Ambient air pollution and infant health: a narrative review

Associations of long-term exposure to PM2.5 and its constituents with children renal function: a national retrospective study in China

INTRODUCTION

Ambient fine particulate matter with aerodynamic diameter ≤2.5 μm (PM2.5) harms adult's renal health. However, research on the associations of PM2.5 and its chemical constituents (black carbon (BC), ammonium ( [Formula: see text] ), nitrate (NO3-), organic matter (OM), and sulfate (SO42-)) with children' kidney health is lacking.

OBJECTIVES

The aim of this research was to estimate the associations between long-term exposures to PM2.5 and its constituents and children' estimated glomerular filtration rate (eGFR).

METHODS

We investigated 9770 children from 5 provinces across China during 2016-2017. The eGFR was calculated from serum creatinine. We estimated the mean concentration of PM2.5 and PM2.5 compositions (BC, [Formula: see text] , NO3-, OM, SO42-) during pregnancy, infancy and preschool period for each subject. A generalized linear mixed-effects model was utilized to estimate associations of PM2.5 and its constituents with eGFR. Stratified analyses were conducted to explore effect modifications of sex and urbanicity.

RESULTS

During the full pregnancy, each interquartile range (IQR) increase in PM2.5 mass (49.07 μg/m3), SO42- (9.14 μg/m3), BC (1.85 μg/m3), [Formula: see text] (7.38 μg/m3), NO3- (12.23 μg/m3) and OM (9.02 μg/m3) was associated with decreased eGFR (ml/min/1.73 m2), with changes of -1.80 (95 % CI: -2.82, -0.78), -1.70 (95 % CI: -2.71, -0.69), -1.83 (95 % CI: -2.63, -1.03), -6.87 (95 % CI: -8.44, -5.30), -7.24 (95 % CI: -9.02, -5.45), and -2.20 (95 % CI: -3.12, -1.28), respectively. In infancy, higher levels of BC, [Formula: see text] , NO3-, and OM were negatively associated with eGFR, and similar associations were found during the preschool period for [Formula: see text] , NO3-, and OM. Furthermore, children living in rural areas were particularly sensitive to PM2.5.

CONCLUSION

Long-term exposures to PM2.5 and some constituents were negatively associated with children's eGFR. Additionally, the associations of [Formula: see text] and NO3- constituents were more pronounced with renal health than the other chemical constituents. Targeted policies are needed to protect kidney health from PM2.5 exposure.

Children-specific environmental protection strategies are needed in China

China, home to over 250 million children, has witnessed remarkable economic development in recent decades, successfully addressing many issues related to basic hygiene and sanitation in children, thereby altering the childhood disease spectrum. However, the emergence of environment-related disorders among children has become a significant concern. Despite the rapid accumulation of scientific knowledge on the adverse effects of environmental pollution on child health, the availability of children-specific protective strategies and actions remains alarmingly low. This commentary synthesizes the information and viewpoints presented and discussed by experts at the International Forum on Children's Environmental Health in China. It summarizes the strategies and actions proposed to reduce adverse environmental exposure and protect children's short- and long-term health and a call for more children-centered evidence-action transformation. The following four specific actions were proposed: (1) strengthen health education in parents, caregivers, and children, and personal protection for children; (2) monitor child exposure and environment-related health status; (3) set up child-specific interventions and regulations; and (4) conduct more research on environment exposures and child health.

Life-course exposure to air pollution and the risk of dementia in the Lothian Birth Cohort 1936

Background

Air pollution in later life has been associated with dementia; however, limited research has investigated the association between air pollution across the life course, either at specific life periods or cumulatively. The project investigates the association of air pollution with dementia via a life-course epidemiological approach.

Methods

Participants of the Lothian Birth Cohort, born in 1936, provided lifetime residential history in 2014. Participant's air pollution exposure for time periods 1935, 1950, 1970, 1980, 1990, 2001, and 2007 was modeled using an atmospheric chemistry transport model. Lifetime cumulative exposures were calculated as time-weighted mean exposure. Of 572 participants, 67 developed all-cause dementia [35 with Alzheimer's dementia (AD)] by wave 5 (~82 years). Cox proportional hazards and competing risk models assessed the association between all-cause dementia and AD with particulate matter (diameter of ≤2.5 µm) PM2.5 and nitrogen dioxide (NO2) exposure at specific life periods and cumulatively. False discovery rate (FDR) correction was applied for multiple testing.

Results

The mean follow-up was 11.26 years. One standard deviation (SD) higher exposure to air pollution in 1935 (PM2.5 = 14.03 μg/m3, NO2 = 5.35 μg/m3) was positively linked but not statistically significant to all-cause dementia [PM2.5 hazard ratio (HR) = 1.16, 95% confidence interval (CI) = 0.90, 1.49; NO2 HR = 1.13, 95% CI = 0.88, 1.47] and AD (PM2.5 HR = 1.38, 95% CI = 1.00, 1.91; NO2 HR = 1.35, 95% CI = 0.92, 1.99). In the competing risk model, one SD elevated PM2.5 exposure (1.12 μg/m3) in 1990 was inversely associated with dementia (subdistribution HR = 0.82, 95% CI = 0.67, 0.99) at P = 0.034 but not after FDR correction (P FDR = 0.442). Higher cumulative PM2.5 per one SD was associated with an increased risk of all-cause dementia and AD for all accumulation models except for the early-life model.

Conclusion

The in-utero and early-life exposure to PM2.5 and NO2 was associated with higher AD and all-cause dementia risk, suggesting a sensitive/critical period. Cumulative exposure to PM2.5 across the life course was associated with higher dementia risk. Midlife PM2.5 exposure's negative association with all-cause dementia risk may stem from unaddressed confounders or bias.

Epidemiology of neonatal disorders attributable to low birthweight-global burden of disease research, 1990-2021

Background

To evaluate global, regional, and national trends in the burden of neonatal diseases attributable to LBW, as well as associated health inequalities, from 1990 to 2021.

Methods

Using data from the Global Burden of Disease Study (GBD2021), we analyzed deaths and DALYs due to LBW-attributable neonatal diseases. Data were stratified by gender, geographic region, epidemiological characteristics, and SDI levels. Trends and influencing factors were investigated through Joinpoint regression, health inequality analysis, and frontier modeling.

Results

In 2021, the global age-standardized mortality rate (ASMR) and age-standardized disability-adjusted life year (DALY) rate (ASDR) for neonatal diseases associated with low birth weight (LBW) were 22.76 [95% uncertainty interval (UI): 19.63-26.40] and 2,227.54 (95% UI: 1,939.96-2,563.52) per 100,000, respectively. Over the past 32 years, these rates have consistently declined, with average annual percentage changes (AAPCs) of -1.40 [95% confidence interval (CI): -1.48 to -1.33] for ASMR and -1.27 (95% CI: -1.34 to -1.21) for ASDR. Notably, absolute health inequality related to the Socio-demographic Index (SDI) has decreased, as indicated by a reduction in DALY disparities between the most and least developed countries from -4,216.49 (95% CI: -4,558.27 to -3,874.71) in 1990 to -2,635.35 (95% CI: -2,868.40 to -2,402.30) in 2021. However, relative health inequality has worsened, with the relative disease burden in low-SDI countries increasing from -33.46% (95% CI: -36.29% to -30.63%) to -40.20% (95% CI: -44.02% to -36.39%). The burden of neonatal diseases remains disproportionately concentrated in low-SDI regions. Frontier analyses highlight opportunities for improvement across development levels. Some low-SDI countries have achieved minimal theoretical disease burdens, whereas certain high-SDI countries lag in reducing their neonatal disease burdens.

Conclusion

Over the past 32 years, the global burden of neonatal diseases attributable to LBW has significantly decreased, but inequality in disease burden has intensified. Addressing this disparity requires sustained international and governmental efforts to improve the accessibility, equality, and quality of healthcare for pregnant women and newborns.

Prenatal exposure to ambient air pollution and subsequent risk of lower respiratory tract infections in childhood and adolescence: A systematic review

BACKGROUND

Pregnancy represents a critical window of vulnerability to the harmful effects of air pollution on health. However, long-term consequences such as risk of having lower respiratory tract infections (LRTIs) are less explored. This systematic review aims to synthesize previous research on prenatal exposure to ambient (outdoor) air pollution and LRTIs in childhood and adolescence.

METHODS

We systematically searched Embase, MEDLINE, Web of Science Core Collection, CINAHL, and Global Health up to May 17, 2024. We included peer-reviewed publications of studies which investigated the association between prenatal exposure to ambient air pollution and LRTIs up to the age of 19. We excluded conference abstracts, study protocols, review articles, and grey literature. Screening and data extraction was conducted by two reviewers independently. We used the Office of Health Assessment and Translation tool to assess risk of bias and conducted a narrative synthesis.

RESULTS

The search yielded 6056 records, of which 16 publications describing 12 research studies were eligible for the synthesis. All studies were conducted in high- or upper-middle-income countries in Europe or Asia. Half (6) of the studies focused on LRTIs occurring within the first three years of life, and the others also included LRTIs in older children (up to age 14). Air pollutants investigated included nitrogen dioxide, sulphur dioxide, particulate matter (PM2.5: diameter ≤2.5 μm and PM10: diameter ≤10 μm), carbon monoxide, ozone, and benzene. Findings on a potential association between prenatal ambient air pollution exposure and LRTIs were inconclusive, without a clear and consistent direction. There was some suggestion of a positive association with prenatal PM2.5 exposure. The small number of studies identified, their poor geographical representation, and their methodological limitations including concerns for risk of bias preclude more definitive conclusions.

CONCLUSION

The available published evidence is insufficient to establish whether prenatal exposure to ambient air pollution increases risk of LRTIs in children and adolescents. With many populations exposed to high levels of air pollution, there is an urgent need for research in more diverse settings, more transparent reporting of methods, and exploring how, when, and for whom prenatal exposure to ambient air pollution leads to the greatest health risks.

PROSPERO REGISTRATION NUMBER

CRD42023407689.

Ambient air pollution exposure and adult asthma incidence: a systematic review and meta-analysis

BACKGROUND

Ambient (outdoor) air pollutant exposures have emerged as a plausible risk factor for incident childhood asthma. However, the effect of ambient air pollutant exposures on risk of incident adult asthma is unclear. We aimed to investigate associations between specific ambient air pollutants and the risk of incident adult asthma.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Web of Science from inception to Nov 27, 2023. We included observational studies with the outcome of new-onset asthma during adulthood (onset at ≥18 years), and metric of exposure of ambient air pollutants (particulate matter [PM]2·5, nitrogen dioxide [NO2], ozone [O3], and sulphur dioxide [SO2]). Study data were extracted independently by two reviewers and study quality was assessed using the Newcastle-Ottawa scale. When four or more eligible studies were available for a given pollutant, we applied meta-analysis using inverse variance weighting in a random effects model to estimate pooled relative risk (RR), and used meta-regression to explore sources of heterogeneity. The protocol was registered with PROSPERO, CRD42023420139.

FINDINGS

Our search identified 1891 references. After excluding 651 (34%) duplicates and ineligible studies, we included 25 studies in the systematic review. After excluding studies with overlapping populations or reporting effect estimates that could not be pooled, we performed meta-analysis for PM2·5 (nine studies), NO2 (nine studies), and O3 (four studies). Pooled random effects RRs for incident adult asthma per 5 μg/m3 increase in PM2·5 were 1·07 (95% CI 1·01 to 1·13) and per 10 μg/m3 in NO2 were 1·11 (1·03 to 1·20). We found no significant association between increasing O3 concentration and incident adult asthma (per 60-μg/m3 increase in O3, pooled RR 1·04 [0·79 to 1·36]). We found substantial heterogeneity across studies (I2=88% for all analyses). In exploratory meta-regression, average exposure level was a significant source of heterogeneity for the pooled NO2 estimate (95% CI -0·0077 to -0·0025 per μg/m3).

INTERPRETATION

Exposure to increased ambient PM2·5 or NO2 might present an additional risk factor for incident adult asthma, although high heterogeneity among included studies warrants caution in interpretation. Evidence was inconsistent for O3 and insufficient for SO2. To increase confidence and population representation in pooled estimates, further primary investigations are necessary, ideally with aligned methodology and reporting.

FUNDING

None.

Relationship between exposure to air pollutants in the first trimester and spontaneous abortion in pregnant women in the river valley city

Purpose The relationship between exposure doses of 2.5-micrometer Particulate Matter (PM2.5), Inhalable particles (PM10), Sulfur Dioxide (SO2), Nitrogen Dioxide (NO2) and Ozone (O3) in the first trimester and spontaneous abortion of pregnant women was evaluated by global average method and nearest monitoring station method, respectively. Method Retrospective analysis of the clinical data of pregnant women with spontaneous abortion and full-term pregnant women in the Department of Obstetrics and Gynecology of two third-class hospitals in a valley city in Northwest China. According to the age factor, the eligible pregnant women were matched at a ratio of 1 : 4. The global average method and the nearest monitoring station method were used to evaluate the exposure of pollutants. The rank-sum test and conditional logistic regression were used to analyze the correlation between air pollutants and spontaneous abortion. Results Although the global average method and the nearest monitoring station method are slightly different in the assessment of exposure dose, they do not affect the correlation evaluation with spontaneous abortion. The exposure of pregnant women to PM2.5(OR1 = 1.156, OR2 = 1.036), SO2 (OR1 = 1.432, OR2 = 1.429) and NO2 (OR1 = 1.121, OR2 = 1.159) in the first trimester is related to the occurrence of spontaneous abortion.(OR1: the global average method, OR2: the nearest monitoring station method) Conclusion The exposure of PM2.5, SO2 and NO2 in the first trimester in valley cities is associated with the occurrence of spontaneous abortion in pregnant women.

Health benefits of air pollution reduction: Evidence from economic slowdown in India

This paper evaluates health benefits associated with the impact of air pollution reduction on infant mortality in India. Leveraging plausibly exogenous geographic variation in air pollution due to the post-2010 economic slowdown-a period largely overlooked in the literature-I find that improvements in air quality resulted in a significant decline in infant mortality, particularly through respiratory diseases and biological pathways such as in utero and post-birth exposure. The associated health benefits correspond to 1338 saved infant lives, translating to monetary gains of $312.5 million. The paper advances our understanding of the link between air pollution and human health in settings with elevated air pollution and suboptimal regulatory frameworks.

TOLLIP and MUC5B modulate the effect of ambient NO2 on respiratory symptoms in infancy

BACKGROUND

Current knowledge suggests that the gene region containing MUC5B and TOLLIP plays a role in airway defence and airway inflammation, and hence respiratory disease. It is also known that exposure to air pollution increases susceptibility to respiratory disease. We aimed to study whether the effect of air pollutants on the immune response and respiratory symptoms in infants may be modified by polymorphisms in MUC5B and TOLLIP genes.

METHODS

359 healthy term infants from the prospective Basel-Bern Infant Lung Development (BILD) birth cohort were included in the study. The main outcome was the score of weekly assessed respiratory symptoms in the first year of life. Using the candidate gene approach, we selected 10 single nucleotide polymorphisms (SNPs) from the MUC5B and TOLLIP regions. Nitrogen dioxide (NO2) and particulate matter ≤10 μm in aerodynamic diameter (PM10) exposure was estimated on a weekly basis. We used generalised additive mixed models adjusted for known covariates. To validate our results in vitro, cells from a lung epithelial cell line were downregulated in TOLLIP expression and exposed to diesel particulate matter (DPM) and polyinosinic-polycytidylic acid.

RESULTS

Significant interaction was observed between modelled air pollution (weekly NO2 exposure) and 5 SNPs within MUC5B and TOLLIP genes regarding respiratory symptoms as outcome: E.g., infants carrying minor alleles of rs5744034, rs3793965 and rs3750920 (all TOLLIP) had an increased risk of respiratory symptoms with increasing NO2 exposure. In vitro experiments showed that cells downregulated for TOLLIP react differently to environmental pollutant exposure with DPM and viral stimulation.

CONCLUSION

Our findings suggest that the effect of air pollution on respiratory symptoms in infancy may be influenced by the genotype of specific SNPs from the MUC5B and TOLLIP regions. For validation of the findings, we provided in vitro evidence for the interaction of TOLLIP with air pollution.

Association of the external environmental exposome and obesity: A comprehensive nationwide study in 2019 among Chinese children and adolescents

OBJECTIVE

Children and adolescents are particularly vulnerable to the effects of various environmental factors, which could disrupt growth processes and potentially lead to obesity. Currently, comprehensive and systematic assessments of these environmental exposures during developmental periods are lacking. Therefore, this study aims to evaluate the association between external environmental exposures and the incidence of obesity in children and adolescents.

METHODS

Data was collected from the 2019 Chinese National Survey on Students' Constitution and Health, including 214,659 Han children aged 7 to 19. Body Mass Index (BMI) and BMI-for-age z-score (zBMI) were the metrics used to assess overweight and obesity prevalence. The study assessed 18 environmental factors, including air pollutants, natural space, land cover, meteorological conditions, built environment, road conditions, and artificial light at night. Exposome-wide association study (ExWAS) to analyze individual exposures' associations with health outcomes, and Weighted Quantile Sum (WQS) to assess cumulative exposure effects.

RESULTS

Among the children and adolescents, there were 24.2 % participants classified as overweight or obesity. Notably, 17 out of 18 environmental factors exhibited significant associations with zBMI and overweight/obesity. Seven air pollutants, road conditions, and built density were positively correlated with higher zBMI and obesity risk, while NDVI, forests, and meteorological factors showed negative correlations. Co-exposure analysis highlighted that SO2, ALAN, PM10, and trunk road density significantly increased zBMI, whereas rainfall, grassland, and forest exposure reduced it. Theoretically reduction in the number and prevalence of cases was calculated, indicating potential reductions in prevalence of up to 4.51 % for positive exposures and 5.09 % for negative exposures. Notably, substantial reductions were observed in regions with high pollution levels.

CONCLUSION

This large-scale investigation, encompassing various environmental exposures in schools, highlights the significant impact of air pollution, road characteristics, rainfall, and forest coverage on childhood obesity.

Placental DNA methylation signatures of prenatal air pollution exposure and potential effects on birth outcomes: an analysis of three prospective cohorts

BACKGROUND

Pregnancy air pollution exposure (PAPE) has been linked to a wide range of adverse birth and childhood outcomes, but there is a paucity of data on its influence on the placental epigenome, which can regulate the programming of physiological functions and affect child development. This study aimed to investigate the association between prenatal air pollutant exposure concentrations and changes in placental DNA methylation patterns, and to explore the potential windows of susceptibility and sex-specific alterations.

METHODS

This multi-site study used three prospective population-based mother-child cohorts: EDEN, PELAGIE, and SEPAGES, originating from four French geographical regions (Nancy, Poitiers, Brittany, and Grenoble). Pregnant women were included between 2003 and 2006 for EDEN and PELAGIE, and between 2014 and 2017 for SEPAGES. The main eligibility criteria were: being older than 18 years, having a singleton pregnancy, and living and planning to deliver in one of the maternity clinics in one of the study areas. A total of 1539 mother-child pairs were analysed, measuring placental DNA methylation using Illumina BeadChips. We used validated spatiotemporally resolved models to estimate PM2·5, PM10, and NO2 exposure over each trimester of pregnancy at the maternal residential address. We conducted a pooled adjusted epigenome-wide association study to identify differentially methylated 5'-C-phosphate-G-3' (CpG) sites and regions (assessed using the Infinium HumanMethylationEPIC BeadChip array, n=871), including sex-specific and sex-linked alterations, and independently validated our results (assessed using the Infinium HumanMethylation450 BeadChip array, n=668).

FINDINGS

We identified four CpGs and 28 regions associated with PAPE in the total population, 469 CpGs and 87 regions in male infants, and 150 CpGs and 66 regions in female infants. We validated 35% of the CpGs available. More than 30% of the identified CpGs were related to one (or more) birth outcome and most significant alterations were enriched for neural development, immunity, and metabolism related genes. The 28 regions identified for both sexes overlapped with imprinted genes (four genes), and were associated with neurodevelopment (nine genes), immune system (seven genes), and metabolism (five genes). Most associations were observed for the third trimester for female infants (134 of 150 CpGs), and throughout pregnancy (281 of 469 CpGs) and the first trimester (237 of 469 CpGs) for male infants.

INTERPRETATION

These findings highlight the molecular pathways through which PAPE might affect child health in a widespread and sex-specific manner, identifying the genes involved in the major physiological functions of a developing child. Further studies are needed to elucidate whether these epigenetic changes persist and affect health later in life.

FUNDING

French Agency for National Research, Fondation pour la Recherche Médicale, Fondation de France, and the Plan Cancer.

Mutual Associations of Exposure to Ambient Air Pollutants in the First 1000 Days of Life With Asthma/Wheezing in Children: Prospective Cohort Study in Guangzhou, China

BACKGROUND

The first 1000 days of life, encompassing pregnancy and the first 2 years after birth, represent a critical period for human health development. Despite this significance, there has been limited research into the associations between mixed exposure to air pollutants during this period and the development of asthma/wheezing in children. Furthermore, the finer sensitivity window of exposure during this crucial developmental phase remains unclear.

OBJECTIVE

This study aims to assess the relationships between prenatal and postnatal exposures to various ambient air pollutants (particulate matter 2.5 [PM2.5], carbon monoxide [CO], sulfur dioxide [SO2], nitrogen dioxide [NO2], and ozone [O3]) and the incidence of childhood asthma/wheezing. In addition, we aimed to pinpoint the potential sensitivity window during which air pollution exerts its effects.

METHODS

We conducted a prospective birth cohort study wherein pregnant women were recruited during early pregnancy and followed up along with their children. Information regarding maternal and child characteristics was collected through questionnaires during each round of investigation. Diagnosis of asthma/wheezing was obtained from children's medical records. In addition, maternal and child exposures to air pollutants (PM2.5 CO, SO2, NO2, and O3) were evaluated using a spatiotemporal land use regression model. To estimate the mutual associations of exposure to mixed air pollutants with the risk of asthma/wheezing in children, we used the quantile g-computation model.

RESULTS

In our study cohort of 3725 children, 392 (10.52%) were diagnosed with asthma/wheezing. After the follow-up period, the mean age of the children was 3.2 (SD 0.8) years, and a total of 14,982 person-years were successfully followed up for all study participants. We found that each quartile increase in exposure to mixed air pollutants (PM2.5, CO, SO2, NO2, and O3) during the second trimester of pregnancy was associated with an adjusted hazard ratio (HR) of 1.24 (95% CI 1.04-1.47). Notably, CO made the largest positive contribution (64.28%) to the mutual effect. After categorizing the exposure according to the embryonic respiratory development stages, we observed that each additional quartile of mixed exposure to air pollutants during the pseudoglandular and canalicular stages was associated with HRs of 1.24 (95% CI 1.03-1.51) and 1.23 (95% CI 1.01-1.51), respectively. Moreover, for the first year and first 2 years after birth, each quartile increment of exposure to mixed air pollutants was associated with HRs of 1.65 (95% CI 1.30-2.10) and 2.53 (95% CI 2.16-2.97), respectively. Notably, SO2 made the largest positive contribution in both phases, accounting for 50.30% and 74.70% of the association, respectively.

CONCLUSIONS

Exposure to elevated levels of mixed air pollutants during the first 1000 days of life appears to elevate the risk of childhood asthma/wheezing. Specifically, the second trimester, especially during the pseudoglandular and canalicular stages, and the initial 2 years after birth emerge as crucial susceptibility windows.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR-ROC-17013496; https://tinyurl.com/2ctufw8n.

Intrauterine and early postnatal exposures to submicron particulate matter and childhood allergic rhinitis: A multicity cross-sectional study in China

BACKGROUND

Airborne particulate matter pollution has been linked to occurrence of childhood allergic rhinitis (AR). However, the relationships between exposure to particulate matter with an aerodynamic diameter ≤1 μm (PM1) during early life (in utero and first year of life) and the onset of childhood AR remain largely unknown. This study aims to investigate potential associations of in utero and first-year exposures to size-segregated PMs, including PM1, PM1-2.5, PM2.5, PM2.5-10, and PM10, with childhood AR.

METHODS

We investigated 29286 preschool children aged 3-6 years in 7 Chinese major cities during 2019-2020 as the Phase II of the China Children, Families, Health Study. Machine learning-based space-time models were utilized to estimate early-life residential exposure to PM1, PM2.5, and PM10 at 1 × 1-km resolutions. The concentrations of PM1-2.5 and PM2.5-10 were calculated by subtracting PM1 from PM2.5 and PM2.5 from PM10, respectively. Multiple mixed-effects logistic models were used to assess the odds ratios (ORs) and 95% confidence intervals (CIs) of childhood AR associated with per 10-μg/m3 increase in exposure to particulate air pollution during in utero period and the first year of life.

RESULTS

Among the 29286 children surveyed (mean ± standard deviation, 4.9 ± 0.9 years), 3652 (12.5%) were reported to be diagnosed with AR. Average PM1 concentrations during in utero period and the first year since birth were 36.3 ± 8.6 μg/m3 and 33.1 ± 6.9 μg/m3, respectively. Exposure to PM1 and PM2.5 during pregnancy and the first year of life was associated with an increased risk of AR in children, and the OR estimates were higher for each 10-μg/m3 increase in PM1 than for PM2.5 (e.g., 1.132 [95% CI: 1.022-1.254] vs. 1.079 [95% CI: 1.014-1.149] in pregnancy; 1.151 [95% CI: 1.014-1.306] vs. 1.095 [95% CI: 1.008-1.189] in the first year of life). No associations were observed between AR and both pre- and post-natal exposure to PM1-2.5, indicating that PM1 rather than PM1-2.5 contributed to the association between PM2.5 and childhood AR. In trimester-stratified analysis, childhood AR was only found to be associated with exposure to PM1 (OR = 1.077, 95% CI: 1.027-1.128), PM2.5 (OR = 1.048, 95% CI: 1.018-1.078), and PM10 (OR = 1.032, 95% CI: 1.007-1.058) during the third trimester of pregnancy. Subgroup analysis suggested stronger PM-AR associations among younger (<5 years old) and winter-born children.

CONCLUSIONS

Prenatal and postnatal exposures to ambient PM1 and PM2.5 were associated with an increased risk of childhood AR, and PM2.5-related hazards could be predominantly attributed to PM1. These findings highlighted public health significance of formulating air quality guideline for ambient PM1 in mitigating children's AR burden caused by particulate air pollution.

Air pollution and childhood respiratory consultations in primary care: a systematic review

BACKGROUND

Outdoor air pollution is a known risk factor for respiratory morbidity worldwide. Compared with the adult population, there are fewer studies that analyse the association between short-term exposure to air pollution and respiratory morbidity in children in primary care.

OBJECTIVE

To evaluate whether children in a primary care setting exposed to outdoor air pollutants during short-term intervals are at increased risk of respiratory diagnoses.

METHODS

A search in Medline, the Cochrane Library, Web of Science and Embase databases throughout March 2023. Percentage change or risk ratios with corresponding 95% CI for the association between air pollutants and respiratory diseases were retrieved from individual studies. Risk of bias assessment was conducted with the Newcastle-Ottawa Scale (NOS) for cohort or case-control studies and an adjusted NOS for time series studies.

RESULTS

From 1366 studies, 14 were identified as meeting the inclusion criteria. Most studies had intermediate or high quality. A meta-analysis was not conducted due to heterogeneity in exposure and health outcome. Overall, studies on short-term exposure to air pollutants (carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2) and particulate matter ≤10 µm (PM10)) were associated with increased childhood respiratory consultations in primary care. In general, exposure to ozone was associated with a reduction in respiratory consultations.

CONCLUSIONS

The evidence suggests CO, SO2, NO2, PM10 and PM2.5 are risk factors for respiratory diseases in children in primary care in the short term. However, given the heterogeneity of the studies, interpretation of these findings must be done with caution.

PROSPERO REGISTRATION NUMBER

CRD42022259279.

The Climate Crisis and Breastfeeding: Opportunities for Resilience

The climate crisis is an emerging global challenge that poses potential risks to breastfeeding practices and outcomes. There are multifaceted effects of climate change affecting the breastfeeding dyad across environmental, societal, and human health dimensions. Breastfeeding support in the face of climate change will require solutions at the structural level-healthcare, community, and workplace settings-and at the mother-infant dyad level. Breastfeeding can additionally be an adaptive response to crisis situations and can mitigate some of the environmental challenges associated with climate change. Despite the undeniable significance of climate change on breastfeeding (and vice versa), our perspective as experts in the field is that this topic has not been systematically addressed. Although we highlight some of the challenges, potential solutions, and co-benefits of breastfeeding in the context of climate change, there are numerous issues that could be further explored and necessitate additional preparedness planning.

Effects of pre-natal and post-natal exposures to air pollution on onset and recurrence of childhood otitis media

BACKGROUND

Despite mounting evidence linking outdoor air pollution with otitis media (OM), the role of air pollutant(s) exposure during which critical window(s) on childhood OM remains unknown.

OBJECTIVES

We sought to identify the key air pollutant(s) and critical window(s) associated with the onset and recurrent attacks of OM in kindergarten children.

METHODS

A combined cross-sectional and retrospective cohort study involving 8689 preschoolers aged 3-6 years was performed in Changsha, China. From 2013-2020, data on air pollutants were collected from ambient air quality monitoring stations in Changsha, and the exposure concentration to each child at their home address was calculated using the inverse distance weighted (IDW) method. The relationship between air pollution and OM in kindergarten children was studied using multiple logistic regression models.

RESULTS

Childhood lifetime OM was associated with PM2.5, SO2 and NO2, with ORs (95% CI) of 1.43 (1.19-1.71), 1.18 (1.01-1.37) and 1.18 (1.00-1.39) by per IQR increase in utero exposure and with PM2.5, PM2.5-10 and PM10, with ORs = 1.15 (1.00-1.32), 1.25 (1.13-1.40) and 1.49 (1.28-1.74) for entire post-natal exposure, respectively. The 2nd trimester in utero and the post-natal period, especially the 1st year, were key exposure time windows to PM2.5 and PM10 associated with lifetime OM and the onset of OM. Similarly, the 4th gestational month was a critical window for all pollutants except CO exposure in relation to lifetime OM and OM onset, but not recurrent OM attacks. PM2.5 exposure during the nine gestational months and PM10 exposure during the first three years had cumulative effects on OM development. Our subgroup analysis revealed that certain children were more susceptible to the OM risk posed by air pollution.

CONCLUSIONS

Early-life exposure to air pollution, particularly PM2.5 during the middle of gestation and PM10 during the early post-natal period, was associated with childhood OM.