Open fire exposure increases the risk of pregnancy loss in South Asia

How climate change degrades child health: A systematic review and meta-analysis

BACKGROUND

Children are more vulnerable than adults to climate-related health threats, but reviews examining how climate change affects human health have been mainly descriptive and lack an assessment of the magnitude of health effects children face. This is the first systematic review and meta-analysis that identifies which climate-health relationships pose the greatest threats to children.

OBJECTIVES

We reviewed epidemiologic studies to analyse various child health outcomes due to climate change and identify the relationships with the largest effect size. We identify population-specific risks and provide recommendations for future research.

METHODS

We searched four large online databases for observational studies published up to 5 January 2023 following PRISMA (systematic review) guidelines. We evaluated each included study individually and aggregated relevant quantitative data. We used quantitative data in our meta-analysis, where we standardised effect sizes and compared them among different groupings of climate variables and health outcomes.

RESULTS

Of 1301 articles we identified, 163 studies were eligible for analysis. We identified many relationships between climate change and child health, the strongest of which was increasing risk (60 % on average) of preterm birth from exposure to temperature extremes. Respiratory disease, mortality, and morbidity, among others, were also influenced by climate changes. The effects of different air pollutants on health outcomes were considerably smaller compared to temperature effects, but with most (16/20 = 80 %) pollutant studies indicating at least a weak effect. Most studies occurred in high-income regions, but we found no geographical clustering according to health outcome, climate variable, or magnitude of risk. The following factors were protective of climate-related child-health threats: (i) economic stability and strength, (ii) access to quality healthcare, (iii) adequate infrastructure, and (iv) food security. Threats to these services vary by local geographical, climate, and socio-economic conditions. Children will have increased prevalence of disease due to anthropogenic climate change, and our quantification of the impact of various aspects of climate change on child health can contribute to the planning of mitigation that will improve the health of current and future generations.

Ambient air pollution and rate of spontaneous abortion

Spontaneous abortion (SAB), defined as a pregnancy loss before 20 weeks of gestation, affects up to 30% of conceptions, yet few modifiable risk factors have been identified. We estimated the effect of ambient air pollution exposure on SAB incidence in Pregnancy Study Online (PRESTO), a preconception cohort study of North American couples who were trying to conceive. Participants completed questionnaires at baseline, every 8 weeks during preconception follow-up, and in early and late pregnancy. We analyzed data on 4643 United States (U.S.) participants and 851 Canadian participants who enrolled during 2013-2019 and conceived during 12 months of follow-up. We used country-specific national spatiotemporal models to estimate concentrations of particulate matter <2.5 μm (PM2.5), nitrogen dioxide (NO2), and ozone (O3) during the preconception and prenatal periods at each participant's residential address. On follow-up and pregnancy questionnaires, participants reported information on pregnancy status, including SAB incidence and timing. We fit Cox proportional hazards regression models with gestational weeks as the time scale to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of time-varying prenatal concentrations of PM2.5, NO2, and O3 with rate of SAB, adjusting for individual- and neighborhood-level factors. Nineteen percent of pregnancies ended in SAB. Greater PM2.5 concentrations were associated with a higher incidence of SAB in Canada, but not in the U.S. (HRs for a 5 μg/m3 increase = 1.29, 95% CI: 0.99, 1.68 and 0.94, 95% CI: 0.83, 1.08, respectively). NO2 and O3 concentrations were not appreciably associated with SAB incidence. Results did not vary substantially by gestational weeks or season at risk. In summary, we found little evidence for an effect of residential ambient PM2.5, NO2, and O3 concentrations on SAB incidence in the U.S., but a moderate positive association of PM2.5 with SAB incidence in Canada.

Net benefit of smaller human populations to environmental integrity and individual health and wellbeing

Introduction

The global human population is still growing such that our collective enterprise is driving environmental catastrophe. Despite a decline in average population growth rate, we are still experiencing the highest annual increase of global human population size in the history of our species-averaging an additional 84 million people per year since 1990. No review to date has accumulated the available evidence describing the associations between increasing population and environmental decline, nor solutions for mitigating the problems arising.

Methods

We summarize the available evidence of the relationships between human population size and growth and environmental integrity, human prosperity and wellbeing, and climate change. We used PubMed, Google Scholar, and Web of Science to identify all relevant peer-reviewed and gray-literature sources examining the consequences of human population size and growth on the biosphere. We reviewed papers describing and quantifying the risks associated with population growth, especially relating to climate change.

Results

These risks are global in scale, such as greenhouse-gas emissions, climate disruption, pollution, loss of biodiversity, and spread of disease-all potentially catastrophic for human standards of living, health, and general wellbeing. The trends increasing the risks of global population growth are country development, demographics, maternal education, access to family planning, and child and maternal health.

Conclusion

Support for nations still going through a demographic transition is required to ensure progress occurs within planetary boundaries and promotes equity and human rights. Ensuring the wellbeing for all under this aim itself will lower population growth and further promote environmental sustainability.

Wildfire smoke exposure during pregnancy and perinatal, obstetric, and early childhood health outcomes: A systematic review and meta-analysis

BACKGROUND

Maternal exposure to air pollution during pregnancy is associated with adverse birth outcomes, although less is known for wildfire smoke. This systematic review evaluated the association between maternal exposure to wildfire smoke during pregnancy and the risk of perinatal, obstetric, and early childhood health outcomes.

METHODS

We searched CINAHL Complete, Ovid/EMBASE, Ovid/MEDLINE, ProQuest, PubMed, Scopus, Web of Science, and Google Scholar to identify relevant epidemiological observational studies indexed through September 2023. The screening of titles, abstracts, and full-texts, data extraction, and risk of bias assessment was performed by pairs of independent reviewers.

RESULTS

Our systematic search yielded 28,549 records. After duplicate removal, we screened 14,009 studies, identifying 31 for inclusion in the present review. Data extraction highlighted high methodological heterogeneity between studies, including a lack of geographic variation. Approximately 56.5% and 16% originated in the United States and Brazil, respectively, and fewer in other countries. Among the studies, wildfire smoke exposure during pregnancy was assessed using distance of residence from wildfire-affected areas (n = 15), measurement of air pollutant concentration during wildfires (n = 11), number of wildfire records (n = 3), aerosol index (n = 1), and geographic hot spots (n = 1). Pooled meta-analysis for birthweight and low birthweight were inconclusive, likely due to low number of methodologically homogenous studies. However, the reviewed studies provided suggestive evidence for an increased risk of birthweight reduction, low birthweight, preterm birth, and other adverse health outcomes.

CONCLUSIONS

This review identified 31 studies evaluating the impacts of maternal wildfire smoke exposure on maternal, infant, and child health. Although we found suggestive evidence of harm from exposure to wildfire smoke during pregnancy, more methodologically homogenous studies are required to enable future meta-analysis with greater statistical power to more accurately evaluate the association between maternal wildfire smoke and adverse birth outcomes and other health outcomes.

Quantifying evolution of soot mixing state from transboundary transport of biomass burning emissions

Incomplete combustion of fossil fuels and biomass burning emit large amounts of soot particles into the troposphere. The condensation process is considered to influence the size (Dp) and mixing state of soot particles, which affects their solar absorption efficiency and lifetimes. However, quantifying aging evolution of soot remains hampered in the real world because of complicated sources and observation technologies. In the Himalayas, we isolated soot sourced from transboundary transport of biomass burning and revealed soot aging mechanisms through microscopic observations. Most of coated soot particles stabilized one soot core under Dp < 400 nm, but 34.8% of them contained multi-soot cores (nsoot ≥ 2) and nsoot increased 3-9 times with increasing Dp. We established the soot mixing models to quantify transformation from condensation- to coagulation-dominant regime at Dp ≈ 400 nm. Studies provide essential references for adopting mixing rules and quantifying the optical absorption of soot in atmospheric models.

Stillbirths attributable to open fires and their geographic disparities in non-Western countries

Due to global warming, an increased number of open fires is becoming a major contributor to PM2.5 pollution and thus a threat to public health. However, the burden of stillbirths attributable to fire-sourced PM2.5 is unknown. In low- and middle-income countries (LMICs), there is a co-occurrence of high baseline stillbirth rates and frequent firestorms, which may lead to a geographic disparity. Across 54 LMICs, we conducted a self-matched case-control study, making stillbirths comparable to the corresponding livebirths in terms of time-invariant characteristics (e.g., genetics) and duration of gestational exposure. We established a joint-exposure-response function (JERF) by simultaneously associating stillbirth with fire- and non-fire-sourced PM2.5 concentrations, which were estimated by fusing multi-source data, such as chemical transport model simulations and satellite observations. During 2000-2014, 35,590 pregnancies were selected from multiple Demographic and Health Surveys. In each mother, a case of stillbirth was compared to her livebirth(s) based on gestational exposure to fire-sourced PM2.5. We further applied the JERF to assess stillbirths attributable to fire-sourced PM2.5 in 136 non-Western countries. The disparity was evaluated using the Gini index. The risk of stillbirth increased by 17.4% (95% confidence interval [CI]: 1.6-35.7%) per 10 μg/m3 increase in fire-sourced PM2.5. In 2014, referring to a minimum-risk exposure level of 10 μg/m3, total and fire-sourced PM2.5 contributed to 922,860 (95% CI: 578,451-1,183,720) and 49,951 (95% CI: 3,634-92,629) stillbirths, of which 10% were clustered within the 6.4% and 0.6% highest-exposure pregnancies, respectively. The Gini index of stillbirths attributable to fire-sourced PM2.5 was 0.65, much higher than for total PM2.5 (0.28). Protecting pregnant women against PM2.5 exposure during wildfires is critical to avoid stillbirths, as the burden of fire-associated stillbirths leads to a geographic disparity in maternal health.

Estimating the exposure-response function between long-term ozone exposure and under-5 mortality in 55 low-income and middle-income countries: a retrospective, multicentre, epidemiological study

BACKGROUND

In 2021, WHO suggested new target concentration limits for long-term exposure to ambient ozone. However, the harmful effects of ozone on vulnerable children have not been sufficiently studied. We aimed to evaluate the association between long-term ozone exposure and mortality in children younger than 5 years (hereafter denoted under-5 mortality) in low-income and middle-income countries (LMICs) and to estimate this mortality burden for 97 LMICs.

METHODS

By combining information from 128 Demographic and Health Surveys, we evaluated the association between the survival status of more than 1·2 million children younger than 5 years from 2457 sampling strata in 55 LMICs and the average peak-season ozone concentration during the life course, using a fixed-effects Cox model. A non-linear exposure-response function was developed by integrating the marginal effects of within-strata variation in exposure. We extrapolated the function obtained from the 55 LMICs to estimate the under-5 mortality burden attributable to ozone exposure in 97 LMICs, in which more than 95% of global deaths in this age group occur.

FINDINGS

The fixed-effects model showed a robust association between ozone and under-5 mortality. According to the fully adjusted linear model, an increment of 10 ppb in the life-course average peak-season ozone concentration was associated with a 6·4% (95% CI 2·4-10·7) increase in the risk of under-5 mortality. The non-linear exposure-response function showed a sublinear curvature with a threshold, suggesting that the effect of ozone exposure was non-significant at concentrations lower than the first-stage interim target (100 μg/m3) recommended by WHO. Using this function, we estimate that, in 2010, long-term ozone exposure contributed to 153 361 (95% CI 17 077-276 768; 2·3% [0·3-4·1]) deaths of children younger than 5 years in 97 LMICs, which is equivalent to 56·8% of all ozone-related deaths in adults (269 785) in these countries. From 2003 to 2017, the ozone-related under-5 mortality burden decreased in most of the 97 LMICs.

INTERPRETATION

Long-term exposure to ozone concentrations higher than the WHO first-stage interim target is a risk factor for under-5 mortality, and ozone exposure contributes substantially to mortality in this age group in LMICs. Increased efforts should be made to control ambient ozone pollution as this will lead to positive health benefits.

FUNDING

Ministry of Science and Technology of the People's Republic of China and China National Natural Science Foundation.

Global biomass fires and infant mortality

Global outdoor biomass burning is a major contributor to air pollution, especially in low- and middle-income countries. Recent years have witnessed substantial changes in the extent of biomass burning, including large declines in Africa. However, direct evidence of the contribution of biomass burning to global health outcomes remains limited. Here, we use georeferenced data on more than 2 million births matched to satellite-derived burned area exposure to estimate the burden of biomass fires on infant mortality. We find that each additional square kilometer of burning is associated with nearly 2% higher infant mortality in nearby downwind locations. The share of infant deaths attributable to biomass fires has increased over time due to the rapid decline in other important causes of infant death. Applying our model estimates across harmonized district-level data covering 98% of global infant deaths, we find that exposure to outdoor biomass burning was associated with nearly 130,000 additional infant deaths per year globally over our 2004 to 2018 study period. Despite the observed decline in biomass burning in Africa, nearly 75% of global infant deaths due to burning still occur in Africa. While fully eliminating biomass burning is unlikely, we estimate that even achievable reductions-equivalent to the lowest observed annual burning in each location during our study period-could have avoided more than 70,000 infant deaths per year globally since 2004.

Leveraging electronic health records to identify risk factors for recurrent pregnancy loss across two medical centers: a case-control study

Recurrent pregnancy loss (RPL), defined as 2 or more pregnancy losses, affects 5-6% of ever-pregnant individuals. Approximately half of these cases have no identifiable explanation. To generate hypotheses about RPL etiologies, we implemented a case-control study comparing the history of over 1,600 diagnoses between RPL and live-birth patients, leveraging the University of California San Francisco (UCSF) and Stanford University electronic health record databases. In total, our study included 8,496 RPL (UCSF: 3,840, Stanford: 4,656) and 53,278 Control (UCSF: 17,259, Stanford: 36,019) patients. Menstrual abnormalities and infertility-associated diagnoses were significantly positively associated with RPL in both medical centers. Age-stratified analysis revealed that the majority of RPL-associated diagnoses had higher odds ratios for patients <35 compared with 35+ patients. While Stanford results were sensitive to control for healthcare utilization, UCSF results were stable across analyses with and without utilization. Intersecting significant results between medical centers was an effective filter to identify associations that are robust across center-specific utilization patterns.

Landscape fire smoke enhances the association between fine particulate matter exposure and acute respiratory infection among children under 5 years of age: Findings of a case-crossover study for 48 low- and middle-income countries

BACKGROUND

Fine particulate matter (PM2.5) produced by landscape fires is thought to be more toxic than that from non-fire sources. However, the effects of "fire-sourced" PM2.5 on acute respiratory infection (ARI) are unknown.

METHODS

We combined Demographic and Health Survey (DHS) data from 48 countries with gridded global estimates of PM2.5 concentrations from 2003 to 2014. The proportions of fire-sourced PM2.5 were assessed by a chemical transport model using a variety of PM2.5 source data. We tested for associations between ARI and short-term exposure to fire- and "non-fire-sourced" PM2.5 using a bidirectional case-crossover analysis. The robustness and homogeneity of the associations were examined by sensitivity analyses. We also established a nonlinear exposure-response relationship between fire- and non-fire-sourced PM2.5 and ARI using a two-dimensional spline function.

RESULTS

The study included 36,432 children under 5 years who reported ARI symptoms. Each 1 µg/m3 increment of fire-sourced PM2.5 was associated with a 3.2 % (95 % confidence interval [CI] 0.2, 6.2) increment in the risk of ARI. This effect was comparable to that of each ∼5 µg/m3 increment in PM2.5 from non-fire sources (3.1 %; 95 % CI 2.4, 3.7). The association between ARI and total PM2.5 concentration was significantly mediated by the proportion of fire-sourced particles. Nonlinear analysis showed that the risk of ARI was increased by both fire- and non-fire-sourced PM2.5, but especially by the former.

CONCLUSIONS

PM2.5 produced by landscape fire was more strongly associated to ARI among children under 5 years than that from non-fire sources.

Estimation of stillbirths attributable to ambient fine particles in 137 countries

Gestational exposure to ambient fine particles (PM_2.5) increases the risk of stillbirth, but the related disease burden is unknown, particularly in low- and middle-income countries (LMICs). We combine state-of-the-art estimates on stillbirths, and multiple exposure-response functions obtained from previous meta-analyses or derived by a self-matched case-control study in 54 LMICs. 13,870 stillbirths and 32,449 livebirths are extracted from 113 geocoded surveys from the Demographic and Health Surveys. Each stillbirth is compared to livebirth(s) of the same mother using a conditional logit regression. We find that 10-µg/m³ increase of PM_2.5 is associated with an 11.0% (95% confidence interval [CI] 6.4, 15.7) increase in the risk of stillbirth, and the association is significantly enhanced by maternal age. Based on age-specific nonlinear PM_2.5-stillbirth curves, we evaluate the PM_2.5-related stillbirths in 137 countries. In 2015, of 2.09 (95% CI: 1.98, 2.20) million stillbirths, 0.83 (0.54, 1.08) million or 39.7% (26.1, 50.8) are attributable to PM_2.5 exposure exceeding the reference level of 10 μg/m³. In LMICs, preventing pregnant women from being exposed to PM_2.5 can improve maternal health.

Metal-Organic Frameworks and Their Composites for Environmental Applications

From the point of view of the ecological environment, contaminants such as heavy metal ions or toxic gases have caused harmful impacts on the environment and human health, and overcoming these adverse effects remains a serious and important task. Very recent, highly crystalline porous metal-organic frameworks (MOFs), with tailorable chemistry and excellent chemical stability, have shown promising properties in the field of removing various hazardous pollutants. This review concentrates on the recent progress of MOFs and MOF-based materials and their exploit in environmental applications, mainly including water treatment and gas storage and separation. Finally, challenges and trends of MOFs and MOF-based materials for future developments are discussed and explored.

Outdoor Air Pollution and Pregnancy Loss: a Review of Recent Literature

Purpose of Review

This review summarizes recent literature about the impacts of outdoor air pollution on pregnancy loss (spontaneous abortion/miscarriage and stillbirth), identifies challenges and opportunities, and provides recommendations for actions.

Recent Findings

Both short- and long-term exposures to ubiquitous air pollutants, including fine particulate matter < 2.5 and < 10 μm, may increase pregnancy loss risk. Windows of susceptibility include the entire gestational period, especially early pregnancy, and the week before event. Vulnerable subpopulations were not consistently explored, but some evidence suggests that pregnant parents from more disadvantaged populations may be more impacted even at the same exposure level.

Summary

Given environmental conditions conductive to high air pollution exposures become more prevalent as the climate shifts, air pollution’s impacts on pregnancy is expected to become a growing public health concern. While awaiting larger preconception studies to further understand causal impacts, multi-disciplinary efforts to minimize exposures among pregnant women are warranted.

Integrated single-cell RNA-seq and DNA methylation reveal the effects of air pollution in patients with recurrent spontaneous abortion

Background

Maternal air pollutants exposure is associated with a number of adverse pregnancy outcomes, including recurrent spontaneous abortion (RSA). However, the underlying mechanisms are still unknown. The present study aimed to understand the mechanism of RSA and its relationship with air pollution exposure. We compared data of decidual tissue from individuals with induced abortions and those with RSA by bulk RNA sequencing (RNA-seq), reduced representation bisulfite sequencing (RRBS), and single-cell RNA sequencing (scRNA-seq). Differentially expressed genes (DEGs) were verified using RT-qPCR and pyrosequencing. A logistic regression model was used to investigate the association between air pollutants exposure and RSA.

Results

We identified 98 DEGs with aberrant methylation by overlapping the RRBS and RNA-seq data. Nineteen immune cell subsets were identified. Compared with normal controls, NK cells and macrophages accounted for different proportions in the decidua of patients with RSA. We observed that the methylation and expression of IGF2BP1 were different between patients with RSA and controls. Furthermore, we observed significant positive associations between maternal air pollutants exposure during the year prior to pregnancy and in early pregnancy and the risk of RSA. Mediation analyses suggested that 24.5% of the effects of air pollution on the risk of RSA were mediated through IGF2BP1 methylation.

Conclusion

These findings reveal a comprehensive cellular and molecular mechanism of RSA and suggest that air pollution might cause pregnancy loss by affecting the methylation level of the IGF2BP1 promoter.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-022-01327-2.

The Effect of Particulate Matter Exposure During Pregnancy on Pregnancy and Child Health Outcomes in South Asia: Protocol for an Instrumental Variable Analysis

BACKGROUND

Determining the longer-term health effects of air pollution has been difficult owing to the multitude of potential confounding variables in the relationship between air pollution and health. Air pollution in many areas of South Asia is seasonal, with large spikes in particulate matter (PM) concentration occurring in the winter months. This study exploits this seasonal variation in PM concentration through a natural experiment.

OBJECTIVE

This project aims to determine the causal effect of PM exposure during pregnancy on pregnancy and child health outcomes.

METHODS

We will use an instrumental variable (IV) design whereby the estimated month of conception is our instrument for exposure to PM with a diameter less than 2.5 μm (PM2.5) during pregnancy. We will assess the plausibility of our assumption that timing of conception is exogenous with regard to our outcomes of interest and will adjust for date of monsoon onset to control for confounding variables related to harvest timing. Our outcomes are 1) birth weight, 2) pregnancy termination resulting in miscarriage, abortion, or still birth, 3) neonatal death, 4) infant death, and 5) child death. We will use data from the Demographic and Health Surveys (DHS) conducted in relevant regions of Bangladesh, India, Nepal, and Pakistan, along with monthly gridded data on PM2.5 concentration (0.1°×0.1° spatial resolution), precipitation data (0.5°×0.5° resolution), temperature data (0.5°×0.5°), and agricultural land use data (0.1°×0.1° resolution).

RESULTS

Data access to relevant DHSs was granted on June 6, 2021 for India, Nepal, Bangladesh, August 24, 2021 for Pakistan, and June 19 2022 for the latest DHS from India.

CONCLUSIONS

If the assumptions for a causal interpretation of our instrumental variable analysis are met, this analysis will provide important causal evidence on the maternal and child health effects of PM2.5 exposure during pregnancy. This evidence is important to inform personal behavior and interventions, such as the adoption of indoor air filtration during pregnancy as well as environmental and health policy.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/35249.

Gestational exposure to landscape fire increases under-5 child death via reducing birthweight: A risk assessment based on mediation analysis in low- and middle-income countries

BACKGROUND

Exposure to landscape fire smoke (LFS) is linked to child mortality and birthweight. It is unknown whether gestational exposure to LFS affects child survival rate. We aimed to link under-five death (U5D) to gestational LFS exposure by performing a causal mediation analysis based on birthweight.

METHOD

We conducted a sibling-matched case-control study of children under 5 years of age who were affiliated with the same mothers from Demographic and Health Surveys in 54 low- and middle-income countries, during the period from 2000 to 2014. LFS exposure was quantified as the surface concentration of fine particulate matter (PM_2.5) attributable to landscape fires, estimated using a global atmospheric model. Three pairwise associations between fire-sourced PM_2.5, birthweight, and U5D were assessed using fixed-effects regressions. We used a bootstrap-based mediation test of regression coefficients to examine whether the LFS-birthweight-U5D pathway was statistically significant. We also conducted three pairwise exposure-response functions using nonlinear models and used them to estimate the pathway-specific disease burden from 2000 to 2014.

RESULTS

After adjustments for multiple confounders, each 1-µg/m³ increase in gestational exposure to fire-sourced PM_2.5 was associated with a reduction of 2.179 (95% confidence interval [CI]: -3.777, -0.580) g in birthweight. Each 1-g birthweight reduction was associated with a 0.072% (95% CI: 0.065%, 0.078%) increase in U5D. Furthermore, each increase in exposure to fire-sourced PM_2.5 was associated with a 2.853% (95% CI: 0.835%, 4.911%) increase in U5D; 7.294% (95% CI: 0.710%, 24.254%) of the linkage was explained by LFS-attributable birthweight reduction. Based on the estimated exposure-response functions, from 2000 to 2014, global exposure to fire-sourced PM_2.5 contributed a mean birthweight reduction of 10.30 (95% CI: 2.93, 19.47) g, contributing to 60,350 (18,111, 106,619) premature U5Ds annually.

CONCLUSION

In low- and middle-income countries, gestational exposure to LFS can increase mortality during infancy; appropriate interventions are needed to promote health in childhood.

Source Sector Mitigation of Solar Energy Generation Losses Attributable to Particulate Matter Pollution

Particulate matter (PM) in the atmosphere and deposited on solar photovoltaic (PV) panels reduce PV energy generation. Reducing anthropogenic PM sources will therefore increase carbon-free energy generation and as a cobenefit will improve surface air quality. However, we lack a global understanding of the sectors that would be the most effective at achieving the necessary reductions in PM sources. Here we combine well-evaluated models of solar PV performance and atmospheric composition to show that deep cuts in air pollutant emissions from the residential, on-road, and energy sectors are the most effective approaches to mitigate PM-induced PV energy losses over East and South Asia, and the Tibetan Plateau, Central Asia, and the Arabian Peninsula, and Western Siberia, respectively. Using 2019 PV capacities as a baseline, we find that a 50% reduction in residential emissions would lead to an additional 10.3 TWh yr^-1 (US$878 million yr^-1) and 2.5 TWh yr^-1 (US$196 million yr^-1) produced in China and India, respectively.

Exposure to landscape fire smoke reduced birthweight in low- and middle-income countries: findings from a siblings-matched case-control study

Background:

Landscape fire smoke (LFS) has been associated with reduced birthweight, but evidence from low- and middle-income countries (LMICs) is rare.

Methods:

Here, we present a sibling-matched case–control study of 227,948 newborns to identify an association between fire-sourced fine particulate matter (PM_2.5) and birthweight in 54 LMICs from 2000 to 2014. We selected mothers from the geocoded Demographic and Health Survey with at least two children and valid birthweight records. Newborns affiliated with the same mother were defined as a family group. Gestational exposure to LFS was assessed in each newborn using the concentration of fire-sourced PM_2.5. We determined the associations of the within-group variations in LFS exposure with birthweight differences between matched siblings using a fixed-effects regression model. Additionally, we analyzed the binary outcomes of low birthweight (LBW) or very low birthweight (VLBW).

Results:

According to fully adjusted models, a 1 µg/m³ increase in the concentration of fire-sourced PM_2.5 was significantly associated with a 2.17 g (95% confidence interval [CI] 0.56–3.77) reduction in birthweight, a 2.80% (95% CI 0.97–4.66) increase in LBW risk, and an 11.68% (95% CI 3.59–20.40) increase in VLBW risk.

Conclusions:

Our findings indicate that gestational exposure to LFS harms fetal health.

Funding:

PKU-Baidu Fund, National Natural Science Foundation of China, Peking University Health Science Centre, and CAMS Innovation Fund for Medical Sciences.

Associations between exposure to landscape fire smoke and child mortality in low-income and middle-income countries: a matched case-control study

BACKGROUND

The prevalence of landscape fires has increased, particularly in low-income and middle-income countries (LMICs). We aimed to assess the impact of exposure to landscape fire smoke (LFS) on the health of children.

METHODS

We conducted a sibling-matched case-control study and selected 552 155 children (aged <18 years) from Demographic and Health Surveys in 55 LMICs from 2000 to 2014. Each deceased child was matched with their sibling(s). The exposure indicators were fire-sourced PM_2·5 and dry-matter emissions. We associated these exposure indicators with child mortality using conditional regressions, and derived an exposure-response function using a non-linear model. Based on the association, we quantified the global burden of fire-attributable child deaths in LMICs from 2000 to 2014.

FINDINGS

Each 1 μg/m³ increment of fire-sourced PM_2·5 was associated with a 2·31% (95% CI 1·50-3·13) increased risk of child mortality. The association was robust to different models. The exposure-response function was superlinear and suggested per-unit exposure to larger fires was more toxic. Based on our non-linear exposure-response function, we estimated that between 2000 and 2014, the five countries with the largest number of child deaths associated with fire-sourced PM_2·5 were Nigeria (164 000 [126 000 to 209 000] annual deaths), Democratic Republic of the Congo (126 000 [95% CI 114 000 to 139 000] annual deaths), India (65 900 [-22 200 to 147 000] annual deaths), Uganda (30 200 [24 500 to 36 300] annual deaths), and Indonesia (28 900 [19 100 to 38 400]).

INTERPRETATION

Exposure to landscape fire smoke contributes substantially to the global burden of child mortality.

FUNDING

National Natural Science Foundation of China, Ministry of Science and Technology of China, Peking University, UK National Institute for Health Research Health Protection Research Unit, Leverhulme Center for Wildfires, Environment and Society, and National Environment Research Council National Capability funding to National Centre for Earth Observation and Energy Foundation.

Association of maternal exposure to ambient particulate pollution with incident spontaneous pregnancy loss

BACKGROUND

Maternal exposure to ambient fine particulate matter (PM2.5) is a potential risk factor for pregnancy loss, but the extant findings are inconsistent. One reason for the inconsistency is the difficulty of distinguishing spontaneous from induced pregnancy losses, particularly in countries with planning policies.

OBJECTIVE

To examine the association between maternal PM2.5 exposure and spontaneous incident pregnancy loss in China.

METHODS

A total of 18,513 women of reproductive age was recruited from Jiangsu Province, China, in 2007. Among them, 2451 women reported 2613 valid records of incident pregnancies from 2007 to 2010. We used Cox regression to link the outcomes (live birth, spontaneous pregnancy loss, or induced abortion) of those incident pregnancies with maternal PM2.5 exposures, assessed using well-developed estimates of historical concentrations at the county level.

RESULTS

Among the 2613 incident pregnancies, 69 spontaneous pregnancy losses, 596 induced abortions, and 1948 live births occurred. According to the adjusted model, each 10-μg/m3 increment in the average PM2.5 concentration during pregnancy was associated with a 43.3% (95% confidence interval, 6.6-92.5%) increased probability of spontaneous pregnancy loss. Advanced maternal age, a potential competing risk factor, weakened the association between PM2.5 and spontaneous pregnancy loss. The association was nonsignificant for unintended pregnancies.

CONCLUSION

Maternal PM2.5 exposure was associated significantly with incident spontaneous pregnancy loss. Our findings provide insight into the harmful effect of air pollution on human reproduction.