Black Carbon Exposure Research Articles

A novel in-situ method to determine the respiratory tract deposition of carbonaceous particles reveals dangers of public commuting in highly polluted megacity

BackgroundExposure to air pollutants is one of the major environmental health risks faced by populations globally. Information about inhaled particle deposition dose is crucial in establishing the dose–response function for assessing health-related effects due to exposure to air pollution.ObjectiveThis study aims to quantify the respiratory tract deposition (RTD) of equivalent black carbon (BC) particles in healthy young adults during a real-world commuting scenario, analyze factors affecting RTD of BC, and provide key parameters for the assessment of RTD.MethodsA novel in situ method was applied to experimentally determine the RTD of BC particles among subjects in the highly polluted megacity of Metro Manila, Philippines. Exposure measurements were made for 40 volunteers during public transport and walking.ResultsThe observed BC exposure concentration was up to 17-times higher than in developed regions. The deposition dose rate (DDR) of BC was up to 3 times higher during commute inside a public transport compared to walking (11.6 versus 4.4 μg hr−1, respectively). This is twice higher than reported in similar studies. The average BC mass deposition fraction (DF) was found to be 43 ± 16%, which can in large be described by individual factors and does not depend on gender.ConclusionsCommuting by open-sided public transport, commonly used in developing regions, poses a significant health risk due to acquiring extremely high doses of carcinogenic traffic-related pollutants. There is an urgent need to drastically update air pollution mitigation strategies for reduction of dangerously high emissions of BC in urban setting in developing regions. The presented mobile measurement set-up to determine respiratory tract deposition dose is a practical and cost-effective tool that can be used to investigate respiratory deposition in challenging environments.

Exposure Contrasts of Pregnant Women during the Household Air Pollution Intervention Network Randomized Controlled Trial.

Background:Exposure to arising from solid fuel combustion is estimated to result in million premature deaths and 91 million lost disability-adjusted life years annually. Interventions attempting to mitigate this burden have had limited success in reducing exposures to levels thought to provide substantive health benefits.Objectives:This paper reports exposure reductions achieved by a liquified petroleum gas (LPG) stove and fuel intervention for pregnant mothers in the Household Air Pollution Intervention Network (HAPIN) randomized controlled trial.Methods:The HAPIN trial included 3,195 households primarily using biomass for cooking in Guatemala, India, Peru, and Rwanda. Twenty-four-hour exposures to , carbon monoxide (CO), and black carbon (BC) were measured for pregnant women once before randomization into control () and LPG () arms and twice thereafter (aligned with trimester). Changes in exposure were estimated by directly comparing exposures between intervention and control arms and by using linear mixed-effect models to estimate the impact of the intervention on exposure levels.Results:Median postrandomization exposures of particulate matter (PM) with aerodynamic diameter () in the intervention arm were lower by 66% at the first (71.5 vs. ), and second follow-up visits (69.5 vs. ) compared to controls. BC exposures were lower in the intervention arm by 72% (9.7 vs. ) and 70% (9.6 vs. ) at the first and second follow-up visits, respectively, and carbon monoxide exposure was 82% lower at both visits (1.1 vs. ) in comparison with controls. Exposure reductions were consistent over time and were similar across research locations.Discussion:Postintervention exposures in the intervention arm were at the lower end of what has been reported for LPG and other clean fuel interventions, with 69% of samples falling below the World Health Organization Annual Interim Target 1 of . This study indicates that an LPG intervention can reduce exposures to levels at or below WHO targets. https://doi.org/10.1289/EHP10295

The impact of black carbon (BC) on mode-specific galvanic skin response (GSR) as a measure of stress in urban environments

Previous research has shown that walking and cycling could help alleviate stress in cities, however there is poor knowledge on how specific microenvironmental conditions encountered during daily journeys may lead to varying degrees of stress experienced at that moment. We use objectively measured data and a robust causal inference framework to address this gap. Using a Bayesian Doubly Robust (BDR) approach, we find that black carbon exposure statistically significantly increases stress, as measured by Galvanic Skin Response (GSR), while cycling and while walking. Augmented Outcome Regression (AOR) models indicate that greenspace exposure and the presence of walking or cycling infrastructure could reduce stress. None of these effects are statistically significant for people in motorized transport. These findings add to a growing evidence-base on health benefits of policies aimed at decreasing air pollution, improving active travel infrastructure and increasing greenspace in cities.

Black carbon health impacts in the Indo-Gangetic plain: Exposures, risks, and mitigation

A large discrepancy between simulated and observed black carbon (BC) surface concentrations over the densely populated Indo-Gangetic plain (IGP) has so far limited our ability to assess the magnitude of BC health impacts in terms of population exposure, morbidity, and mortality. We evaluate these impacts using an integrated modeling framework, including successfully predicted BC concentrations. Population exposure to BC is notable, with more than 60 million people identified as living in hotspots of BC concentration (wintertime mean, >20 μg m−3). The attributable fraction of the total cardiovascular disease mortality (CVM) burden to BC exposures is 62% for the megacity. The semiurban area comprised about 49% of the total BC-attributable CVM burden over the IGP. More than 400,000 lives can potentially be saved from CVM annually by implementing prioritized emission reduction from the combustion of domestic biofuel in the semiurban area, diesel oil in transportation, and coal in thermal power plant and brick kiln industries in megacities.

Factors affecting occupational black carbon exposure in enclosed railway stations

Many rail services around the world continue to use diesel as the primary fuel source and enclosed railway stations have been identified as a possible hotspot for exposure to harmful diesel exhaust exposures. Little is known about the occupational exposure to air pollution for railway station workers due to their mobility around the station and variations in station design. A detailed understanding of the concentration of black carbon (BC), a diesel exhaust tracer, inside railway stations and the factors driving occupational exposures is required to minimize occupational exposure. Real-time personal exposure to BC was measured during 60 work-shifts encompassing different roles at three large enclosed railway stations of different design in London, Birmingham and Edinburgh (UK). Sampling was conducted by the train station workers over a period of 27 days between January 2017 to October 2018. Worker shift-mean BC exposures ranged 0.6–20.8 μg m−3 but 1-min peak exposures reached 773 μg m−3, with train dispatchers experiencing the highest BC exposures. Station design, job role, and frequency of diesel trains were the main drivers of occupational BC exposure. Elevated exposures for some station workers indicate that mitigation measures to reduce their exposure should be implemented to lower the risk of occupational health impacts. These could include improving ventilation and reducing engine emissions.

Effect of time-activity patterns and microenvironments on the personal exposure of undergraduate students to black carbon

In this study, the personal exposure to and potential dose of black carbon (BC) of undergraduate students (22-27years old, nonsmokers) were determined. BC was continuously measured by a portable device (microAeth® AE51) for four consecutive days in Istanbul between April and May 2019. The time-activity diaries filled out by each volunteer were assessed to define the activities and microenvironments (home, school, transportation and entertainment) that contributed to daily BC exposure. The overall mean concentration of BC was 2.0μg/m3, and the mean concentrations on weekdays and weekends were 3.0μg/m3 and 1.1μg/m3, respectively. Transportation made the highest contribution to mean BC exposure (42%) and dose (45.8%) on weekdays, while the contributions of home-based activities to BC exposure (66.1%) and dose (63.2%) were higher on weekends. Students had the most intense exposure to (2.8% and 4.6%) and dose (3.1% and 5.8%) of BC in transportation both on weekdays and on weekends, respectively. Between transportation modes, the mean BC concentration was the highest for minibuses (14.8μg/m3), while walking made the largest contribution to BC exposure (16.8%) on weekdays. Students spent 12.8% of their weekdays at school, and the contributions of the school environment to BC exposure and dose were 8.5% and 7%, respectively. Exposure to BC increased during cooking and eating activities in microenvironments such as the kitchen, cafe and dining hall.

Acute ambulatory blood pressure response to short-term black carbon exposure: The MobiliSense sensor-based study

Documented relationships between black carbon (BC) exposure and blood pressure (BP) have been inconsistent. Very few studies measured both BC exposure and ambulatory BP across the multiple daily environments visited in the general population, and none adjusted for personal noise exposure, a major confounder. Our study addresses these gaps by considering 245 adults living in the Grand Paris region. Personal exposure to BC was monitored for 2 days using AE51 microaethalometers. Ambulatory BP was measured every 30 min after waking up using Arteriograph 24 monitors (n = 6772). Mixed effect models with a random intercept at the individual level and time-autocorrelation structure adjusted for personal noise exposure were used to evaluate the associations between BC exposure (averaged from 5 min to 1 h before each BP measurement) and BP. To increase the robustness of findings, we eliminated confounding by unmeasured time-invariant personal variables, by modelling the associations with fixed-effect models. All models were adjusted for potential confounders and short-term time trends. Results from mixed models show that a 1-μg/m3 increase in 5-minute averaged BC exposure was associated with an increase of 0.57 mmHg in ambulatory systolic blood pressure (SBP) (95 % CI: 0.30, 0.83) and with an increase of 0.36 mmHg in diastolic blood pressure (DBP) (95 % CI: 0.14, 0.58). The slope of the exposure-response relationship gradually decreased for both SBP and DBP with the increase in the averaging period of BC exposure from 5 min to 1 h preceding each BP measurement. Findings from the fixed-effect models were consistent with these results. There was no effect modification by noise in the associations, across all exposure windows. We found evidence of a relationship between BC exposure and acute increase in ambulatory SBP and DBP after adjustment for personal noise exposure, with potential implications for the development of adverse cardiovascular outcomes.

Effects of household and participant characteristics on personal exposure and kitchen concentration of fine particulate matter and black carbon in rural Honduras

Traditional cooking with solid fuels (biomass, animal dung, charcoals, coal) creates household air pollution that leads to millions of premature deaths and disability worldwide each year. Exposure to household air pollution is highest in low- and middle-income countries. Using data from a stepped-wedge randomized controlled trial of a cookstove intervention among 230 households in Honduras, we analyzed the impact of household and personal variables on repeated 24-h measurements of fine particulate matter (PM2.5) and black carbon (BC) exposure. Six measurements were collected approximately six-months apart over the course of the three-year study. Multivariable mixed models explained 37% of variation in personal PM2.5 exposure and 49% of variation in kitchen PM2.5 concentrations. Additionally, multivariable models explained 37% and 47% of variation in personal and kitchen BC concentrations, respectively. Stove type, season, presence of electricity, primary stove location, kitchen enclosure type, stove use time, and presence of kerosene for lighting were all associated with differences in geometric mean exposures. Stove type explained the most variability of the included variables. In future studies of household air pollution, tracking the cooking behaviors and daily activities of participants, including outdoor exposures, may explain exposure variation beyond the household and personal variables considered here.

Socioeconomic and Demographic Associations with Wintertime Air Pollution Exposures at Household, Community, and District Scales in Rural Beijing, China.

The Chinese government implemented a national household energy transition program that replaced residential coal heating stoves with electricity-powered heat pumps for space heating in northern China. As part of a baseline assessment of the program, this study investigated variability in personal air pollution exposures within villages and between villages and evaluated exposure patterns by sociodemographic factors. We randomly recruited 446 participants in 50 villages in four districts in rural Beijing and measured 24 h personal exposures to fine particulate matter (PM2.5) and black carbon (BC). The geometric mean personal exposure to PM2.5 and BC was 72 and 2.5 μg/m3, respectively. The variability in PM2.5 and BC exposures was greater within villages than between villages. Study participants who used traditional stoves as their dominant source of space heating were exposed to the highest levels of PM2.5 and BC. Wealthier households tended to burn more coal for space heating, whereas less wealthy households used more biomass. PM2.5 and BC exposures were almost uniformly distributed by socioeconomic status. Future work that combines these results with PM2.5 chemical composition analysis will shed light on whether air pollution source contributors (e.g., industrial, traffic, and household solid fuel burning) follow similar distributions.

Long-term exposure to ambient black carbon is associated with sleep disturbance in college students

BackgroundEvidence suggests an association of air pollution with sleep quality. However, there is limited knowledge regarding the effect of black carbon, a key component of ambient particulate matter, on sleep. ObjectivesTo investigate the association of long-term exposure to black carbon and sleep quality in a group of college students. MethodsA retrospective cohort study was conducted in five universities in different regions of China. The concentrations of black carbon and other environment factors were defined as the averages during the 6 years prior to the recruitment. Averagely daily dose of black carbon exposure was estimated according to the respiratory rate. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI) with a cutoff >5 indicating sleep disturbance. Linear regression and logistic regression models were used to estimate the association. The sensitivity analyses were conducted to estimate the effects of 1-month, 6-month and 1-year mean levels of exposure to black carbon on sleep quality. ResultsA total of 20,053 incoming college students were included. 29.3% reported impaired sleep quality, with a mean PSQI score of 4.3 ± 2.2. The logistic regression showed that the risk of impaired sleep quality was positively associated with black carbon exposure, especially in the highest quantile (OR: 1.26, 95% CI: 1.11–1.43) compared with the lowest quartile after adjusting for potential confounders. Subgroup analysis showed that the effect of black carbon on sleep quality was stronger in participants with higher BMI, lower household income, and lower parental educational level. The results of sensitivity analyses were similar with main analyses. ConclusionLong-term exposure to black carbon is associated with sleep disturbance in college students. Improvement of air quality may help improve sleep quality.

Personal and household PM2.5 and black carbon exposure measures and respiratory symptoms in 8 low- and middle-income countries

BackgroundHousehold air pollution (HAP) from cooking with solid fuels has been associated with adverse respiratory effects, but most studies use surveys of fuel use to define HAP exposure, rather than on actual air pollution exposure measurements. ObjectiveTo examine associations between household and personal fine particulate matter (PM2.5) and black carbon (BC) measures and respiratory symptoms. MethodsAs part of the Prospective Urban and Rural Epidemiology Air Pollution study, we analyzed 48-h household and personal PM2.5 and BC measurements for 870 individuals using different cooking fuels from 62 communities in 8 countries (Bangladesh, Chile, China, Colombia, India, Pakistan, Tanzania, and Zimbabwe). Self-reported respiratory symptoms were collected after monitoring. Associations between PM2.5 and BC exposures and respiratory symptoms were examined using logistic regression models, controlling for individual, household, and community covariates. ResultsThe median (interquartile range) of household and personal PM2.5 was 73.5 (119.1) and 65.3 (91.5) μg/m3, and for household and personal BC was 3.4 (8.3) and 2.5 (4.9) x10−5 m−1, respectively. We observed associations between household PM2.5 and wheeze (OR: 1.25; 95%CI: 1.07, 1.46), cough (OR: 1.22; 95%CI: 1.06, 1.39), and sputum (OR: 1.26; 95%CI: 1.10, 1.44), as well as exposure to household BC and wheeze (OR: 1.20; 95%CI: 1.03, 1.39) and sputum (OR: 1.20; 95%CI: 1.05, 1.36), per IQR increase. We observed associations between personal PM2.5 and wheeze (OR: 1.23; 95%CI: 1.00, 1.50) and sputum (OR: 1.19; 95%CI: 1.00, 1.41). For household PM2.5 and BC, associations were generally stronger for females compared to males. Models using an indicator variable of solid versus clean fuels resulted in larger OR estimates with less precision. ConclusionsWe used measurements of household and personal air pollution for individuals using different cooking fuels and documented strong associations with respiratory symptoms.

Non-linear models for black carbon exposure modelling using air pollution datasets

Black carbon (BC) is a product of incomplete combustion, present in urban aerosols and sourcing mainly from road traffic. Epidemiological evidence reports positive associations between BC and cardiovascular and respiratory disease. Despite this, BC is currently not regulated by the EU Air Quality Directive, and as a result BC data are not available in urban areas from reference air quality monitoring networks in many countries. To fill this gap, a machine learning approach is proposed to develop a BC proxy using air pollution datasets as an input. The proposed BC proxy is based on two machine learning models, support vector regression (SVR) and random forest (RF), using observations of particle mass and number concentrations (N), gaseous pollutants and meteorological variables as the input. Experimental data were collected from a reference station in Barcelona (Spain) over a 2-year period (2018–2019). Two months of additional data were available from a second urban site in Barcelona, for model validation. BC concentrations estimated by SVR showed a high degree of correlation with the measured BC concentrations (R2 = 0.828) with a relatively low error (RMSE = 0.48 μg/m3). Model performance was dependent on seasonality and time of the day, due to the influence of new particle formation events. When validated at the second station, performance indicators decreased (R2 = 0.633; RMSE = 1.19 μg/m3) due to the lack of N data and PM2.5 and the smaller size of the dataset (2 months). New particle formation events critically impacted model performance, suggesting that its application would be optimal in environments where traffic is the main source of ultrafine particles. Due to its flexibility, it is concluded that the model can act as a BC proxy, even based on EU-regulatory air quality parameters only, to complement experimental measurements for exposure assessment in urban areas.

Ceramide metabolism mediates the impaired glucose homeostasis following short-term black carbon exposure: A targeted lipidomic analysis

BackgroundAmbient particulate matter (PM), especially its carbonaceous composition black carbon (BC) increases cardiometabolic risks, yet the underlying mechanisms are incompletely understood. Ceramides (Cer; a class of sphingolipids) are biological intermediates in glucose metabolism. ObjectivesTo explore whether Cer metabolism mediates impaired glucose homeostasis following short-term PM exposure. MethodsIn a panel study in Beijing, China, 112 participants were followed-up between 2016 and 2017. Targeted lipidomic analyses quantified 26 sphingolipids in 387 plasma samples. Ambient BC and PM with aerodynamic diameter ≤ 2.5 μm (PM2.5) were continuously monitored in a station. We examined the associations of sphingolipid levels with average BC and PM2.5 concentrations 1–14 days before clinical visits using linear mixed-effects models, and explored the mediation effects of sphingolipids on PM-associated fasting blood glucose (FBG) difference using mediation analyses. ResultsIncreased levels of FBG and multiple sphingolipids in Cer metabolic pathways were associated with BC exposure in 1–14-day time window, but not with PM2.5 exposure. For each 10 μg/m3 increase in the average BC concentration 1–14 days before the clinical visits, species in the Cer C24:1 pathway (Cer, dihydroceramide, hexosylceramide, lactosylceramide, and sphingomyelin C24:1) increased in levels ranging from 11.8% (95% confidence interval [CI]: −6.2–33.2) to 48.7% (95% CI: 8.8–103.4), as did the Cer C16:0, C18:0, and C20:0 metabolic pathway species, ranging from 3.2% (95% CI: −5.6–12.9) to 32.4% (95% CI: 7.0–63.8), respectively. The Cer C24:1 metabolic pathway species mediated 6.5–25.5% of the FBG increase associated with BC exposure in 9-day time window. The Cer C16:0, C18:0, and C20:0 metabolic pathway species mediated 5.4–26.2% of the BC-associated FBG difference. Conclusions: In conclusion, Cer metabolism may mediate impaired glucose homeostasis following short-term BC exposure. The current findings are preliminary, which need to be corroborated by further studies.

Effect of NLRP3 repression on NLRP3 inflammasome activation in human corneal epithelial cells with black carbon exposure

Purpose To investigate the inhibitory effects of NLRP3 siRNA on NLRP3 inflammasome activation in human corneal epithelial cells (HCECs) with fresh black carbon (FBC) particles and ozone-oxidized BC (OBC) particles treatment. Methods HCECs were transfected with NLRP3 siRNA or control siRNA for 48 h, followed by 200 μg/ml FBC or OBC suspension for an additional 72 h. Untreated controls were cells with no siRNA transfection or BC treatment. RT-qPCR and Western blot were used to measure mRNA and protein levels of components of the NLRP3 inflammasome (NLRP3, ASC, and Caspase-1) and downstream cytokine (IL-1β), respectively. Results Compared with untreated control cells, mRNA levels of NLRP3, ASC, Caspase-1, and IL-1β were significantly higher (p < 0.05) in control siRNA transfected cells with BC treatments. Compared with the control siRNA transfected cells, NLRP3 siRNA transfection reduced the expression of NLRP3 and ASC, whereas it had a limited effect on the expression of Caspase-1 and IL-1β with FBC or OBC exposures. Under FBC treatment, the reductions of NLRP3 and Caspase-1 mRNA levels were 53.5% (p < 0.001) and 34.2% (p < 0. 01), respectively, and NLRP3 and ASC protein levels were lowered by 58.2% (p < 0.001) and 45.4% (p < 0.001), respectively. Under OBC treatment, the reductions of NLRP3 and Caspase-1 mRNA levels were 39.8% (p < 0.001) and 25.6% (p < 0.05), respectively, and NLRP3 and ASC protein levels were lowered by 44.8% (p < 0.001) and 41.7% (p < 0.001), respectively. Moreover, mRNA levels of ASC and IL-1β, the protein levels of Caspase-1 and IL-1β showed a tendency to decrease in NLRP3 siRNA transfected cells, it was statistically insignificant (p > 0.05). Conclusions NLRP3 siRNA transfection could partially reverse the increased mRNA levels of NLRP3 and Caspase-1, the protein levels of NLRP3 and ASC in HCECs with BC treatment, whereas the reductions of protein levels of Caspase-1 and IL-1β were not significant, indicating that NLRP3 siRNA has a limited inhibitory effect on the activation of NLRP3 inflammasome triggered by BC.

Assessment of black carbon exposure level and health economic loss in China.

Based on the geographic information system (GIS) software and the application of the black carbon (BC) and fine particulate matter ([Formula: see text]) ratio method, this paper analyzed and calculated the national BC distribution from 2015 to 2017 and evaluated the national human exposure to BC. The results showed that from 2015 to 2017, 2/3 of the national land area and nearly half of the population were exposed to 1-3 [Formula: see text], and the area and population exposed to a concentration less than 2 [Formula: see text] increased yearly, while the area and population exposed to a concentration higher than 9 [Formula: see text] decreased yearly. The estimated economic loss showed that 77.3% of the targeted districts or counties claimed a loss per square kilometer of 50 million Chinese Yuan (CNY) or less from the perspective of annual changes, and districts and counties in Beijing-Tianjin-Hebei and Hunan with annual losses between 50 and 500 million CNY showed an increasing trend. The BC ratio (the proportion of BC economic loss to GDP) of Beijing-Tianjin-Hebei and Hunan also showed an increasing trend yearly.

Air pollution in association with mental and self-rated health and the mediating effect of physical activity

BackgroundRecent studies showed that air pollution might play a role in the etiology of mental disorders. In this study we evaluated the association between air pollution and mental and self-rated health and the possible mediating effect of physical activity in this association.MethodsIn 2008, 2013 and 2018 the Belgian Health Interview Survey (BHIS) enrolled 16,455 participants who completed following mental health dimensions: psychological distress, suboptimal vitality, suicidal ideation, and depressive and generalized anxiety disorder and self-rated health. Annual exposure to nitrogen dioxide (NO2), particulate matter ≤ 2.5 µm (PM2.5) and black carbon (BC) were estimated at the participants’ residence by a high resolution spatiotemporal model. Multivariate logistic regressions were carried out taking into account a priori selected covariates.ResultsLong-term exposure to PM2.5, BC and NO2 averaged 14.5, 1.4, and 21.8 µg/m3, respectively. An interquartile range (IQR) increment in PM2.5 exposure was associated with higher odds of suboptimal vitality (OR = 1.27; 95% CI: 1.13, 1.42), poor self-rated health (OR = 1.20; 95% CI: 1.09, 1.32) and depressive disorder (OR = 1.19; 95% CI: 1.00, 1.41). Secondly, an association was found between BC exposure and higher odds of poor self-rated health and depressive and generalized anxiety disorder and between NO2 exposure and higher odds of psychological distress, suboptimal vitality and poor self-rated health. No association was found between long-term ambient air pollution and suicidal ideation or severe psychological distress. The mediation analysis suggested that between 15.2% (PM2.5-generalized anxiety disorder) and 40.1% (NO2-poor self-rated health) of the association may be mediated by a difference in physical activity.ConclusionsLong-term exposure to PM2.5, BC or NO2 was adversely associated with multiple mental health dimensions and self-rated health and part of the association was mediated by physical activity. Our results suggest that policies aiming to reduce air pollution levels could also reduce the burden of mental health disorders in Belgium.

Maternal exposure to black carbon and nitrogen dioxide during pregnancy and birth weight: Using machine-learning methods to achieve balance in inverse-probability weights

BackgroundLow birth weight is associated with increased risks of health problems in infancy and later life. Among the epidemiological analyses suggesting an association between air pollution and birth weight, few have estimated the effects of black carbon (BC) or together with nitrogen dioxide (NO2), and even fewer studies have used causal modelling. MethodsWe examined 1,119,011 birth records between 2001/01/01 and 2015/12/31 from the Massachusetts Birth Registry to investigate causal associations between prenatal exposure to BC and NO2 and birth weight. We calculated mean residential BC and NO2 exposures 0–30, and 31–280 days prior to birth from validated spatial-temporal models. We fit generalized propensity score models with gradient boosting tuned by a new algorithm to achieve covariate balance, then fit marginal structural models with stabilized inverse-probability weights. ResultsThroughout pregnancy, the average birth weight would drop by 17.0 g (95% CI: 15.4, 18.6) for an IQR increase of 0.14 μg/m3 in BC and would independently drop by 19.9 g (95% CI: 18.6, 21.3) for an IQR increase of 9.8 ppb in NO2. Most of the negative effects of BC on birth weight are from 0 to 30 days before the delivery date. The estimated odds ratio of low birth weight for every IQR increase during the entire pregnancy was 1.131 (95% CI: 1.106, 1.156) for BC and 1.082 (95% CI: 1.062, 1.103) for NO2. ConclusionsWe found that prenatal exposures to both BC and NO2 were associated with lower birth weight.

Daily personal exposure to black carbon in different microenvironments in Hanoi, Vietnam

Daily personal exposure to black carbon (BC) in different microenvironments in Hanoi, Vietnam was quantified for the first time. In this study, a portable instrument, microAethe® model AE51, was used to continuously measure BC concentrations in various microenvironments within buildings and transportation modes. Overall average daily personal exposure to BC from those microenvironments was 5.46 µg/h. The highest BC exposure was during commuting 13.48 µg/h and 5.74 µg/h for the motorcyclist and car driver, respectively. In building environments, the highest BC exposure was 3.98 µg/h in a coffee shop with smoking; the lowest BC exposure was 1.54 µg/h in a hospital department; while BC exposure in an office was 1.92 µg/h. The level of BC exposure in an apartment was strongly influenced by building ventilation modes. They were 3.58 µg/h and 2.15 µg/h with doors/windows open and closed, respectively. Our finding confirmed that commuting contributes disproportionately to the total BC exposure due to the high level of BC during traffic/travel. Building ventilation and air conditioning can significantly affect indoor BC levels and should be considered as a measure to reduce BC exposure within buildings in Hanoi.

Association of household air pollution with cellular and humoral immune responses among women in rural Bangladesh

Household air pollution (HAP) arising from combustion of biomass fuel (BMF) is a leading cause of morbidity and mortality in low-income countries. Air pollution may stimulate pro-inflammatory responses by activating diverse immune cells and cyto/chemokine expression, thereby contributing to diseases. We aimed to study cellular immune responses among women chronically exposed to HAP through use of BMF for domestic cooking. Among 200 healthy, non-smoking women in rural Bangladesh, we assessed exposure to HAP by measuring particulate matter 2.5 (PM2.5), black carbon (BC) and carbon monoxide (CO), through use of personal monitors RTI MicroPEM™ and Lascar CO logger respectively, for 48 h. Blood samples were collected following HAP exposure assessment and were analyzed for immunoprofiling by flow cytometry, plasma IgE by immunoassay analyzer and cyto/chemokine response from monocyte-derived-macrophages (MDM) and -dendritic cells (MDDC) by multiplex immunoassay. In multivariate linear regression model, a doubling of PM2.5 was associated with small increments in immature/early B cells (CD19+CD38+) and plasmablasts (CD19+CD38+CD27+). In contrast, a doubling of CO was associated with 1.20% reduction in CD19+ B lymphocytes (95% confidence interval (CI) = -2.36, −0.01). A doubling of PM2.5 and BC each was associated with 3.12% (95%CI = −5.85, −0.38) and 4.07% (95%CI = −7.96, −0.17) decrements in memory B cells (CD19+CD27+), respectively. Exposure to CO was associated with increased plasma IgE levels (beta(β) = 240.4, 95%CI = 3.06, 477.8). PM2.5 and CO exposure was associated with increased MDM production of CXCL10 (β = 12287, 95%CI = 1038, 23536) and CCL5 (β = 835.7, 95%CI = 95.5, 1576), respectively. Conversely, BC exposure was associated with reduction in MDDC-produced CCL5 (β = −3583, 95%CI = −6358, −807.8) and TNF-α (β = −15521, 95%CI = −28968, −2074). Our findings suggest that chronic HAP exposure through BMF use adversely affects proportions of B lymphocytes, particularly memory B cells, plasma IgE levels and functions of antigen presenting cells in rural women.

Association between personal exposure to household air pollution and gestational blood pressure among women using solid cooking fuels in rural Tamil Nadu, India

BackgroundThe Household Air Pollution Intervention Network (HAPIN) trial is an ongoing multi-center randomized controlled trial assessing the impact of a liquified petroleum gas (LPG) cookstove and fuel intervention on health. Given the potential impacts of household air pollution (HAP) exposure from burning solid fuels on cardiovascular health during pregnancy, we sought to determine whether baseline exposures to particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5), black carbon (BC) and carbon monoxide (CO) were associated with blood pressure among 799 pregnant women in Tamil Nadu, India, one of the HAPIN trial centers. MethodsMultivariable linear regression models were used to examine the association between 24-h personal exposure to PM2.5/BC/CO and systolic and diastolic blood pressure, controlling for maternal age, body mass index (BMI), mother's education, household wealth, gestational age, and season. At the time of measurement, women were between 9- and 20-weeks of gestation. ResultsWe found that systolic blood pressure (SBP) and diastolic blood pressure (DBP) were higher in pregnant women exposed to higher levels of HAP, though only the result for CO and DBP reached conventional statistical significance (p < 0.05). We observed a positive association between CO and DBP among the entire study cohort: a 1-log μg/m3 increase in CO exposure was associated with 0.36 mmHg higher DBP (95% confidence interval [CI]: 0.02 to 0.70). The effect was stronger in pregnant women with higher CO exposures (in the 3rd [≥ 0.9 and < 2.1 ppm] and 4th quartiles [≥ 2.1 and ≤ 46.9 ppm]). We also found that pregnant women with PM2.5 exposures in the highest quartile (≥ 129.9 and ≤ 2100 μg/m3) had a borderline significant association (p = 0.054) with DBP compared to those who had PM2.5 exposures in the lowest quartile (≥ 9.4 and < 47.7 μg/m3). No evidence of association was observed for BC exposure and blood pressure. ConclusionThis study contributes to limited evidence regarding the relationship between HAP exposure and blood pressure among women during pregnancy, a critical window for both mother and child's life-course health. Results from this cross-sectional study suggest that exposures to PM2.5 and CO from solid fuel use are associated with higher blood pressure in pregnant women during their first or second trimester.