Home environment and indoor air pollution exposure in an African birth cohort study

Sensitive periods for exposure to indoor air pollutants and psychosocial factors in association with symptoms of psychopathology at school-age in a South African birth cohort

Exposure to environmental toxicants and psychosocial stressors during gestation and early life are particularly harmful and may impact brain development. Specifically, exposure to indoor air pollutants (IAP) and psychosocial factors (PF) during these sensitive periods has been shown to predict childhood psychopathology. Here, we investigated sensitive periods for the individual and joint effects of IAP and PF on childhood psychopathology at 6.5 years. We analyzed data from the Drakenstein Child Health Study (N = 599). Exposure to IAP and PF was measured during the second trimester of pregnancy and 4 months postpartum. Childhood psychopathology was assessed at 6.5 years old using the Childhood Behavior Checklist (CBCL). We investigated individual effects of pre- and postnatal exposure to IAP and PF on CBCL scores using adjusted linear regression models, and joint effects of exposures using quantile g-computation and self-organizing maps (SOM). To identify possible sensitive periods, we used a structured life course modeling approach (SLCMA) as well as SOM. Prenatal exposure to IAP or PFs, and the total prenatal mixture assessed using quantile g-computation, were associated with increased psychopathology. SLCMA and SOM models also indicated that the prenatal period is a sensitive period for IAP exposure on childhood psychopathology. Depression and alcohol were associated in both the pre- and postnatal period. In conclusion, pregnancy may be a sensitive period for the effect of IAP on psychopathology. Exposure to maternal depression and alcohol in both periods was also associated with psychopathology. Determining sensitive periods of exposure is vital to ensure effective interventions to reduce psychopathology.

"The air within: reviewing the sources and health effects of indoor air pollution in households"

Air pollution in the interior of our homes is caused by diverse chemical, physical, and biological entities. This review comprehensively explores the current understanding of sources and health impacts of gaseous and particulate pollutants. Trend analysis of indoor air research worldwide revealed a quantum jump of 2.8 times in the number of publications during the last ten years. Indoor air pollutants are innumerable, but only a few are widely prevalent in most households. The qualitative complexity of pollutants translates to different health problems, including respiratory diseases, cardiovascular conditions, cancer, and deaths. There exist wide-scale disparities in the negative impacts among different economic strata, genders, and age groups; children and elderly populations are more vulnerable. In developing countries, pollutants primarily arise from traditional sources, whereas in developed countries, pollutants from non-conventional sources are comparatively significant. Only a few countries have indoor air regulations, policies, monitoring plans and effective enforcement.

Joint effects of indoor air pollution and maternal psychosocial factors during pregnancy on trajectories of early childhood psychopathology

Prenatal indoor air pollution and maternal psychosocial factors have been associated with adverse psychopathology. We used environmental-exposure mixture methodology to investigate joint effects of both exposure classes on child behavior trajectories. For 360 children from the South African Drakenstein Child Health Study, we created trajectories of Child Behavior Checklist scores (at 24, 42, and 60 months) using latent-class linear mixed effects models. Indoor air pollutants and psychosocial factors were measured during pregnancy (second trimester). After adjusting for confounding, single-exposure effects (per natural log-1 unit increase) were assessed using polytomous logistic regression models, joint effects using self-organizing maps, and principal component analysis. Three trajectories were chosen for both internalizing and externalizing problems, with "high" (externalizing) or "increasing" (internalizing) being the most adverse trajectories. High externalizing trajectory was associated with increased exposure to particulate matter of ≤ 10 microns in diameter (PM10) (odds ratio [OR] = 1.25; 95% CI, 1.01-1.55) and self-organizing maps exposure profile most associated with smoking (OR = 2.67; 95% CI, 1.14-6.27). Medium internalizing trajectory was associated with increased emotional intimate partner violence (OR = 2.66; 95% CI, 1.17-5.57), increasing trajectory with increased benzene (OR = 1.24; 95% CI, 1.02-1.51) and toluene (1.21; 95% CI, 1.02-1.44) and the principal component most correlated with benzene and toluene (OR = 1.25; 95% CI, 1.02-1.54). Prenatal exposure to environmental pollutants and psychosocial factors was associated with internalizing and externalizing child behavior trajectories. Understanding joint effects of adverse exposure mixtures will facilitate targeted interventions to prevent childhood psychopathology. This article is part of a Special Collection on Mental Health.

Joint effects of prenatal exposure to indoor air pollution and psychosocial factors on early life inflammation

It is hypothesized that air pollution and stress impact the central nervous system through neuroinflammatory pathways Despite this, the association between prenatal exposure to indoor air pollution and psychosocial factors on inflammatory markers in infancy has been underexplored in epidemiology studies. This study investigates the individual and joint effects of prenatal exposure to indoor air pollution and psychosocial factors on early life inflammation (interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α)). We analyzed data from the South African Drakenstein Child Health Study (N = 225). Indoor air pollution and psychosocial factor measurements were taken in the 2nd trimester of pregnancy. Circulating inflammatory markers (IL-1β, Il-6, and TNF-α) were measured in serum in the infants at 6 weeks postnatal. Linear regression models were used to investigate associations between individual exposures and inflammatory markers. To investigate joint effects of environmental and psychosocial factors, Self-Organizing Maps (SOM) were used to create exposure profile clusters. These clusters were added to linear regression models to investigate the associations between exposure profiles and inflammatory markers. All models were adjusted for maternal age, maternal HIV status, and ancestry to control for confounding. Most indoor air pollutants were positively associated with inflammatory markers, particularly benzene and TNF-α in single pollutant models. No consistent patterns were found for psychosocial factors in single-exposure linear regression models. In joint effects analyses, the SOM profile with high indoor air pollution, low SES, and high maternal depressive symptoms were associated with higher inflammation. Indoor air pollutants were consistently associated with increased inflammation in both individual and joint effects models, particularly in combination with low SES and maternal depressive symptoms. The trend for individual psychosocial factors was not as clear, with mainly null associations. As we have observed pro- and anti-inflammatory effects, future research should investigate joint effects of these exposures on inflammation and their health effects.

Harm from Residential Indoor Air Contaminants

This study presents a health-centered approach to quantify and compare the chronic harm caused by indoor air contaminants using disability-adjusted life-year (DALY). The aim is to understand the chronic harm caused by airborne contaminants in dwellings and identify the most harmful. Epidemiological and toxicological evidence of population morbidity and mortality is used to determine harm intensities, a metric of chronic harm per unit of contaminant concentration. Uncertainty is evaluated in the concentrations of 45 indoor air contaminants commonly found in dwellings. Chronic harm is estimated from the harm intensities and the concentrations. The most harmful contaminants in dwellings are PM2.5, PM10-2.5, NO2, formaldehyde, radon, and O3, accounting for over 99% of total median harm of 2200 DALYs/105 person/year. The chronic harm caused by all airborne contaminants in dwellings accounts for 7% of the total global burden from all diseases.

Investigating the association of prenatal psychological adversities with mother and child telomere length and neurodevelopment

BACKGROUND

Exposure to prenatal maternal psychological adversities can negatively affect the offspring's developing brain. Shortened telomere length (TL) has been implicated as a mechanism for the transgenerational effects of maternal psychological adversities on offspring. This study aimed to determine associations between prenatal psychological stressors and distress with maternal and early life TL, and associations between maternal, newborn and child TL with neurodevelopmental outcomes at 2 years of age.

METHODS

Follow-up TL was measured in a subgroup of African mothers (n = 138) and their newborns (n = 142) and children (n = 96) at 2-years in the Drakenstein Child Health Study. Prenatal symptoms of depression, distress, intimate partner violence, posttraumatic stress-disorder and childhood trauma were measured at 27 weeks gestation. Neurodevelopment was assessed at 2 years using the Bayley Scales of Infant and Toddler Development III. TLs were measured in whole bloods from mothers and their children at 2-years, and cord bloods in newborns.

RESULTS

Maternal prenatal stressors and distress were not significantly associated with TL in mothers or their children at birth or at 2-years. Furthermore, maternal psychological measures were not associated with early-life attrition of TL. Longer TL in children at 2-years was associated (p = 0.04) with higher motor functioning.

LIMITATIONS

Limited numbers of participants and single time-point psychological measures.

CONCLUSIONS

This study is the first to provide information on the association of early life TL with prenatal psychological adversities and neurodevelopmental outcomes in a population of low-income African mothers and their children.

Sensitive periods for exposure to indoor air pollutants and psychosocial factors in association with symptoms of psychopathology at school-age in a South African birth cohort

Background

Gestation and the first few months of life are important periods for brain development. During these periods, exposure to environmental toxicants and psychosocial stressors are particularly harmful and may impact brain development. Specifically, exposure to indoor air pollutants (IAP) and psychosocial factors (PF) during these sensitive periods has been shown to predict childhood psychopathology.

Objectives

This study aims to investigate sensitive periods for the individual and joint effects of IAP and PF on childhood psychopathology at 6.5 years.

Methods

We analyzed data from the Drakenstein Child Health Study (N=599), a South African birth cohort. Exposure to IAP and PF was measured during the second trimester of pregnancy and 4 months postpartum. The outcome of childhood psychopathology was assessed at 6.5 years old using the Childhood Behavior Checklist (CBCL). We investigated individual effects of either pre-or postnatal exposure to IAP and PF on CBCL scores using adjusted linear regression models, and joint effects of these exposures using quantile g-computation and self-organizing maps (SOM). To identify possible sensitive periods, we used a structured life course modeling approach (SLCMA) as well as exposure mixture methods (quantile g-computation and SOM).

Results

Prenatal exposure to IAP or PFs, as well as the total prenatal mixture assessed using quantile g-computation, were associated with increased psychopathology. SLCMA and SOM models also indicated that the prenatal period is a sensitive period for IAP exposure on childhood psychopathology. Depression and alcohol were associated in both the pre-and postnatal period, while CO was associated with the postnatal period.

Discussion

Pregnancy may be a sensitive period for the effect of indoor air pollution on childhood psychopathology. Exposure to maternal depression and alcohol in both periods was also associated with psychopathology. Determining sensitive periods of exposure is vital to ensure effective interventions to reduce childhood psychopathology.

Joint Effects of Indoor Air Pollution and Maternal Psychosocial Factors During Pregnancy on Trajectories of Early Childhood Psychopathology

Background

Prenatal indoor air pollution and maternal psychosocial factors have been associated with adverse psychopathology. We used environmental exposure mixture methodology to investigate joint effects of both exposure classes on child behavior trajectories.

Methods

For 360 children from the South African Drakenstein Child Health Study, we created trajectories of Child Behavior Checklist scores (24, 42, 60 months) using latent class linear mixed effects models. Indoor air pollutants and psychosocial factors were measured during pregnancy (2 nd trimester). After adjusting for confounding, single-exposure effects (per natural log-1 unit increase) were assessed using polytomous logistic regression models; joint effects using self-organizing maps (SOM), and principal component (PC) analysis.

Results

High externalizing trajectory was associated with increased particulate matter (PM 10 ) exposure (OR [95%-CI]: 1.25 [1.01,1.55]) and SOM exposure profile most associated with smoking (2.67 [1.14,6.27]). Medium internalizing trajectory was associated with increased emotional intimate partner violence (2.66 [1.17,5.57]), increasing trajectory with increased benzene (1.24 [1.02,1.51]) and toluene (1.21 [1.02,1.44]) and the PC most correlated with benzene and toluene (1.25 [1.02, 1.54]).

Conclusions

Prenatal exposure to environmental pollutants and psychosocial factors was associated with internalizing and externalizing child behavior trajectories. Understanding joint effects of adverse exposure mixtures will facilitate targeted interventions to prevent childhood psychopathology.

DNA methylation as a potential mediator of the association between indoor air pollution and neurodevelopmental delay in a South African birth cohort

BACKGROUND

Exposure to indoor air pollution during pregnancy has been linked to neurodevelopmental delay in toddlers. Epigenetic modification, particularly DNA methylation (DNAm), may explain this link. In this study, we employed three high-dimensional mediation analysis methods (HIMA, DACT, and gHMA) followed by causal mediation analysis to identify differentially methylated CpG sites and genes that mediate the association between indoor air pollution and neurodevelopmental delay. Analyses were performed using data from 142 mother to child pairs from a South African birth cohort, the Drakenstein Child Health Study. DNAm from cord blood was measured using the Infinium MethylationEPIC and HumanMethylation450 arrays. Neurodevelopment was assessed at age 2 years using the Bayley Scores of Infant and Toddler Development, 3rd edition across four domains (cognitive development, general adaptive behavior, language, and motor function). Particulate matter with an aerodynamic diameter of 10 μm or less (PM₁₀) was measured inside participants' homes during the second trimester of pregnancy.

RESULTS

A total of 29 CpG sites and 4 genes (GOPC, RP11-74K11.1, DYRK1A, RNMT) were identified as significant mediators of the association between PM₁₀ and cognitive neurodevelopment. The estimated proportion mediated (95%-confidence interval) ranged from 0.29 [0.01, 0.86] for cg00694520 to 0.54 [0.11, 1.56] for cg05023582.

CONCLUSIONS

Our findings suggest that DNAm may mediate the association between prenatal PM₁₀ exposure and cognitive neurodevelopment. DYRK1A and several genes that our CpG sites mapped to, including CNKSR1, IPO13, IFNGR1, LONP2, and CDH1, are associated with biological pathways implicated in cognitive neurodevelopment and three of our identified CpG sites (cg23560546 [DAPL1], cg22572779 [C6orf218], cg15000966 [NT5C]) have been previously associated with fetal brain development. These findings are novel and add to the limited literature investigating the relationship between indoor air pollution, DNAm, and neurodevelopment, particularly in low- and middle-income country settings and non-white populations.

Risk Factors of Severe COVID-19: A Review of Host, Viral and Environmental Factors

The clinical course and outcome of COVID-19 are highly variable, ranging from asymptomatic infections to severe disease and death. Understanding the risk factors of severe COVID-19 is relevant both in the clinical setting and at the epidemiological level. Here, we provide an overview of host, viral and environmental factors that have been shown or (in some cases) hypothesized to be associated with severe clinical outcomes. The factors considered in detail include the age and frailty, genetic polymorphisms, biological sex (and pregnancy), co- and superinfections, non-communicable comorbidities, immunological history, microbiota, and lifestyle of the patient; viral genetic variation and infecting dose; socioeconomic factors; and air pollution. For each category, we compile (sometimes conflicting) evidence for the association of the factor with COVID-19 outcomes (including the strength of the effect) and outline possible action mechanisms. We also discuss the complex interactions between the various risk factors.

Human exposure to indoor air pollution in Ethiopian households

Because most people spend the majority of their time in microenvironments, indoor air pollution (IAP) has gained more attention than outdoor air pollution recently. It is indeed crucial to understand IAP sources and the factors that influence human exposure. We synthesized evidence on IAP levels and contributing factors in Ethiopia from available literature, utilizing findings from 19 studies to retrieve 66 relevant values. Particulate matters (PM2.5, PM4, PM10, and TSP), as well as gaseous pollutants such as carbon monoxide (CO), nitrogen dioxide (NO2), polyaromatic hydrocarbons (PAHs), and total volatile organic compounds (TVOCs), were analyzed. The calculated mean concentrations for PM2.5, PM10, NO2, TVOCs, and CO were 477.47 μg/m3, 228.38 μg/m3, 63.84 μg/m3, 1361.79 μg/m3, and 18.82 ppm, respectively, all of which exceeded the annual WHO exposure guidelines. Geographical location, stove type, and household activities showed a variation in pollutants concentration. The higher levels of pollutants were attributed to emissions from biomass fuel used for baking injera, wot preparation, and conducting a coffee ceremony, as well as poor ventilation, season, cooking time, and tobacco smoke. The health risk assessments for exposure to various domestic activities were found to be acceptable, except for PM10, with the highest correlation with an acute respiratory infection. Although improved cookstove technology has been proposed as a sustainable energy source, investigations in Ethiopia have revealed that there is still room for public health protection. There is a paucity of research on the relationship between indoor and outdoor air pollution. Future research should prioritize these issues, with a focus on the link between IAP exposure and health effects. In conclusion, there is a higher IAP concentration in Ethiopia so the community should be made aware of it as well as related health effects, and immediate mitigation measures are needed to achieve a reduction in exposure.

DNA methylation as a potential mediator of the association between prenatal tobacco and alcohol exposure and child neurodevelopment in a South African birth cohort

Prenatal tobacco exposure (PTE) and prenatal alcohol exposure (PAE) have been associated with an increased risk of delayed neurodevelopment in children as well as differential newborn DNA methylation (DNAm). However, the biological mechanisms connecting PTE and PAE, DNAm, and neurodevelopment are largely unknown. Here we aim to determine whether differential DNAm mediates the association between PTE and PAE and neurodevelopment at 6 (N = 112) and 24 months (N = 184) in children from the South African Drakenstein Child Health Study. PTE and PAE were assessed antenatally using urine cotinine measurements and the ASSIST questionnaire, respectively. Cord blood DNAm was measured using the EPIC and 450 K BeadChips. Neurodevelopment (cognitive, language, motor, adaptive behavior, socioemotional) was measured using the Bayley Scales of Infant and Toddler Development, Third Edition. We constructed methylation risk scores (MRS) for PTE and PAE and conducted causal mediation analysis (CMA) with these MRS as mediators. Next, we conducted a high-dimensional mediation analysis to identify individual CpG sites as potential mediators, followed by a CMA to estimate the average causal mediation effects (ACME) and total effect (TE). PTE and PAE were associated with neurodevelopment at 6 but not at 24 months. PTE MRS reached a prediction accuracy (R2) of 0.23 but did not significantly mediate the association between PTE and neurodevelopment. PAE MRS was not predictive of PAE (R2 = 0.006). For PTE, 31 CpG sites and eight CpG sites were identified as significant mediators (ACME and TE P < 0.05) for the cognitive and motor domains at 6 months, respectively. For PAE, 16 CpG sites and 1 CpG site were significant mediators for the motor and adaptive behavior domains at 6 months, respectively. Several of the associated genes, including MAD1L1, CAMTA1, and ALDH1A2 have been implicated in neurodevelopmental delay, suggesting that differential DNAm may partly explain the biological mechanisms underlying the relationship between PTE and PAE and child neurodevelopment.

In-utero exposure to indoor air pollution or tobacco smoke and cognitive development in a South African birth cohort study

BACKGROUND AND AIMS

There is increasing evidence indicating that air pollution exposure is associated with neuronal damage. Since pregnancy is a critical window of vulnerability, air pollution exposure during this period could have adverse effects on neurodevelopment. This study aims 1) to analyze associations of prenatal exposure to indoor air pollution (particulate matter with diameters ≤10 μm, PM10) and tobacco smoke with neurodevelopment and 2) to determine whether these associations are mediated by deviations of epigenetic gestational age from chronological gestational age (ΔGA).

METHODS

Data of 734 children from the South African Drakenstein Child Health Study were analyzed. Prenatal PM10 exposure was measured using devices placed in the families' homes. Maternal smoking during pregnancy was determined by maternal urine cotinine measures. The Bayley Scales of Infant and Toddler Development III (BSID-III) was used to measure cognition, language and motor development and adaptive behavior at two years of age. Linear regression models adjusted for maternal age, gestational age, sex of child, ancestry, birth weight/length, and socioeconomic status were used to explore associations between air pollutants and BSID-III scores. A mediation analysis was conducted to analyze if these associations were mediated by ΔGA using DNA methylation measurements from cord blood.

RESULTS

An increase of one interquartile range in natural-log transformed PM10 (lnPM10; 1.58 μg/m3) was significantly associated with lower composite scores in cognition, language, and adaptive behavior sub-scores (composite score β-estimate [95%-confidence interval]: -0.950 [-1.821, -0.120]). Maternal smoking was significantly associated with lower adaptive behavior scores (-3.386 [-5.632, -1.139]). Associations were not significantly mediated by ΔGA (e.g., for PM10 and cognition, proportion mediated [p-value]: 4% [0.52]).

CONCLUSION

We found an association of prenatal exposure to indoor air pollution (PM10) and tobacco smoke on neurodevelopment at two years of age, particularly cognition, language, and adaptive behavior. Further research is needed to understand underlying biological mediators.

Indoor Household Exposures and Associated Morbidity and Mortality Outcomes in Children and Adults in South Africa

Human exposure to indoor pollution is one of the most well-established ways that housing affects health. We conducted a review to document evidence on the morbidity and mortality outcomes associated with indoor household exposures in children and adults in South Africa. The authors conducted a scientific review of the publicly available literature up to April 2022 using different search engines (PubMed, ProQuest, Science Direct, Scopus and Google Scholar) to identify the literature that assessed the link between indoor household exposures and morbidity and mortality outcomes in children and adults. A total of 16 studies with 16,920 participants were included. Bioaerosols, allergens, dampness, tobacco smoking, household cooking and heating fuels, particulate matter, gaseous pollutants and indoor spray residue play a significant role in different morbidity outcomes. These health outcomes include dental caries, asthma, tuberculosis, severe airway inflammation, airway blockage, wheeze, rhinitis, bronchial hyperresponsiveness, phlegm on the chest, current rhinoconjunctivitis, hay fever, poor early life immune function, hypertensive disorders of pregnancy, gestational hypertension, and increased incidence of nasopharyngeal bacteria, which may predispose people to lower respiratory tract infections. The findings of this research highlight the need for more initiatives, programs, strategies, and policies to better reduce the negative consequences of indoor household exposures.

Survey of residential indoor particulate matter measurements 1990-2019

We surveyed literature on measurements of indoor particulate matter in all size fractions, in residential environments free of solid fuel combustion (other than wood for recreation or space heating). Data from worldwide studies from 1990 to 2019 were assembled into the most comprehensive collection to date. Out of 2752 publications retrieved, 538 articles from 433 research projects met inclusion criteria and reported unique data, from which more than 2000 unique sets of indoor PM measurements were collected. Distributions of mean concentrations were compiled, weighted by study size. Long-term trends, the impact of non-smoking, air cleaners, and the influence of outdoor PM were also evaluated. Similar patterns of indoor PM distributions for North America and Europe could reflect similarities in the indoor environments of these regions. Greater observed variability for all regions of Asia may reflect greater heterogeneity in indoor conditions, but also low numbers of studies for some regions. Indoor PM concentrations of all size fractions were mostly stable over the survey period, with the exception of observed declines in PM2.5 in European and North American studies, and in PM10 in North America. While outdoor concentrations were correlated with indoor concentrations across studies, indoor concentrations had higher variability, illustrating a limitation of using outdoor measurements to approximate indoor PM exposures.

Assessing the External Exposome Using Wearable Passive Samplers and High-Resolution Mass Spectrometry among South African Children Participating in the VHEMBE Study

Children in low- and middle-income countries are often exposed to higher levels of chemicals and are more vulnerable to the health effects of air pollution. Little is known about the diversity, toxicity, and dynamics of airborne chemical exposures at the molecular level. We developed a workflow employing state-of-the-art wearable passive sampling technology coupled with high-resolution mass spectrometry to comprehensively measure 147 children's personal exposures to airborne chemicals in Limpopo, South Africa, as part of the Venda Health Examination of Mothers, Babies, and Their Environment (VHEMBE). 637 environmental exposures were detected, many of which have never been measured in this population; of these 50 airborne chemical exposures of concern were detected, including pesticides, plasticizers, organophosphates, dyes, combustion products, and perfumes. Biocides detected in wristbands included p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), propoxur, piperonyl butoxide, and triclosan. Exposures differed across the assessment period with 27% of detected chemicals observed to be either higher or lower in the wet or dry seasons.

Spatiotemporal variation in residential PM2.5 and PM10 concentrations in China: National on-site survey

BACKGROUND

Significant efforts have been directed toward addressing the adverse health effects of particulate matter, while few data exist to evaluate indoor exposure nationwide in China.

OBJECTIVES

This study aimed to investigate dwellings particulate matter levels in the twelve cities in China and provide large data support for policymakers to accelerate the legislative process.

METHODS

The current study was based on the CIEHS 2018 study and conducted in 12 cities of China. A total of 2128 air samples were collected from 610 residential households during the summer and winter. Both PM₁₀ and PM_2.5 were detected with a light-scattering dust meter in both the living room and bedroom. The Wilcoxon rank-sum test was performed to evaluate the correlations between PM_2.5 and PM₁₀ concentrations and both sampling season and site. Ratios of the living room to bedroom were calculated to evaluate the particulate matter variation between rooms. Hierarchical clustering was used to probe the question of whether the concentration varies between cities throughout China.

RESULTS

The geometric means of the PM_2.5 in living rooms and bedrooms were 39.80 and 36.55 μg/m³ in the summer, and 70.97 and 67.99 μg/m³ in the winter, respectively. In the summer, approximately 70 % of indoor dwelling PM_2.5 exceeded the limit of 25 μg/m³, and for PM₁₀ approximately 60 % of dwellings demonstrated levels higher than 50 μg/m³; the corresponding values were over 90 % and 80 % in winter, respectively. In Shijiazhuang, Lanzhou, Luoyang and Qingdao, the geometric means of the PM_2.5 concentrations were observed to be 1.5 to 4.3 times higher during winter than during summer; similar concentrations in summer and winter were observed in Harbin, Wuxi, and Shenzhen, while the PM_2.5 concentrations in Panjin were approximately 1.5 times higher in summer than in winter. There was no significant difference in particulate matter concentrations between the living rooms and bedrooms. Scatter plots showed that cities with low GDP and a small population had higher concentrations, while Shenzhen, which has a higher GDP and a large permanent population, had a relatively low concentration of particulate matter.

CONCLUSIONS

Our results suggest that indoor air pollution is a severe problem in China. It is necessary to continue monitoring indoor air quality to observe the changing trend under the tremendous effort of the Chinese government.

Predicting environmental risk factors in relation to health outcomes among school children from Romania using random forest model - An analysis of data from the SINPHONIE project

BACKGROUND

Few studies have simultaneously assessed the health impact of school and home environmental factors on children, since handling multiple highly correlated environmental variables is challenging. In this study, we examined indoor home and school environments in relation to health outcomes using machine learning methods and logistic regression.

METHODS

We used the data collected by the SINPHONIE (Schools Indoor Pollution and Health: Observatory Network in Europe) project in Romania, a multicenter European research study that collected comprehensive information on school and home environments, health symptoms in children, smoking, and school policies. The health outcomes were categorized as: any health symptoms, asthma, allergy and flu-like symptoms. Both logistic regression and random forest (RF) methods were used to predict the four categories of health outcomes, and the methods prediction performance was compared.

RESULTS

The RF method we employed for analysis showed that common risk factors for the investigated categories of health outcomes, included: environmental tobacco smoke (ETS), dampness in the indoor school environment, male gender, air freshener use, residence located in proximity of traffic (<200 m), stressful schoolwork, and classroom noise (contributions ranged from 7.91% to 23.12%). Specificity, accuracy and area under the curve (AUC) values for most outcomes were higher when using RF compared to logistic regression, while sensitivity was similar in both methods.

CONCLUSION

This study suggests that ETS, dampness in the indoor school environment, use of air fresheners, living in proximity to traffic (<200 m) and noise are common environmental risk factors for the investigated health outcomes. RF pointed out better predictive values, sensitivity and accuracy compared to logistic regression.

Biomarkers of Low-Level Environmental Exposure to Benzene and Oxidative DNA Damage in Primary School Children in Sardinia, Italy

Background: The main anthropic sources of exposure to airborne benzene include vehicular traffic, cigarette smoke, and industrial emissions. Methods: To detect early genotoxic effects of environmental exposure to benzene, we monitored environmental, personal, and indoor airborne benzene in children living in an urban area and an area near a petrochemical plant. We also used urinary benzene and S-phenylmercapturic acid (S-PMA) as biomarkers of benzene exposure and urinary 8-hydroxydeoxyguanosine (8-OHdG) as a biomarker of early genotoxic effects. Results: Although always below the European Union limit of 5 μg/m³, airborne benzene levels were more elevated in the indoor, outdoor, and personal samples from the industrial surroundings compared to the urban area (p = 0.026, p = 0.005, and p = 0.001, respectively). Children living in the surroundings of the petrochemical plant had urinary benzene values significantly higher than those from the urban area in both the morning and evening samples (p = 0.01 and p = 0.02, respectively). Results of multiple regression modelling showed that age was a significant predictor of 8-OHdG excretion, independent of the sampling hour. Moreover, at the low exposure level experienced by the children participating in this study, neither personal or indoor airborne benzene level, nor personal monitoring data, affected 8-OHdG excretion. Conclusions: Our results suggest the importance of biological monitoring of low-level environmental exposure and its relation to risk of genotoxic effects among children.

Indoor Exposure to Selected Air Pollutants in the Home Environment: A Systematic Review

(1) Background: There is increasing awareness that the quality of the indoor environment affects our health and well-being. Indoor air quality (IAQ) in particular has an impact on multiple health outcomes, including respiratory and cardiovascular illness, allergic symptoms, cancers, and premature mortality. (2) Methods: We carried out a global systematic literature review on indoor exposure to selected air pollutants associated with adverse health effects, and related household characteristics, seasonal influences and occupancy patterns. We screened records from six bibliographic databases: ABI/INFORM, Environment Abstracts, Pollution Abstracts, PubMed, ProQuest Biological and Health Professional, and Scopus. (3) Results: Information on indoor exposure levels and determinants, emission sources, and associated health effects was extracted from 141 studies from 29 countries. The most-studied pollutants were particulate matter (PM_2.5 and PM₁₀); nitrogen dioxide (NO₂); volatile organic compounds (VOCs) including benzene, toluene, xylenes and formaldehyde; and polycyclic aromatic hydrocarbons (PAHs) including naphthalene. Identified indoor PM_2.5 sources include smoking, cooking, heating, use of incense, candles, and insecticides, while cleaning, housework, presence of pets and movement of people were the main sources of coarse particles. Outdoor air is a major PM_2.5 source in rooms with natural ventilation in roadside households. Major sources of NO₂ indoors are unvented gas heaters and cookers. Predictors of indoor NO₂ are ventilation, season, and outdoor NO₂ levels. VOCs are emitted from a wide range of indoor and outdoor sources, including smoking, solvent use, renovations, and household products. Formaldehyde levels are higher in newer houses and in the presence of new furniture, while PAH levels are higher in smoking households. High indoor particulate matter, NO₂ and VOC levels were typically associated with respiratory symptoms, particularly asthma symptoms in children. (4) Conclusions: Household characteristics and occupant activities play a large role in indoor exposure, particularly cigarette smoking for PM_2.5, gas appliances for NO₂, and household products for VOCs and PAHs. Home location near high-traffic-density roads, redecoration, and small house size contribute to high indoor air pollution. In most studies, air exchange rates are negatively associated with indoor air pollution. These findings can inform interventions aiming to improve IAQ in residential properties in a variety of settings.

Exposure assessment of indoor particulate matter during pregnancy: a narrative review of the literature

OBJECTIVE

The aim of this review was to summarize the evidence of the exposure assessment approaches of indoor particulate matter (PM) during pregnancy and to recommend future focus areas.

CONTENT

Exposure to indoor PM during pregnancy is associated with adverse birth outcomes. However, many questions remain about the consistency of the findings and the magnitude of this effect. This may be due to the exposure assessment methods used and the challenges of characterizing exposure during pregnancy. Exposure is unlikely to remain constant over the nine-month period. Pregnant females' mobility and activities vary - for example, employment status may be random among females, but among those employed, activities are likely to be greater in the early pregnancy than closer to the delivery of the child.

SUMMARY

Forty three studies that used one of the five categories of indoor PM exposure assessment (self-reported, personal air monitoring, household air monitoring, exposure models and integrated approaches) were assessed. Our results indicate that each of these exposure assessment approaches has unique characteristics, strengths, and weaknesses. While questionnaires and interviews are based on self-report and recall, they were a major component in the reviewed exposure assessment studies. These studies predominantly used large sample sizes. Precision and detail were observed in studies that used integrated approaches (i. e. questionnaires, measurements and exposure models).

OUTLOOK

Given the limitations presented by these studies, exposure misclassification remains possible because of personal, within and between household variability, seasonal changes, and spatiotemporal variability during pregnancy. Therefore, using integrated approaches (i. e. questionnaire, measurements and exposure models) may provide better estimates of PM levels across trimesters. This may provide precision for exposure estimates in the exposure-response relationship.

Lung Health in Children in Sub-Saharan Africa: Addressing the Need for Cleaner Air

Air pollution is increasingly recognized as a global health emergency with its impacts being wide ranging, more so for low- and middle-income countries where both indoor and outdoor pollution levels are high. In Africa, more than 80% of children live in households which use unclean sources of energy. The effects of both indoor and outdoor pollution on lung health on children who are the most vulnerable to their effects range from acute lower respiratory tract infections to long-term chronic health effects. We reviewed the literature on the effects of air pollution in children in Sub-Saharan Africa from prenatal exposure, infancy and school-going children. Data from Sub-Saharan Africa on quantification of exposures both indoor and outdoor mainly utilizes modelling or self-reporting. Exposures to biomass not only increases the risk of acute respiratory tract infections in young children but also increases the risk of carriage of pathogenic bacteria in the upper respiratory tract. Although there is limited evidence of association between asthma and pollution in African children, airway hyper-responsiveness and lower lung function has been demonstrated in children with higher risk of exposure. Interventions at a policy level to both quantify the exposure levels at a population level are urgently needed to address the possible interventions to limit exposure and improve lung health in children in Sub-Saharan Africa.

Cardiovascular Effects of Indoor Air Pollution from Solid Fuel: Relevance to Sub-Saharan Africa

PURPOSE OF REVIEW

This research aims to summarize evidence on the cardiovascular effects of indoor air pollution (IAP) from solid fuel and identify areas for research and policy for low- and middle-income countries.

RECENT FINDINGS

IAP affects people from low socioeconomic status in Latin America, Asia, and Africa, who depend upon biomass as a fuel for cooking, heating, and lighting. In these settings, IAP disproportionately affects women, children, the elderly, and people with cardiopulmonary disease. The health effects of IAP include acute respiratory infections, chronic obstructive pulmonary disease, pneumoconiosis, cataract and blindness, pulmonary tuberculosis, adverse effects to pregnancy, cancer, and cardiovascular and cerebrovascular disease. New methods for assessing individual IAP exposure, exposing pathways of IAP-related cardiovascular disease, and performing qualitative research focusing on population preferences regarding strategies to reduce IAP exposure have been the most important developments in tackling the burden of IAP. Unfortunately, major disparities exist regarding research into the cardiovascular effects of IAP, with only few studies coming from sub-Saharan Africa, despite this region having the highest proportion of households using solid fuels. Premature cardiovascular deaths and disability can be averted in low-middle income countries by addressing biomass fuel usage by the most disadvantaged settings. While research is needed to uncover the mechanisms involved in cardiovascular outcomes linked to IAP, immediate action is needed to educate the most affected populations on IAP health hazards and to reduce their exposure to this environmental risk through promoting improved housing and better ventilation, as well as increasing access to affordable clean cooking energy.

Reductions in urinary metabolites of exposure to household air pollution in pregnant, rural Guatemalan women provided liquefied petroleum gas stoves

BACKGROUND

Household air pollution from solid fuels is a leading risk factor for morbidity and mortality worldwide. Pregnant women's exposure to polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs), two components of solid-fuel smoke, is associated with adverse birth outcomes. Even with improved solid-fuel stoves, exposure to PAHs and VOCs remains high. Therefore, cleaner cooking fuels need to be prioritized.

OBJECTIVE

We aimed to quantify exposure reduction to PAHs and VOCs among pregnant women in rural Guatemala with a liquefied petroleum gas (LPG) stove intervention.

MATERIALS AND METHODS

Urine from pregnant women (N = 50) was collected twice: at <20 weeks gestation, when women cooked exclusively with wood, and 6-8 weeks after receiving an LPG stove. Metabolites of four PAHs and eight VOCs were analyzed. Concurrent with urine collection, personal 48-h PM2.5 exposure was measured.

RESULTS

Women cooking exclusively with wood were exposed to high levels of particulate matter (PM2.5), which was reduced by 57% with the LPG stove. Urinary concentrations of total PAH metabolites (-37%), PMA (benzene metabolite; -49%), and CNEMA (acrylonitrile metabolite; -51%) were reduced. However, recent use of a wood-fired sauna bath led to large increases in excretion of urinary toxicant metabolites (+66-135%).

CONCLUSIONS

This is the first study to report PAH and VOC reductions from an LPG stove intervention introduced during pregnancy. However, other sources of air pollution minimized the gains seen from using an LPG stove. Thus, all sources of air pollution must be addressed in concert to reduce exposures to levels that protect health.

Genetic susceptibility to asthma increases the vulnerability to indoor air pollution

INTRODUCTION

Indoor air pollution and maternal smoking during pregnancy are associated with respiratory symptoms in infants, but little is known about the direct association with lung function or interactions with genetic risk factors. We examined associations of exposure to indoor particulate matter with a 50% cut-off aerodynamic diameter of 10 µm (PM₁₀) and maternal smoking with infant lung function and the role of gene-environment interactions.

METHODS

Data from the Drakenstein Child Health Study, a South African birth cohort, were analysed (n=270). Lung function was measured at 6 weeks and 1 year of age, and lower respiratory tract infection episodes were documented. We measured pre- and postnatal PM₁₀ exposures using devices placed in homes, and prenatal tobacco smoke exposure using maternal urine cotinine levels. Genetic risk scores determined from associations with childhood-onset asthma in the UK Biobank were used to investigate effect modifications.

RESULTS

Pre- and postnatal exposure to PM₁₀ as well as maternal smoking during pregnancy were associated with reduced lung function at 6 weeks and 1 year as well as with lower respiratory tract infection in the first year. Due to a significant interaction between the genetic risk score and prenatal exposure to PM₁₀, infants carrying more asthma-related risk alleles were more susceptible to PM₁₀-associated reduced lung function (p_interaction=0.007). This interaction was stronger in infants with Black African ancestry (p_interaction=0.001) and nonexistent in children with mixed ancestry (p_interaction=0.876).

CONCLUSIONS

PM₁₀ and maternal smoking exposures were associated with reduced lung function, with a higher susceptibility for infants with an adverse genetic predisposition for asthma that also depended on the infant's ancestry.

Environmental Health Research in Africa: Important Progress and Promising Opportunities

The World Health Organization in 2016 estimated that over 20% of the global disease burden and deaths were attributed to modifiable environmental factors. However, data clearly characterizing the impact of environmental exposures and health endpoints in African populations is limited. To describe recent progress and identify important research gaps, we reviewed literature on environmental health research in African populations over the last decade, as well as research incorporating both genomic and environmental factors. We queried PubMed for peer-reviewed research articles, reviews, or books examining environmental exposures and health outcomes in human populations in Africa. Searches utilized medical subheading (MeSH) terms for environmental exposure categories listed in the March 2018 US National Report on Human Exposure to Environmental Chemicals, which includes chemicals with worldwide distributions. Our search strategy retrieved 540 relevant publications, with studies evaluating health impacts of ambient air pollution (n=105), indoor air pollution (n = 166), heavy metals (n = 130), pesticides (n = 95), dietary mold (n = 61), indoor mold (n = 9), per- and polyfluoroalkyl substances (PFASs, n = 0), electronic waste (n = 9), environmental phenols (n = 4), flame retardants (n = 8), and phthalates (n = 3), where publications could belong to more than one exposure category. Only 23 publications characterized both environmental and genomic risk factors. Cardiovascular and respiratory health endpoints impacted by air pollution were comparable to observations in other countries. Air pollution exposures unique to Africa and some other resource limited settings were dust and specific occupational exposures. Literature describing harmful health effects of metals, pesticides, and dietary mold represented a context unique to Africa. Studies of exposures to phthalates, PFASs, phenols, and flame retardants were very limited. These results underscore the need for further focus on current and emerging environmental and chemical health risks as well as better integration of genomic and environmental factors in African research studies. Environmental exposures with distinct routes of exposure, unique co-exposures and co-morbidities, combined with the extensive genomic diversity in Africa may lead to the identification of novel mechanisms underlying complex disease and promising potential for translation to global public health.

Association between maternal psychological adversity and lung function in South African infants: A birth cohort study

OBJECTIVE

The association of perinatal psychological adversity (ie, stressors and distress) with infant lung function (ILF) and development is not well studied in Africa and elsewhere. We determined the association between maternal perinatal psychological adversity and ILF in African infants.

DESIGN

Prospective longitudinal follow up of the Drakenstein Child Health Study birth cohort.

PARTICIPANTS

Seven hundred and sixty-two infants aged 6 to 10 weeks and 485 infants who had data for both maternal perinatal psychological adversity and ILF (measured at 6 to 10 weeks and 12 months).

METHODS

The main analyses were based on cross-sectional measures of ILF at each assessment (6 to 10 weeks or 12 months), using generalized linear models, and then on the panel-data of both longitudinal ILF assessments, using generalised estimating equations, that allowed specification of the within-group correlation structure.

RESULTS

Prenatal intimate partner violence (IPV) exposure was associated with reduced respiratory resistance at 6 to 10 weeks (beta coefficient [β] = -.131, P = .023); postnatal IPV with reduced ratio of time to peak tidal expiratory flow over total expiratory time (tPTEF /tE ) at 12 months (β = -.206, P = .016); and prenatal depression with lower respiratory rate at 6 to 10 weeks (β = -.044, P = .032) and at 12 months (β = -.053, P = .021). Longitudinal analysis found an association of prenatal IPV with reduced tPTEF /tE (β = -.052, P < .0001); postnatal IPV with decreased functional residual capacity (FRC; β = -.086, P < .0001); prenatal posttraumatic stress disorder with increased FRC (β = .017, P < .0001); prenatal depression with increased FRC (β = .026, P < .0001) and postnatal depression with increased FRC (β = .021, P < .0001).

CONCLUSION

Screening for psychological adversity and understanding the mechanisms involved may help identify children at risk of altered lung development and inform approaches to treatment.

Risk and protective factors for child development: An observational South African birth cohort

BACKGROUND

Approximately 250 million (43%) children under the age of 5 years in low- and middle-income countries (LMICs) are failing to meet their developmental potential. Risk factors are recognised to contribute to this loss of human potential. Expanding understanding of the risks that lead to poor outcomes and which protective factors contribute to resilience in children may be critical to improving disparities.

METHODS AND FINDINGS

The Drakenstein Child Health Study is a population-based birth cohort in the Western Cape, South Africa. Pregnant women were enrolled between 20 and 28 weeks' gestation from two community clinics from 2012 to 2015; sociodemographic and psychosocial data were collected antenatally. Mothers and children were followed through birth until 2 years of age. Developmental assessments were conducted by trained assessors blinded to background, using the Bayley-III Scales of Infant and Toddler Development (BSID-III), validated for use in South Africa, at 24 months of age. The study assessed all available children at 24 months; however, some children were not able to attend, because of loss to follow-up or unavailability of a caregiver or child at the correct age. Of 1,143 live births, 1,002 were in follow-up at 24 months, and a total of 734 children (73%) had developmental assessments, of which 354 (48.2%) were girls. This sample was characterised by low household employment (n = 183; 24.9%) and household income (n = 287; 39.1% earning <R1,000 per month), and high prevalence of maternal psychosocial risk factors including alcohol use in pregnancy (n = 95; 14.5%), smoking (n = 241; 34.7%), depression (n = 156; 23.7%), lifetime intimate partner violence (n = 310; 47.3%), and history of maternal childhood trauma (n = 228; 34.7%). A high proportion of children were categorised as delayed (defined by scoring < -1 standard deviation below the mean scaled score calculated using the BSID-III norms from a United States population) in different domains (369 [50.5%] cognition, 402 [55.6%] receptive language, 389 [55.4%] expressive language, 169 [23.2%] fine motor, and 267 [38.4%] gross motor). Four hundred five (55.3%) children had >1 domain affected, and 75 (10.2%) had delay in all domains. Bivariate and multivariable analyses revealed several factors that were associated with developmental outcomes. These included protective factors (maternal education, higher birth weight, and socioeconomic status) and risk factors (maternal anaemia in pregnancy, depression or lifetime intimate partner violence, and maternal HIV infection). Boys consistently performed worse than girls (in cognition [β = -0.74; 95% CI -1.46 to -0.03, p = 0.042], receptive language [β = -1.10; 95% CI -1.70 to -0.49, p < 0.001], expressive language [β = -1.65; 95% CI -2.46 to -0.84, p < 0.001], and fine motor [β = -0.70; 95% CI -1.20 to -0.20, p = 0.006] scales). There was evidence that child sex interacted with risk and protective factors including birth weight, maternal anaemia in pregnancy, and socioeconomic factors. Important limitations of the study include attrition of sample from birth to assessment age and missing data in some exposure areas from those assessed.

CONCLUSIONS

This study provides reliable developmental data from a sub-Saharan African setting in a well-characterised sample of mother-child dyads. Our findings highlight not only the important protective effects of maternal education, birth weight, and socioeconomic status for developmental outcomes but also sex differences in developmental outcomes and key risk and protective factors for each group.

Personal NO2 and Volatile Organic Compounds Exposure Levels are Associated with Markers of Cardiovascular Risk in Women in the Cape Town Region of South Africa

Exposure to ambient NO2 and benzene, toluene ethyl-benzene and m+p- and o-xylenes (BTEX) is associated with adverse cardiovascular effects, but limited information is available on the effects of personal exposure to these compounds in South African populations. This 6-month follow-up study aims to determine 7-day personal ambient NO2 and BTEX exposure levels via compact passive diffusion samplers in female participants from Cape Town, and investigate whether exposure levels are associated with cardiovascular risk markers. Overall, the measured air pollutant exposure levels were lower compared to international standards. NO2 was positively associated with systolic and diastolic blood pressure (SBP and DBP), and inversely associated with the central retinal venular equivalent (CRVE) and mean baseline brachial artery diameter. o-xylene was associated with DBP and benzene was strongly associated with carotid intima media thickness (cIMT). Our findings showed that personal air pollution exposure, even at relatively low levels, was associated with several markers of cardiovascular risk in women residing in the Cape Town region.

Indoor air pollution and tobacco smoke exposure: impact on nasopharyngeal bacterial carriage in mothers and infants in an African birth cohort study

Indoor air pollution (IAP) or environmental tobacco smoke (ETS) exposure may influence nasopharyngeal carriage of bacterial species and development of lower respiratory tract infection (LRTI). The aim of this study was to longitudinally investigate the impact of antenatal or postnatal IAP/ETS exposure on nasopharyngeal bacteria in mothers and infants. A South African cohort study followed mother-infant pairs from birth through the first year. Nasopharyngeal swabs were taken at birth, 6 and 12 months for bacterial culture. Multivariable and multivariate Poisson regression investigated associations between nasopharyngeal bacterial species and IAP/ETS. IAP exposures (particulate matter, carbon monoxide, nitrogen dioxide, volatile organic compounds) were measured at home visits. ETS exposure was measured through maternal and infant urine cotinine. Infants received the 13-valent pneumococcal and Haemophilus influenzae B conjugate vaccines. There were 881 maternal and 2605 infant nasopharyngeal swabs. Antenatal ETS exposure was associated with Streptococcus pneumoniae carriage in mothers (adjusted risk ratio (aRR) 1.73 (95% CI 1.03-2.92)) while postnatal ETS exposure was associated with carriage in infants (aRR 1.14 (95% CI 1.00-1.30)) Postnatal particulate matter exposure was associated with the nasopharyngeal carriage of H. influenzae (aRR 1.68 (95% CI 1.10- 2.57)) or Moraxella catarrhalis (aRR 1.42 (95% CI 1.03-1.97)) in infants. Early-life environmental exposures are associated with an increased prevalence of specific nasopharyngeal bacteria during infancy, which may predispose to LRTI.

Environmental and behavioral determinants affecting the association of airway macrophages carbon load with distance to major roads and traffic density

Biomarkers are promising indicators to evaluate human exposure to air pollutants and to predict the health outcomes. Area of Airway macrophages that is occupied by Black Carbon could be used as a biomarker of personal long term exposure to traffic related air pollution. Association of airway macrophages carbon load with weighted average distance and environmental and subject-specific behavior are considered in this study. Sputum samples were taken from 160 healthy adult women and airway macrophages carbon load (AMCL) were determined in 93 subjects, which represent a success rate of 62% in sputum induction. Nearest distance of the subjects to major roads and average weighted distance were calculated for each subject. A questionnaire was field according to general and behavioral characteristics of the participants. There was not any significant difference (P-value >0.05) between induced and non-induced subjects. Subjects with indoor kitchen without separation wall, passive smokers and those with longer presence time in high traffic streets showed higher carbon area. Weighted average distance had a better association (β = -0.186, 95%CI: -0.139, -0.230, P-value = 0.00) with AMCL than nearest distance to major roads (β = -0.155, 95%CI: -0.109, -0.201, P-value = 0.19). Association of Weighted average distance with AMCL was interrupted in subjects with a garage connected to house environment, those with IK kitchen, those with a hood above the stove and passive smokers. The findings indicated that more generation and distribution of indoor air pollutants can completely enhance the internal exposure and indoor pollution has the same importance as outdoor pollution.

Indoor air pollution and exposure assessment of the gulf cooperation council countries: A critical review

Indoor air pollution is one of the human health threat problems in the Gulf Cooperation Council (GCC) countries. In these countries, due to unfavorable meteorological conditions, such as elevated ambient temperature, high relative humidity, and natural events such as dust storms, people spend a substantial amount of their time in indoor environments. In addition, production of physical and biological aerosols from air conditioners, cooking activities, burning of Arabian incense, and overcrowding due to pilgrimage programs are common causes of low quality indoor air in this region. Thus, due to infiltration of outdoor sources as well as various indoor sources, people living in the GCC countries are highly exposed to indoor air pollutants. Inhalation of indoor air pollutants causes mortalities and morbidities attributed to cardiorespiratory, pulmonary, and lung cancer diseases. Hence, the aim of this review study is to provide a summary of the major findings of indoor air pollution studies in different microenvironments in six GCC countries. These include characterization of detected indoor air pollutants, exposure concentration levels, source identifications, sustainable building designs and ventilation systems, and the mitigation strategies. To do so, >130 relevant indoor air pollution studies across the GCC countries were critically reviewed. Particulate matters (PM₁₀ and PM_2.5), total volatile organic compounds (TVOCs), carbon dioxide (CO₂), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and heavy metals were identified as the reported indoor air pollutants. Apart from them, indoor Radon and bioaerosols were studied only in specific GCC countries. Thus, future studies should also focus on the investigation of emerging indoor air pollutants, such as ultrafine and nanoparticles and their associated health effects. Furthermore, studies on the mitigation of indoor air pollution through the development of advanced air purification and ventilation systems could improve the indoor air quality (IAQ) in the GCC region.

Early-life exposure to indoor air pollution or tobacco smoke and lower respiratory tract illness and wheezing in African infants: a longitudinal birth cohort study

BACKGROUND

Indoor air pollution (IAP) and environmental tobacco smoke (ETS) are associated with lower respiratory tract illness (LRTI) or wheezing in children. However, the effect of the timing of these exposures, specifically antenatal versus postnatal, and of alternate fuel sources such as the increasingly used volatile organic compounds have not been well studied. We longitudinally investigated the effect of antenatal or postnatal IAP and ETS on LRTI or wheezing prevalence and severity in African infants.

METHODS

Mother and infant pairs enrolled over a 3-year period in a birth cohort study in two centres in Paarl, South Africa, were followed for the first year of life for LRTI or wheezing illness. We measured exposure to IAP (particulate matter, nitrogen dioxide, sulphur dioxide, carbon monoxide, and volatile organic compounds benzene and toluene) using devices placed in homes, antenatally and postnatally. We measured ETS longitudinally by maternal self-report and by urine cotinine measures. Study staff trained in recognition of LRTI or wheeze documented all episodes, which were categorised according to WHO case definition criteria. We used multivariate logistic and Poisson regressions to explore associations.

FINDINGS

Between March 1, 2012, and March 31, 2015, we enrolled 1137 mothers with 1143 livebirths. Of 1065 infants who attended at least one study visit, 524 episodes of LRTI occurred after discharge with a wheezing prevalence of 0·23 (95% CI 0·21-0·26) episodes per child year. Exposures associated with LRTI were antenatal maternal smoking (incidence rate ratio 1·62, 95% CI 1·14-2·30; p=0·004) or particulate matter (1·43, 1·06-1·95; p=0·008). Subanalyses of LRTI requiring hospitalisation (n=137) and supplemental oxygen (n=69) found antenatal toluene significantly increased the risk of LRTI-associated hospitalisation (odds ratio 5·13, 95% CI 1·43-18·36; p=0·012) and need for supplemental oxygen (13·21, 1·96-89·16; p=0·008). Wheezing illness was associated with both antenatal (incidence rate ratio 2·09, 95% CI 1·54-2·84; p<0·0001) and postnatal (1·27, 95% CI 1·03-1·56; p=0·024) maternal smoking. Antenatally, wheezing was associated with maternal passive smoke exposure (1·70, 1·25-2·31; p=0·001) and, postnatally, with any household member smoking (1·55, 1·17 -2·06; p=0·002).

INTERPRETATION

Antenatal exposures were the predominant risk factors associated with LRTI or wheezing illness. Toluene was a novel exposure associated with severe LRTI. Urgent and effective interventions focusing on antenatal environmental factors are required, including smoking cessation programmes targeting women of childbearing age pre-conception and pregnant women.

FUNDING

Bill & Melinda Gates Foundation, Discovery Foundation, South African Thoracic Society AstraZeneca Respiratory Fellowship, Medical Research Council South Africa, National Research Foundation South Africa, and CIDRI Clinical Fellowship.

The impact of prenatal exposure to air pollution on childhood wheezing and asthma: A systematic review

BACKGROUND AND OBJECTIVES

There has been no clear consensus about whether prenatal exposure to air pollution contributes to the development of wheezing and asthma in children. We conducted a systematic review to analyze the association between exposure to different pollutants during pregnancy and the development of childhood wheezing and asthma.

METHODS

We systematically reviewed epidemiological studies published through June 6, 2017 available in the MEDLINE and Web of Science databases. We included studies that examined the association between prenatal exposure to any air pollutants except tobacco smoke and the incidence or prevalence of "wheezing" or "asthma" from birth to 14 years of age. We extracted key characteristics of each included study using a template of predefined data items. We used the Critical Appraisal Skills Programme checklists to assess the validity of each included study. We conducted overall and subgroup meta-analyses for each summary exposure-outcome association. Pooled odds ratios (OR) with 95% confidence intervals (CI) were estimated by using a random effects model.

RESULTS

Eighteen studies met our eligibility criteria. There was notable variability in exposure assessment methods. The overall random effects risk estimates (95% CI) of different pollutants were 1.04 (0.94-1.15) aromatic hydrocarbons (PAH), 1.04 (1.01-1.07) NO₂, 1.4 (0.97-2.03) PM_2.5 for childhood wheeze and 1.07 (1.01-1.14) NO₂, 1 (0.97-1.03) PM_2.5, 1.02 (0.98-1.07) SO₂, 1.08 (1.05-1.12) PM₁₀ for childhood asthma. Minimal heterogeneity was seen for PAH and SO₂, while some heterogeneity was observed for PM₁₀, PM_2.5 and NO₂.

CONCLUSIONS

The overall and subgroup risk estimates from the meta-analyses showed statistically significant associations between prenatal exposures to NO₂, SO₂, and PM₁₀ and the risk of wheezing and asthma development in childhood. There is insufficient evidence to show an effect of prenatal exposure to BC, CO, and O₃ on childhood wheezing and asthma. Further studies are needed to examine the individual compounds' effects.

Bacterial and viral pneumonia: New insights from the Drakenstein Child Health Study

Pneumonia remains the major cause of childhood morbidity and mortality globally, despite improved preventative strategies. Increasing evidence also links early life pneumonia with the development of chronic non-communicable respiratory diseases into childhood and adulthood. The Drakenstein Child Health Study is a unique, multidisciplinary, South African birth cohort, investigating the incidence, risk factors, aetiology and long term impact of early life pneumonia on child health. The study provides novel data showing a high incidence of pneumonia despite excellent immunisation coverage; that pneumonia is due to multiple pathogens; that dysbiosis of the nasopharyngeal flora precedes and predisposes to pneumonia; and that early life pneumonia results in reduced lung function.

The association between environmental tobacco smoke exposure and childhood respiratory disease: a review

INTRODUCTION

Childhood respiratory illness is a major cause of morbidity and mortality particularly in low and middle-income countries. Environmental tobacco smoke (ETS) exposure is a recognised risk factor for both acute and chronic respiratory illness. Areas covered: The aim of this paper was to review the epidemiology of ETS exposure and impact on respiratory health in children. We conducted a search of 3 electronic databases of publications on ETS and childhood respiratory illness from 1990-2015. Key findings were that up to 70% of children are exposed to ETS globally, but under-reporting may mask the true prevalence. Maternal smoking and ETS exposure influence infant lung development and are associated with childhood upper and lower respiratory tract infection, wheezing or asthma. Further, exposure to ETS is associated with more severe respiratory disease. ETS exposure reduces lung function early in life, establishing an increased lifelong risk of poor lung health. Expert commentary: Urgent and effective strategies are needed to decrease ETS exposure in young children to improve child and long-term lung health in adults especially in low and middle income countries where ETS exposure is increasing.

Indoor air quality of low and middle income urban households in Durban, South Africa

INTRODUCTION

Elevated levels of indoor air pollutants may cause cardiopulmonary disease such as lower respiratory infection, chronic obstructive lung disease and lung cancer, but the association with tuberculosis (TB) is unclear. So far the risk estimates of TB infection or/and disease due to indoor air pollution (IAP) exposure are based on self-reported exposures rather than direct measurements of IAP, and these exposures have not been validated.

OBJECTIVE

The aim of this paper was to characterize and develop predictive models for concentrations of three air pollutants (PM₁₀, NO₂ and SO₂) in homes of children participating in a childhood TB study.

METHODS

Children younger than 15 years living within the eThekwini Municipality in South Africa were recruited for a childhood TB case control study. The homes of these children (n=246) were assessed using a walkthrough checklist, and in 114 of them monitoring of three indoor pollutants was also performed (sampling period: 24h for PM₁₀, and 2-3 weeks for NO₂ and SO₂). Linear regression models were used to predict PM₁₀ and NO₂ concentrations from household characteristics, and these models were validated using leave out one cross validation (LOOCV). SO₂ concentrations were not modeled as concentrations were very low.

RESULTS

Mean indoor concentrations of PM₁₀ (n=105)_, NO₂ (n=82) and SO₂ (n=82) were 64μg/m³ (range 6.6-241); 19μg/m³ (range 4.5-55) and 0.6μg/m³ (range 0.005-3.4) respectively with the distributions for all three pollutants being skewed to the right. Spearman correlations showed weak positive correlations between the three pollutants. The largest contributors to the PM₁₀ predictive model were type of housing structure (formal or informal), number of smokers in the household, and type of primary fuel used in the household. The NO₂ predictive model was influenced mostly by the primary fuel type and by distance from the major roadway. The coefficients of determination (R²) for the models were 0.41 for PM₁₀ and 0.31 for NO₂. Spearman correlations were significant between measured vs. predicted PM₁₀ and NO₂ with coefficients of 0.66 and 0.55 respectively.

CONCLUSION

Indoor PM₁₀ levels were relatively high in these households. Both PM₁₀ and NO₂ can be modeled with a reasonable validity and these predictive models can decrease the necessary number of direct measurements that are expensive and time consuming.

Exposure to polycyclic aromatic hydrocarbons and volatile organic compounds among recently pregnant rural Guatemalan women cooking and heating with solid fuels

BACKGROUND

Household air pollution is a major contributor to death and disability worldwide. Over 95% of rural Guatemalan households use woodstoves for cooking or heating. Woodsmoke contains carcinogenic or fetotoxic polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Increased PAHs and VOCs have been shown to increase levels of oxidative stress.

OBJECTIVE

We examined PAH and VOC exposures among recently pregnant rural Guatemalan women exposed to woodsmoke and compared exposures to levels seen occupationally or among smokers.

METHODS

Urine was collected from 23 women who were 3 months post-partum three times over 72h: morning (fasting), after lunch, and following dinner or use of wood-fired traditional sauna baths (samples=68). Creatinine-adjusted urinary concentrations of metabolites of four PAHs and eight VOCs were analyzed by liquid chromatography-mass spectrometry. Creatinine-adjusted urinary biomarkers of oxidative stress, 8-isoprostane and 8-OHdG, were analyzed using enzyme-linked immunosorbent assays (ELISA). Long-term (pregnancy through 3 months prenatal) exposure to particulate matter and airborne PAHs were measured.

RESULTS

Women using wood-fueled chimney stoves are exposed to high levels of particulate matter (median 48h PM2.5 105.7μg/m3; inter-quartile range (IQR): 77.6-130.4). Urinary PAH and VOC metabolites were significantly associated with woodsmoke exposures: 2-naphthol (median (IQR) in ng/mg creatinine: 295.9 (74.4-430.9) after sauna versus 23.9 (17.1-49.5) fasting; and acrolein: 571.7 (429.3-1040.7) after sauna versus 268.0 (178.3-398.6) fasting. Urinary PAH (total PAH: ρ=0.89, p<0.001) and VOC metabolites of benzene (ρ=0.80, p<0.001) and acrylonitrile (ρ=0.59, p<0.05) were strongly correlated with long-term exposure to particulate matter. However urinary biomarkers of oxidative stress were not correlated with particulate matter (ρ=0.01 to 0.05, p>0.85) or PAH and VOC biomarkers (ρ=-0.20 to 0.38, p>0.07). Urinary metabolite concentrations were significantly greater than those of heavy smokers (mean cigarettes/day=18) across all PAHs. In 15 (65%) women, maximum 1-hydroxypyrene concentrations exceeded the occupational exposure limit of coke-oven workers.

CONCLUSIONS

The high concentrations of urinary PAH and VOC metabolites among recently pregnant women is alarming given the detrimental fetal and neonatal effects of prenatal PAH exposure. As most women used chimney woodstoves, cleaner fuels are critically needed to reduce smoke exposure.

Determinants of early-life lung function in African infants

BACKGROUND

Low lung function in early life is associated with later respiratory illness. There is limited data on lung function in African infants despite a high prevalence of respiratory disease.

AIM

To assess the determinants of early lung function in African infants.

METHOD

Infants enrolled in a South African birth cohort, the Drakenstein child health study, had lung function measured at 6-10 weeks of age. Measurements, made with the infant breathing via a facemask during natural sleep, included tidal breathing, sulfur hexafluoride multiple breath washout and the forced oscillation technique. Information on antenatal and early postnatal exposures was collected using questionnaires and urine cotinine. Household benzene exposure was measured antenatally.

RESULTS

Successful tests were obtained in 645/675 (95%) infants, median (IQR) age of 51 (46-58) days. Infant size, age and male gender were associated with larger tidal volume. Infants whose mothers smoked had lower tidal volumes (-1.6 mL (95% CI -3.0 to -0.1), p=0.04) and higher lung clearance index (0.1 turnovers (95% CI 0.01 to 0.3), p=0.03) compared with infants unexposed to tobacco smoke. Infants exposed to alcohol in utero or household benzene had lower time to peak tidal expiratory flow over total expiratory time ratios, 10% (95% CI -15.4% to -3.7%), p=0.002) and 3.0% (95% CI -5.2% to -0.7%, p=0.01) lower respectively compared with unexposed infants. HIV-exposed infants had higher tidal volumes (1.7 mL (95% CI 0.06 to 3.3) p=0.04) compared with infants whose mothers were HIV negative.

CONCLUSION

We identified several factors including infant size, sex, maternal smoking, maternal alcohol, maternal HIV and household benzene associated with altered early lung function, many of which are factors amenable to public health interventions. Long-term study of lung function and respiratory disease in these children is a priority to develop strategies to strengthen child health.

Emission of volatile organic compounds from domestic coal stove with the actual alternation of flaming and smoldering combustion processes

Volatile organic compounds (VOCs) emissions from the chimney of a prevailing domestic stove fuelled with raw bituminous coal were measured under flaming and smoldering combustion processes in a farmer's house. The results indicated that the concentrations of VOCs quickly increased after the coal loading and achieved their peak values in a few minutes. The peak concentrations of the VOCs under the smoldering combustion process were significantly higher than those under the flaming combustion process. Alkanes accounted for the largest proportion (43.05%) under the smoldering combustion, followed by aromatics (28.86%), alkenes (21.91%), carbonyls (5.81%) and acetylene (0.37%). The emission factors of the total VOCs under the smoldering combustion processes (5402.9 ± 2031.8 mg kg^-1) were nearly one order of magnitude greater than those under the flaming combustion processes (559.2 ± 385.9 mg kg^-1). Based on the VOCs emission factors obtained in this study and the regional domestic coal consumption, the total VOCs emissions from domestic coal stoves was roughly estimated to be 1.25 × 10⁸ kg a^-1 in the Beijing-Tianjin-Hebei region.

Household indoor air quality and its associations with childhood asthma in Shanghai, China: On-site inspected methods and preliminary results

Few studies were conducted for associations of home environment with childhood health by on-site inspection in China. During 2013-2014, we conducted a case-control study with home inspection among 454 children (186 asthma children and 268 non-asthma children) in Shanghai, China. In this paper, we detailedly described the inspected methods and analyzed the preliminarily collected data. Except in winter, most residences meet the national standard for indoor temperature and relative humidity. Most living rooms had ≤1000ppm CO₂, whereas over half of the child's bedrooms had slightly >1000ppm CO₂ during night. Most residences had notably lower than 2500cfu/m³ airborne culturable fungi and ≤100μg/m³ formaldehyde. More than 70% of the child's bedrooms had ≤75μg/m³ PM_2.5 and ≤150μg/m³ PM₁₀. Indoor and outdoor concentrations of particulate matters had strong linear correlations (r=0.891-0.922; p-value <0.001). Most differences between cases and controls were not significant with respect to CO₂, culturable fungi, formaldehyde, and particulate matters. Before and after adjusted for potential confounders, indoor averaged concentration of CO₂ and particulate matters generally had negative associations with childhood history of doctor-diagnosed asthma in spring, summer, and autumn. Only in winter, indoor CO₂ concentration was significantly associated with the increased odds of childhood asthma. Our results indicated that air quality among most residences in Shanghai could meet the national standard for indoor air quality in warm seasons; but household air quality and ventilation status in winter should be greatly improved. We suspected that those "unexpected" negative associations could exist due to changes in lifestyle behaviors regarding indoor air quality after the child being diagnosed asthma by a doctor.

Exposure to the environmental endocrine disruptor TCDD and human reproductive dysfunction: Translating lessons from murine models

Humans and other animals are exposed to a wide array of man-made toxicants, many of which act as endocrine disruptors that exhibit differential effects across the lifespan. In humans, while the impact of adult exposure is known for some compounds, the potential consequences of developmental exposure to endocrine disrupting chemicals (EDCs) is more difficult to ascertain. Animal studies have revealed that exposure to EDCs prior to puberty can lead to adult reproductive disease and dysfunction. Specifically, in adult female mice with an early life exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), we demonstrated a transgenerational occurrence of several reproductive diseases that have been linked to endometriosis in women. Herein, we review the evidence for TCDD-associated development of adult reproductive disease as well as known epigenetic alterations associated with TCDD and/or endometriosis. We will also introduce new "Organ-on-Chip" models which, combined with our established murine model, are expected to further enhance our ability to examine alterations in gene-environment interactions that lead to heritable disease.

The Use of Sensory Analysis Techniques to Assess the Quality of Indoor Air

The quality of indoor air is one of the significant elements that influences people's well-being and health inside buildings. Emissions of pollutants, which may cause odor nuisance, are the main reason for people's complaints regarding the quality of indoor air. As a result, it is necessary to perform tests aimed at identifying the sources of odors inside buildings. The article contains basic information on the characteristics of the sources of indoor air pollution and the influence of the odor detection threshold on people's health and comfort. An attempt was also made to classify and use sensory analysis techniques to perform tests of the quality of indoor air, which would enable identification of sensory experience and would allow for indication of the degree of their intensity.

Aetiology of childhood pneumonia in a well vaccinated South African birth cohort: a nested case-control study of the Drakenstein Child Health Study

Background

Pneumonia is a leading cause of mortality and morbidity in children globally. The cause of pneumonia after introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) has not been well studied in low-income and middle-income countries, and most data are from cross-sectional studies of children admitted to hospital. We aimed to longitudinally investigate the incidence and causes of childhood pneumonia in a South African birth cohort.

Methods

We did a nested case-control study of children in the Drakenstein Child Health Study who developed pneumonia from May 29, 2012, to Dec 1, 2014. Children received immunisations including acellular pertussis vaccine and PCV13. A nested subgroup had nasopharyngeal swabs collected every 2 weeks throughout infancy. We identified pneumonia episodes and collected blood, nasopharyngeal swabs, and induced sputum specimens. We used multiplex real-time PCR to detect pathogens in nasopharyngeal swabs and induced sputum of pneumonia cases and in nasopharyngeal swabs of age-matched and site-matched controls. To show associations between organisms and pneumonia we used conditional logistic regression; results are presented as odds ratios (ORs) with 95% CIs.

Findings

314 pneumonia cases occurred (incidence of 0·27 episodes per child-year, 95% CI 0·24–0·31; median age 5 months [IQR 3–9]) in 967 children during 1145 child-years of follow-up. 60 (21%) cases of pneumonia were severe (incidence 0·05 episodes per child-year [95% CI 0·04–0·07]) with a case fatality ratio of 1% (three deaths). A median of five organisms (IQR 4–6) were detected in cases and controls with nasopharyngeal swabs, and a median of six organisms (4–7) recorded in induced sputum (p=0·48 compared with nasopharyngeal swabs). Bordetella pertussis (OR 11·08, 95% CI 1·33–92·54), respiratory syncytial virus (8·05, 4·21–15·38), or influenza virus (4·13, 2·06–8·26) were most strongly associated with pneumonia; bocavirus, adenovirus, parainfluenza virus, Haemophilus influenzae, and cytomegalovirus were also associated with pneumonia. In cases, testing of induced sputum in addition to nasopharyngeal swabs provided incremental yield for detection of B pertussis and several viruses.

Interpretation

Pneumonia remains common in this highly vaccinated population. Respiratory syncytial virus was the most frequently detected pathogen associated with pneumonia; influenza virus and B pertussis were also strongly associated with pneumonia. Testing of induced sputum increases the yield for detection of several organisms. New vaccines and strategies are needed to address the burden of childhood pneumonia.

Funding

10.13039/100000865Bill & Melinda Gates Foundation, 10.13039/501100001322Medical Research Council South Africa, 10.13039/501100001321National Research Foundation South Africa, 10.13039/100000002National Institute of Health, and H3Africa.