adaptive immune responses toward bacterial/allergic immune responses, as opposed to antiviral responses. Exposure to air pollutants could also predispose exposed populations toward developing COIVD-19-associated immunopathology, enhancing virus-induced tissue inflammation and damage.

External Environmental Pollution as a Risk Factor for Asthma

Air pollution is a worrisome risk factor for global morbidity and mortality and plays a special role in many respiratory conditions. It contributes to around 8 million deaths/year, with outdoor exposure being responsible for more than 4.2 million deaths throughout the world, while more than 3.8 million die from situations related to indoor pollution. Pollutant agents induce several respiratory symptoms. In addition, there is a clear interference in numerous asthma outcomes, such as incidence, prevalence, hospital admission, visits to emergency departments, mortality, and asthma attacks, among others. The particulate matter group of pollutants includes coarse particles/PM₁₀, fine particles/PM_2.5, and ultrafine particles/PM_0.1. The gaseous components include ground-level ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide. The timing, load, and route of allergen exposure are other items affecting allergic disease phenotypes. The complex interaction between pollutant exposures and human host factors has an implication in the development and rise of asthma as a public health problem. However, there are hiatuses in the understanding of the pathways in this disease. The routes through which pollutants induce asthma are multiple, and include the epigenetic changes that occur in the respiratory tract microbiome, oxidative stress, and immune dysregulation. In addition, the expansion of the modern Westernized lifestyle, which is characterized by intense urbanization and more time spent indoors, resulted in greater exposure to polluted air. Another point to consider is the different role of the environment according to age groups. Children growing up in economically disadvantaged neighborhoods suffer more important negative health impacts. This narrative review highlights the principal polluting agents, their sources of emission, epidemiological findings, and mechanistic evidence that links environmental exposures to asthma.

Association between ambient air pollution and hyperuricemia in traffic police officers in China: a cohort study

To evaluate the association between ambient air pollution and hyperuricemia, we prospectively followed 1748 traffic police officers without hyperuricemia at baseline (2009-2014) from 11 districts in Guangzhou, China. We calculated six-year average PM₁₀, SO₂ and NO₂ concentrations using data collected from air monitoring stations. The hazard ratios for hyperuricemia per 10 µg/m³ increase in air pollutants were 1.46 (95% CI: 1.28-1.68) for PM₁₀, 1.23 (95% CI: 1.00-1.51) for SO₂, and 1.43 (95% CI: 1.26-1.61) for NO₂. We also identified changes in the ratio of serum uric acid to serum creatinine concentrations (ua/cre) per 10 µg/m³ increase in air pollutants as 11.54% (95% CI: 8.14%-14.93%) higher for PM₁₀, 5.09% (95% CI: 2.76%-7.42%) higher for SO₂, and 5.13% (95% CI: 2.35%-7.92%) higher for NO₂, respectively. Long-term exposure to ambient air pollution was associated with a higher incidence of hyperuricemia and an increase in ua/cre among traffic police officers.

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.

Asthma prevalence and control among schoolchildren residing near outdoor air pollution sites

INTRODUCTION

Outdoor air pollution (OAP) contributes to poor asthma outcomes and remains a public health concern in Pittsburgh. The purpose of this study was to determine the prevalence of childhood asthma and its rate of control among Pittsburgh schoolchildren residing near OAP sites.

METHODS

Participants were recruited from schools near OAP sites. Asthma prevalence and control were assessed using a validated survey. Demographics and socioeconomic status were collected by survey, BMI was calculated, secondhand smoke (SHS) exposure was assessed by salivary cotinine levels, and OAP was assessed by mobile platform monitoring. Multivariate analysis adjusted for confounders.

RESULTS

In 1202 Pittsburgh elementary school students surveyed, 50.9% were female, average age was 8.5 years (SD = 1.9), 52.2% were African American and 60.6% had public health insurance. SHS exposure was relatively high at 33.9%, 17.1% of students were obese, and 70% had exposure to particulate matter (PM_2.5) greater than the World Health Organization standard of 10 μg/m³. Overall prevalence of asthma was 22.5% with PM_2.5, nitric oxide (NO_x), sulfur (S), and zinc (Zn) significantly related to odds of asthma. Among the 270 children previously diagnosed with asthma, 59.3% were not well controlled with PM_2.5, black carbon, and silicon (Si) significantly related to odds of uncontrolled asthma.

CONCLUSIONS

These results demonstrate that asthma prevalence and poor disease control are significantly elevated in Pittsburgh schoolchildren exposed to high levels of OAP. Future efforts need to focus on primary prevention of asthma by reducing exposure to OAP in at risk populations.

Construction of a nomogram for predicting the risk of allergic rhinitis among employees of long-distance bus stations in China

This study examined indoor air pollutants and their health effects on allergic rhinitis in 3194 employees of 226 bus station halls and then constructed a nomogram model to predict allergic rhinitis risk in those employees. Indoor air temperature, relative humidity, PM₁₀ , PM_2.5 , total bacteria, and total fungi were measured, and questionnaires were used to collect basic station information and employee health information. The results revealed that the over-standard rates of PM₁₀ , PM_2.5 , total bacteria, and total fungi were 18.16%, 31.13%, 2.22%, and 55.89%, respectively. Seasonal variations were found in temperature, relative humidity, and PM_2.5 . Passenger flow could affect temperature, and total bacteria. Central air conditioning could affect total bacteria. A total of 15.90% of the employees were diagnosed as allergic rhinitis by physicians. Relative humidity, fungi, self-reported allergic rhinitis symptoms, and exposure to smoking were the influencing factors for allergic rhinitis. These four variables were incorporated to construct a nomogram. The concordance index of the nomogram was 0.775 (95% CI: 0.745-0.806) and 0.749 (95% CI: 0.715-0.783) for the training cohort and test cohort, respectively. The calibration plot revealed that the nomogram model exhibited good discrimination and consistency. This nomogram model may help predict the occurrence of allergic rhinitis.

Acute associations between PM2.5 and ozone concentrations and asthma exacerbations among patients with and without allergic comorbidities

Acute effects of outdoor air pollution on asthma exacerbations may vary by asthma phenotype (allergic vs nonallergic). Associations of ambient PM_2.5 and ozone concentrations with acute asthma visits (office, urgent, emergency, and hospitalization) were investigated using electronic medical records. International Classification of Disease codes were used to identify asthmatics, and classify them based on the presence or absence of an allergic comorbidity in their medical records. Daily 24-h average PM_2.5, 8-h maximum ozone, and mean temperature were obtained from a centralized monitor. Using a time-stratified case-crossover approach, pollutant concentrations were modeled using moving averages and distributed lag nonlinear models (lag 0-6) to examine lag associations and nonlinear concentration-response. The adjusted odds ratios for a 10 µg/m³ increase in 3-day moving average (lag 0-2) PM_2.5 in the two-pollutant models among patients with and without allergic comorbidities were 1.10 (95% confidence interval [CI]: 1.07, 1.13) and 1.05 (95% CI: 1.02, 1.09), respectively; and for a 20 ppb increase in 3-day moving average (lag 0-2) ozone were 1.08 (95% CI: 1.02, 1.14) and 1.00 (95% CI: 0.95, 1.05), respectively. Estimated odds ratios among patients with allergic comorbidities were consistently higher across age, sex, and temperature categories. Asthmatics with an allergic comorbidity may be more susceptible to ambient PM_2.5 and ozone.

Early-life exposure to air pollution and childhood allergic diseases: an update on the link and its implications

INTRODUCTION

Although mounting evidence has linked environmental factors with childhood allergies, some specific key issues still remain unclear: what is the main environmental factor? what is the critical timing window? And whether these contribute to the development of disease?

AREAS COVERED

This selective review summarizes recent epidemiological studies on the association between early-life exposure to indoor/outdoor air pollution and childhood allergic diseases. A literature search was conducted in the PubMed and Web of Science for peer-reviewed articles published until April 2020. Exposure to the traffic-related air pollutant, NO₂, exposure during pregnancy and early postnatal periods is found to be associated with childhood allergies, and exposure during different trimesters causes different allergic diseases. However, exposure to classical air pollutants (PM₁₀ and SO₂) also contributes to childhood allergy in developing countries. In addition, early-life exposure to indoor renovation and mold/dampness significantly increases the risk of allergy in children. A synergistic effect between indoor and outdoor air pollution is found in the development of allergic diseases.

EXPERT OPINION

Early-life exposure to outdoor air pollution and indoor environmental factors plays an important role in the development of childhood allergic diseases, and the synergy between indoor and outdoor exposures increases allergy risk. The available findings support the hypothesis of the 'fetal origins of childhood allergy,' with new implications for the effective control and early prevention of childhood allergies.

Benefits of influenza vaccination on the associations between ambient air pollution and allergic respiratory diseases in children and adolescents: New insights from the Seven Northeastern Cities study in China

BACKGROUND

Little information exists on interaction effects between air pollution and influenza vaccination on allergic respiratory diseases. We conducted a large population-based study to evaluate the interaction effects between influenza vaccination and long-term exposure to ambient air pollution on allergic respiratory diseases in children and adolescents.

METHODS

A cross-sectional study was investigated during 2012-2013 in 94 schools from Seven Northeastern Cities (SNEC) in China. Questionnaires surveys were obtained from 56 137 children and adolescents aged 2-17 years. Influenza vaccination was defined as receipt of the influenza vaccine. We estimated air pollutants exposure [nitrogen dioxide (NO₂) and particulate matter with aerodynamic diameters ≤1 μm (PM₁), ≤2.5 μm (PM_2.5) and ≤10 μm (PM₁₀)] using machine learning methods. We employed two-level generalized linear mix effects model to examine interactive effects between influenza vaccination and air pollution exposure on allergic respiratory diseases (asthma, asthma-related symptoms and allergic rhinitis), after controlling for important covariates.

RESULTS

We found statistically significant interactions between influenza vaccination and air pollutants on allergic respiratory diseases and related symptoms (doctor-diagnosed asthma, current wheeze, wheeze, persistent phlegm and allergic rhinitis). The adjusted ORs for doctor-diagnosed asthma, current wheeze and allergic rhinitis among the unvaccinated group per interquartile range (IQR) increase in PM₁ and PM_2.5 were significantly higher than the corresponding ORs among the vaccinated group [For PM₁, doctor-diagnosed asthma: OR: 1.89 (95%CI: 1.57-2.27) vs 1.65 (95%CI: 1.36-2.00); current wheeze: OR: 1.50 (95%CI: 1.22-1.85) vs 1.10 (95%CI: 0.89-1.37); allergic rhinitis: OR: 1.38 (95%CI: 1.15-1.66) vs 1.21 (95%CI: 1.00-1.46). For PM_2.5, doctor-diagnosed asthma: OR: 1.81 (95%CI: 1.52-2.14) vs 1.57 (95%CI: 1.32-1.88); current wheeze: OR: 1.46 (95%CI: 1.21-1.76) vs 1.11 (95%CI: 0.91-1.35); allergic rhinitis: OR: 1.35 (95%CI: 1.14-1.60) vs 1.19 (95%CI: 1.00-1.42)]. The similar patterns were observed for wheeze and persistent phlegm. The corresponding p values for interactions were less than 0.05, respectively. We assessed the risks of PM₁-related and PM_2.5-related current wheeze were decreased by 26.67% (95%CI: 1.04%-45.66%) and 23.97% (95%CI: 0.21%-42.08%) respectively, which was attributable to influenza vaccination (both p for efficiency <0.05).

CONCLUSIONS

Influenza vaccination may play an important role in mitigating the detrimental effects of long-term exposure to ambient air pollution on childhood allergic respiratory diseases. Policy targeted at increasing influenza vaccination may yield co-benefits in terms of reduced allergic respiratory diseases.

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.

Novel Insights on Sex-Related Differences in Asthma

PURPOSE OF REVIEW

Asthma, a common respiratory disease that affects about 10% of the US population, represents a significant public health issue. In the last decade, cumulative evidence has demonstrated sex disparities in asthma, including significant differences in epidemiology, clinical presentation, response to therapies, and health outcomes. Understanding sex-related differences in asthma enables clinicians to provide personalized asthma care and improve asthma outcome.

RECENT FINDINGS

Recent studies on sex-related differences in asthma inform us on mechanism underlying asthma pathogenesis across all age groups. Sex hormones directly modulate immune pathways crucial in asthma pathogenesis and affect individual's response to environmental triggers and medications, such as leukokotriene inhibitors. Not surprisingly, the use of external sex hormone supplementations appears to modulate asthma risk. Identification of sex-specific asthma risk loci through genome-wide association studies also provides supporting evidence on sex-related differences in asthma. There is an interaction between sex and obesity, an interaction that could place females at higher risk for systemic inflammation and, consequently, asthma. In this article, we review epidemiological and clinical studies on sex-related differences in asthma, with a special focus on the role of sex hormones, including hormonal therapies and the asthma-obesity interaction.

Air pollution, respiratory illness and behavioral adaptation: Evidence from South Korea

Air pollution is closely associated with the development of respiratory illness. Behavioral adaptations of people to air pollution may influence its impact, yet this has not been investigated in the literature. Our hypothesis is that people experience and learn the underlying air quality to decide their adaptation, and they have a stronger incentive to behaviorally adapt to the air quality as it deteriorates. We tested our hypothesis on a sample of approximately 25,700 individuals from South Korea from 2002 to 2013 that contained information on daily doctor's visits due to respiratory disease. We matched individuals to the mean of the past seven-day concentration of the particulate matter of size between 2.5 and 10 micrometers (PM10) in their county of residence. We examined whether people living in counties with greater air pollution suffer less from respiratory disease when the concentration increases. For the analysis, we separated counties into quintiles based on their mean seven-day PM10, and regressed the binary indicator of a daily doctor's visit with a resulting diagnosis of respiratory disease on the seven-day PM10 concentration of the county of residence interacted with the quintile dummies. The key findings are that a 1-standard-deviation increase in the seven-day PM10 concentration in the two lowest quintiles is associated with an increase of 0.054 percentage points in the likelihood of a doctor's visit with a resulting diagnosis of respiratory disease, which is about 40% larger than the effect in higher quintiles, and the size of 1-standard-deviation gradually increases from 0.037 percentage points in the third quintile to 0.040 percentage points in the fifth quintile. The smaller increase in the likelihood of respiratory disease in more polluted locations can be explained by the behavioral adaptation to the environment, but the effectiveness of the adaptation seems limited among the highly polluted locations.

Metabolic Outcomes in Southern Italian Preadolescents Residing Near an Industrial Complex: The Role of Residential Location and Socioeconomic Status

Evidence suggests that environmental exposures and socioeconomic factors may interact to produce metabolic changes in children. We assessed the influence of residential location and socioeconomic status (SES) on pediatric body mass index (BMI) Z-score and fasting blood glucose (FBG) concentration. Participants included 214 children aged 6-11 years who live near a large industrial complex in Taranto, Italy. Participants were grouped into residential zones based on the distance between their home address and the complex periphery (Zone 1: 0.000-4.999 km, Zone 2: 5.000-9.999 km, Zone 3: 10.000-15.000 km). BMI Z-scores were calculated via World Health Organization (WHO) pediatric reference curves. FBG was obtained via venous blood sampling. Closer residential location to the industrial complex on the order of 5.000 km was significantly associated with worsened metabolic outcomes, particularly in female children. Zone 1 participants had higher BMI-adjusted FBG than Zone 2 and 3 participants (p < 0.05 versus Zone 2; p < 0.01 versus Zone 3). SES did not significantly influence BMI-adjusted FBG. Moreover, BMI Z-scores indicated high rates of overweight (22.0%) and obesity (22.9%) in the cohort. BMI Z-score was not significantly associated with SES or residential zone but was negatively associated with maternal education level (p < 0.05). These results offer new evidence that residing near industrial activity may predict adverse effects on child metabolic health.

Chemical fractionation of heavy metals in fine particulate matter and their health risk assessment through inhalation exposure pathway

Samples of PM_2.5 were collected from an urban area close to a national highway in Agra, India and sequentially extracted into four different fractions: water soluble (F1), reducible (F2), oxidizable (F3) and residual fraction (F4) for chemical fractionation of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni) and lead (Pb). The metals were analyzed by inductively coupled plasma optical emission spectroscopy in each fraction. The average mass concentration of PM_2.5 was 93 ± 24 μg m^-3.The total concentrations of Cr, Pb, Ni, Co, As and Cd in fine particle were 192 ± 54, 128 ± 25, 108 ± 34, 36 ± 6, 35 ± 5 and 8 ± 2 ng m^-3, respectively. Results indicated that Cd and Co had the most bioavailability indexes. Risk Assessment Code and contamination factors were calculated to assess the environmental risk. The present study evaluated the potential Pb hazard to young children using the Integrated Exposure Uptake Biokinetic Model. From the model, the probability density of PbB (blood lead level) revealed that at the prevailing atmospheric concentration, 0.302 children are expected to have PbB concentrations exceeding 10 μg dL^-1 and an estimated IQ (intelligence quotient) loss of 1.8 points. The predicted blood Pb levels belong to Group 3 (PbB < 5 μg dL^-1). Based on the bioavailable fractions, carcinogenic and non-carcinogenic risks via inhalation exposure were assessed for infants, toddlers, children, males and females. The hazard index for potential toxic metals was 2.50, which was higher than the safe limit (1). However, the combined carcinogenic risk for infants, toddlers, children, males and females was marginally higher than the precautionary criterion (10^-6).

Prenatal particulate matter affects new asthma via airway hyperresponsiveness in schoolchildren

BACKGROUND

The most relevant time of PM₁₀ exposure to affect airway hyperresponsiveness (AHR) and new development of asthma in school-aged children is unclear. The aims of this study were to investigate the most critical time of PM₁₀ exposure to affect AHR and new diagnosis of asthma from AHR in school-aged children.

METHODS

Elementary schoolchildren (n = 3570) have been enrolled in a nationwide prospective 4-year follow-up survey in Korea from 2005 to 2006. Individual annual PM₁₀ exposure was estimated by using an ordinary kriging method from the prenatal period to 7 years of age. AHR at 7 years was defined by a methacholine PC₂₀ ≤8 mg/mL.

RESULTS

PM₁₀ exposure during pregnancy and at 1 year of age showed significant effects on AHR (aOR: 1.694, 95% CI: 1.298-2.209; and aOR: 1.750, 95% CI: 1.343-2.282, respectively). PM₁₀ exposure during pregnancy was associated with the risk of a new diagnosis of asthma (aOR: 2.056, 95% CI: 1.240-3.409), with the highest risk in children with AHR at age 7 (aOR: 6.080, 95% CI: 2.150-17.195). PM₁₀ exposure in the second trimester was associated with the highest risk of a new diagnosis of asthma in children with AHR at age 7 (aOR: 4.136, 95% CI: 1.657-10.326).

CONCLUSIONS

Prenatal PM₁₀ exposure in the second trimester is associated with an increased risk of a new diagnosis of asthma in school-aged children with AHR at 7 years. This study suggests that PM₁₀ exposure during a specific trimester in utero may affect the onset of childhood asthma via AHR.

Onset of respiratory symptoms among Chinese students: associations with dampness and redecoration, PM10, NO2, SO2 and inadequate ventilation in the school

Objective: To study onset of respiratory symptoms among students in China in relation to the school and the home environment. Methods: A two-year prospective cohort study among 1325 students in eight schools. Air pollution was measured at baseline in the schools. Respiratory symptoms and the home environment were assessed by a questionnaire. Results: The 2-year onset was 14.3%, 23.2%, 15.4%, 4.7% and 37.3% for wheeze, daytime attacks of breathlessness, nocturnal cough, nocturnal wheeze/breathlessness and respiratory infections, respectively. The mean concentrations of PM₁₀, SO₂, NO_2, ozone and CO₂ in the classrooms were 129 µg/m³, 68.0 µg/m³, 43.2 µg/m³, 8.6 µg/m³ and 1208 ppm, respectively. Environmental tobacco smoke (ETS), dampness/mold at home and ozone in the classroom were associated with onset of wheeze. Onset of daytime breathlessness was associated with redecoration and dampness/mold at home and CO₂ and relative air humidity (RH) in the classrooms. Dampness/mold at home, PM₁₀, CO₂ and RH in the classrooms and outdoor PM₁₀, SO₂ and NO₂ were associated with onset of nocturnal cough. Onset of nocturnal wheeze/breathlessness was associated with dampness/mold at home and RH and PM₁₀ in the classrooms. Respiratory infections were more common at higher levels of outdoor PM₁₀. Conclusions: Air pollution (PM₁₀, ozone, SO₂ and NO₂) and inadequate ventilation flow in the classrooms (indicated by CO₂ > 1000 ppm) and ETS, dampness or mold and chemical emissions from redecoration at home can increase onset of respiratory symptoms.

The impact of outdoor air pollutants on outpatient visits for respiratory diseases during 2012-2016 in Jinan, China

Background

Few studies have investigated the associations between outdoor air pollution and outpatient visits for respiratory diseases (RDs) in general population.

Methods

We collected daily outpatient data of primary RDs from five hospitals in Jinan during January 2012 and December 2016, as well as daily measurements of air pollutants from the Jinan Environmental Monitoring Center and daily meteorological variables from the China Meteorological Data Sharing Service System. A generalized additive model (GAM) with quasi-Poisson regression was constructed to estimate the associations between daily average concentrations of outdoor air pollutants (PM_2.5,PM₁₀, SO₂, NO₂, CO and O₃) and daily outpatient visits of RDs after adjusting for long-time trends, seasonality, the “day of the week” effect, and weather conditions. Subgroup analysis stratified by gender, age group and the type of RDs was conducted.

Results

A total of 1,373,658 outpatient visits for RDs were identified. Increases of 10 μg/m³ in PM_2.5, PM₁₀, NO₂, CO and O₃ were associated with0.168% (95% CI, 0.072–0.265%), 0.149% (95% CI, 0.082–0.215%), 0.527% (95% CI, 0.211–0.843%), 0.013% (95% CI, 0.003–0.023%), and 0.189% (95% CI, 0.032–0.347%) increases in daily outpatient visits for RDs, respectively. PM_2.5 and PM₁₀ showed instant and continuous effects, while NO₂, CO and O₃ showed delayed effects on outpatient visits for RDs. In stratification analysis, PM_2.5 and PM₁₀ were associated with acute RDs only.

Conclusions

Exposure to outdoor air pollutants including PM_2.5, PM₁₀, NO₂, CO and O₃ associated with increased risk of outpatient visits for RDs.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0958-x) contains supplementary material, which is available to authorized users.

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.

Particulate matter containing environmentally persistent free radicals induces AhR-dependent cytokine and reactive oxygen species production in human bronchial epithelial cells

Particulate matter (PM) is emitted during the combustion of fuels and wastes. PM exposure exacerbates pulmonary diseases, and the mechanism may involve oxidative stress. At lower combustion temperatures such as occurs in the cool zone of a flame, aromatic compounds chemisorb to the surface of metal-oxide-containing PM, resulting in the formation of surface-stabilized environmentally persistent free radicals (EPFR). Prior studies showed that PM-containing EPFR redox cycle to produce reactive oxygen species (ROS), and after inhalation, EPFR induce pulmonary inflammation and oxidative stress. Our objective was to elucidate mechanisms linking EPFR-induced oxidant injury with increased cytokine production by pulmonary epithelial cells. We thus treated human bronchial epithelial cells with EPFR at sub-toxic doses and measured ROS and cytokine production. To assess aryl hydrocarbon receptor (AhR) activity, cells were transfected with a luciferase reporter for xenobiotic response element activation. To test whether cytokine production was dependent upon AhR activation or oxidative stress, some cells were co-treated with an antioxidant or an AhR antagonist. EPFR increased IL-6 release in an ROS and AhR- and oxidant-dependent manner. Moreover, EPFR induced an AhR activation that was dependent upon oxidant production, since antioxidant co-treatment blocked AhR activation. On the other hand, EPFR treatment increased a cellular ROS production that was at least partially attenuated by AhR knockdown using siRNA. While AhR activation was correlated with an increased expression of oxidant-producing enzymes like cytochrome P450 CYP1A1, it is possible that AhR activation is both a cause and effect of EPFR-induced ROS. Finally, lipid oxidation products also induced AhR activation. ROS-dependent AhR activation may be a mechanism for altered epithelial cell responses after EPFR exposure, potentially via formation of bioactive lipid or protein oxidation products.

The combined effect of ambient ozone exposure and toxic air releases on hospitalization for asthma among children in Harris County, Texas

This study represents an analysis of the effect of exposure to ambient ozone and toxic air releases on hospitalization for asthma among children in Harris County, Texas. Our study identified temporal and spatial variations in asthma hospitalization across the study region and explored the combined effect of exposure to ambient ozone and air toxics on asthma hospitalization. Asthma hospitalization hot spots and clusters were mostly not located on zip codes with reported high quantities of total air releases of chemical pollutants. There was no significant interaction between ambient ozone exposure and toxic air releases relative to asthma hospitalization. The major predictor of asthma hospitalization was season, with hospitalization rate per 10,000 people for asthma being highest in winter period when ozone levels are usually lowest.

Maternal exposure to particulate matter alters early post-natal lung function and immune cell development

BACKGROUND

In utero exposure to particulate matter (PM) from a range of sources is associated with adverse post-natal health; however, the effect of maternal exposure to community-sampled PM on early post-natal lung and immune development is poorly understood.

OBJECTIVES

Using a mouse model, we aimed to determine whether in utero exposure to PM alters early post-natal lung function and immune cell populations. We used PM collected from ceiling voids in suburban houses as a proxy for community PM exposure.

METHODS

Pregnant C57BL/6 mice were intranasally exposed to ceiling derived PM, or saline alone, at gestational day (E) 13.5, 15.5, and 17.5. When mice were two weeks old, we assessed lung function by the forced oscillation technique, and enumerated T and B cell populations in the spleen and thymus by flow cytometry.

RESULTS

Maternal exposure to PM impaired somatic growth of male offspring resulting in reduced lung volume and deficits in lung function. There was no effect on thymic T cell populations in dams and their male offspring but PM decreased the CD4 +CD25 + T cell population in the female offspring. In contrast, maternal exposure to PM increased splenic CD3 +CD4 + and CD3 +CD8 + T cells in dams, and there was some evidence to suggest inhibition of splenic T cell maturation in male but not female offspring.

CONCLUSIONS

Our findings suggested that maternal exposure to ceiling void PM has the capacity to impair early somatic growth and alter early life immune development in a sex specific manner.

Residential Ambient Traffic in Relation to Childhood Pneumonia among Urban Children in Shandong, China: A Cross-Sectional Study

Pneumonia is a leading cause of childhood death. Few studies have investigated associations between residential ambient environmental exposures and pneumonia. In January⁻April 2015, we conducted a cross-sectional study in Shandong Province (China) and collected 9597 (response rate: 78.7%) parent-reported questionnaires for 3⁻6-year-old children from 69 urban kindergartens. We then selected 5640 children who had never changed residence since birth and examined associations between residential ambient traffic-related facilities and childhood pneumonia considering residential characteristics. Prevalence of doctor-diagnosed pneumonia during lifetime-ever was 25.9%. In the multivariate logistic regression analyses, residence close to a main traffic road (adjusted odds ratio, 95% confidence interval: 1.23, 1.08⁻1.40) and automobile 4S shop (1.76, 1.16⁻2.67) within 200 m, residence close to a filling station within 100 m (1.71, 1.10⁻2.65; reference: >200 m), as well as having a ground car park in the residential community (1.24, 1.08⁻1.42) were significantly associated with childhood pneumonia. The cumulative numbers of these traffic-related facilities had a positive dose-response relationship with the increased odds of childhood pneumonia. These associations and dose-response relationships were stronger among boys and among children with worse bedroom ventilation status during the night. Associations of residence close to the main traffic road and ground car parks in the residential community with childhood pneumonia were stronger among children living in the 1st⁻3rd floors than those living on higher floors. Similar results were found in the two-level (kindergarten-child) logistic regression analyses. Our findings indicate that living near traffic-related facilities is likely a risk factor for childhood pneumonia among urban children. The child's sex, bedroom floor level, and bedroom ventilation could modify associations of ambient traffic-related facilities with childhood pneumonia.

Pollution and respiratory disease: can diet or supplements help? A review

Pollution is known to cause and exacerbate a number of chronic respiratory diseases. The World Health Organisation has placed air pollution as the world's largest environmental health risk factor. There has been recent publicity about the role for diet and anti-oxidants in mitigating the effects of pollution, and this review assesses the evidence for alterations in diet, including vitamin supplementation in abrogating the effects of pollution on asthma and other chronic respiratory diseases. We found evidence to suggest that carotenoids, vitamin D and vitamin E help protect against pollution damage which can trigger asthma, COPD and lung cancer initiation. Vitamin C, curcumin, choline and omega-3 fatty acids may also play a role. The Mediterranean diet appears to be of benefit in patients with airways disease and there appears to be a beneficial effect in smokers however there is no direct evidence regarding protecting against air pollution. More studies investigating the effects of nutrition on rapidly rising air pollution are urgently required. However it is very difficult to design such studies due to the confounding factors of diet, obesity, co-morbid illness, medication and environmental exposure.

Metal composition of ambient PM2.5 influences the pulmonary function of schoolchildren: A case study of school located nearby of an electric arc furnace factory

The present study combined air sampling with pulmonary function tests (PFTs) to determine both the extent of air pollution proximal to an electric arc furnace (EAF) and its impact on human health. The mass concentrations of particulate matter with aerodynamic diameters less than 2.5 µm (PM_2.5) in exposure areas were not significantly higher than the samples taken at a control area. However, the concentrations of five metal elements, Cd, Cr, Cu, Ni, and Zn in PM_2.5 were significantly higher in the exposure area than that of the control area. PFTs showed that the average forced vital capacity (FVC) of boys was decreased with decreasing distance from the EAF factory. With normalization of pulmonary function by age, height, and weight, we found that the FVC became more negative with a decrease in distance from the EAF. Lastly, regression analysis was performed to analyze the impact of the concentrations of the five metals in PM_2.5 on the performance of pulmonary function. The results showed that the metals can be ranked from the highest to the lowest in terms of impact on the FVC of boys as follows: Cr, Cd, Ni, Cu, and Zn. This finding is consistent with the ranking of metal toxicity reported in the literature for a rat lung epithelial cell line. The results of this study showed that only measuring PM_2.5 mass concentrations may not provide a full explanation of its toxicity and health effects. The chemical composition of the PM_2.5 can be an important factor that determined the health impact of PM_2.5.

Respiratory syncytial virus bronchiolitis, weather conditions and air pollution in an Italian urban area: An observational study

BACKGROUND

In this study we sought to evaluate the association between viral bronchiolitis, weather conditions, and air pollution in an urban area in Italy.

METHODS

We included infants hospitalized for acute bronchiolitis from 2004 to 2014. All infants underwent a nasal washing for virus detection. A regional agency network collected meteorological data (mean temperature, relative humidity and wind velocity) and the following air pollutants: sulfur dioxide, nitrogen oxide, carbon monoxide, ozone, benzene and suspended particulate matter measuring less than 10µm (PM10) and less than 2.5µm (PM2.5) in aerodynamic diameter. We obtained mean weekly concentration data for the day of admission, from the urban background monitoring sites nearest to each child's home address. Overdispersed Poisson regression model was fitted and adjusted for seasonality of the respiratory syncytial virus (RSV) infection, to evaluate the impact of individual characteristics and environmental factors on the probability of a being positive RSV.

RESULTS

Of the 723 nasal washings from the infants enrolled, 266 (68%) contained RSV, 63 (16.1%) rhinovirus, 26 (6.6%) human bocavirus, 20 (5.1%) human metapneumovirus, and 16 (2.2%) other viruses. The number of RSV-positive infants correlated negatively with temperature (p < 0.001), and positively with relative humidity (p < 0.001). Air pollutant concentrations differed significantly during the peak RSV months and the other months. Benzene concentration was independently associated with RSV incidence (p = 0.0124).

CONCLUSIONS

Seasonal weather conditions and concentration of air pollutants seem to influence RSV-related bronchiolitis epidemics in an Italian urban area.

The effect of size-segregated ambient particulate matter on Th1/Th2-like immune responses in mice

Background

Particulate matter (PM) has been associated with increased pulmonary and cardiovascular mortality and morbidity. Additionally, PM is known to exacerbate asthma. However, whether ambient PM exposure contributes to the onset of asthma, especially in non-atopic children and adults, is less conclusive. The current study aimed to evaluate the effects of size-fractioned PM on lung immune responses in healthy BALB/c mice.

Methods and principal findings

We collected PM₁₀, PM_2.5, PM₁ and PM_0.1 samples from October 2012 to August 2013 in the Taipei Basin. These PM samples were representative of urban traffic pollution. The samples were extracted and sonicated in phosphate-buffered saline (PBS). Female BALB/c mice were exposed to the samples via intratracheal instillation at three different doses: 1.75 mg/kg (35 μg/per mouse), 5 mg/kg (100 μg/per mouse), and 12.5 mg/kg (250 μg/per mouse). The mice were exposed on days 0 and 7, and PBS alone was used as a control. Following the exposures, the expression profiles of inflammatory cells and cytokines in bronchoalveolar lavage fluid (BALF) were assessed. Exposure to PM₁₀ resulted in inflammatory responses, including the recruitment of neutrophils and the induction of T helper 1 (Th1) cell-related cytokine release, such as TNF-α and IFN-γ. Furthermore, an allergic immune response, including the recruitment of eosinophils and the up-regulation of T helper 2 (Th2) cell-related cytokine release, such as IL-5 and IL-13, was also observed in the BALF of mice exposed to PM₁₀.

Conclusions

Our study showed that exposure to PM alone caused mixed Th1/Th2 inflammatory responses in healthy mice. These findings support the hypothesis that PM may contribute to the onset of asthma.