Biomass fuel use and the exposure of children to particulate air pollution in southern Nepal

Association between usage of household cooking fuel and congenital birth defects-18 months multi-centric cohort study in Nepal

BACKGROUND

- An estimated 240,000 newborns die worldwide within 28 days of birth every year due to congenital birth defect. Exposure to poor indoor environment contributes to poor health outcomes. In this research, we aim to evaluate the association between the usage of different type household cooking fuel and congenital birth defects in Nepal, as well as investigate whether air ventilation usage had a modifying effect on the possible association.

METHODS

- This is a secondary analysis of multi-centric prospective cohort study evaluating Quality Improvement Project in 12 public referral hospitals of Nepal from 2017 to 2018. The study sample was 66,713 women with a newborn, whose information was available in hospital records and exit interviews. The association between cooking fuel type usage and congenital birth defects was investigated with adjusted multivariable logistic regression. To investigate the air ventilation usage, a stratified multivariable logistic regression analysis was performed.

RESULTS

-In the study population (N = 66,713), 60.0% used polluting fuels for cooking and 89.6% did not have proper air ventilation. The prevalence rate of congenital birth defect was higher among the families who used polluting fuels for cooking than those who used cleaner fuels (5.5/1000 vs. 3.5/1000, p < 0.001). Families using polluting fuels had higher odds (aOR 1.49; 95% CI; 1.16, 1.91) of having a child with a congenital birth defect compared to mothers using cleaner fuels adjusted with all available co-variates. Families not using ventilation while cooking had even higher but statistically insignificant odds of having a child with congenital birth defects (aOR 1.34; 95% CI; 0.86, 2.07) adjusted with all other variates.

CONCLUSION

- The usage of polluted fuels for cooking has an increased odds of congenital birth defects with no significant association with ventilation. This study adds to the increasing knowledge on the adverse effect of polluting fuels for cooking and the need for action to reduce this exposure.

Burden and risk factors of chronic respiratory diseases in Nepal, 1990-2019: An analysis of the global burden of diseases study

Background and Aims

Chronic respiratory diseases (CRDs) substantially contribute to morbidity and mortality globally and in Nepal. However, there is a paucity of evidence on the trend and the burden of CRDs in Nepal. This study reports the trend of the burden and contribution of major risk factors to CRDs in Nepal from 1990 to 2019.

Methods

This study is an observational study using publicly available data from Global Burden of Disease 2019 estimations for Nepal. The age-standardized and age-specific prevalence, incidence, mortality, disability-adjusted life years (DALYs), and risk factors for CRDs in Nepal were extracted to measure the burden and its trend. The data are presented as percentages or as rates per 100,000 population.

Results

The age-standardized incidence rate of CRDs in Nepal in 2019 was 913.6 per 100,000 (95% uncertainty interval [UI]: 828.7-1000.1), which was an increase of 7.7% from 848.6 per 100,000 (95% UI: 780.2-918.2) in 1990. However, the age-standardized prevalence rate [4453/100,000 (4234.2-4671.8) in 1990; 4457.1/100,000 (4255.2-4666.8) in 2019] was almost stagnant. Most CRDs attributed to deaths and DALYs were due to chronic obstructive pulmonary disease.

Conclusions

Air pollution and smoking are the main risk factors for DALYs due to CRDs in Nepal. This surging burden of the incidence rate of CRDs in Nepal calls for more effective actions to curb the risk factors and diseases.

Biomass fuel use for cooking in Nepalese families and child cognitive abilities, results from a community-based study

BACKGROUND

Biomass fuel use for cooking is widespread in low to middle income countries. Studies on the association between biomass fuel use and cognitive abilities in children are limited.

OBJECTIVE

To examine the association between biomass fuel use for cooking and cognitive abilities in Nepalese children at 4 years of age.

METHODS

In a cohort design we have information on biomass fuel use in the households of 533 children in infancy and cognitive abilities when they were 4 years old from a community-based sample. Cognitive abilities were measured by the Wechsler Preschool and Primary Scale of Intelligence, 4th edition (WPPSI-IV) and the NEPSY-II. We examined the associations between biomass fuel use and scores on the WPPSI-IV Full-Scale IQ (FSIQ) (primary outcome), and WPPSI index and NEPSY-II subtest scores in multiple linear regression models. The associations were also examined in predefined subgroups.

RESULTS

Ninety-nine (18.6%) of the families used biomass fuel for cooking. Children in these families had lower mean FSIQ than children in families with no biomass use (83.3 (95%CI 81.7, 85.0) vs. 85.3 (95%CI 84.5, 86.0)), with a mean difference of -2.2 (95%CI -3.9, -0.5) adjusting for demographics and socio-economic status. The association between biomass fuel use and cognitive abilities was strongest in subgroups of children from households with more than three rooms, with separate kitchen and bedroom, and with higher wealth-score. These interactions were significant for number of rooms in the home (p = 0.04), if the household had separate bedroom and kitchen (p = 0.05), and for the wealth-score (p = 0.03).

CONCLUSION

Biomass fuel use for cooking in Nepalese families was associated with lower overall cognitive abilities at 4 years. Uncertainties include exposure misclassification and unmeasured confounding. The associations between biomass fuel use and neurodevelopment in children needs further investigation with more precise measurements of the exposure.

A systematic literature review on indoor PM2.5 concentrations and personal exposure in urban residential buildings

Particulate matter with an aerodynamic diameter less than 2.5μm (PM_2.5) is currently a major air pollutant that has been raising public attention. Studies have found that short/long-term exposure to PM_2.5 lead detrimental health effects. Since people in most region of the world spend a large proportion of time in dwellings, personal exposure to PM_2.5 in home microenvironment should be carefully investigated. The objective of this review is to investigate and summary studies in terms of personal exposure to indoor PM_2.5 pollutants from the literature between 2000 and 2021. Factors from both outdoor and indoor environment that have impact on indoor PM_2.5 levels were explicated. Exposure studies were verified relating to individual activity pattern and exposure models. It was found that abundant investigations in terms of personal exposure to indoor PM_2.5 is affected by factors including concentration level, exposure duration and personal diversity. Personal exposure models, including microenvironment model, mathematical model, stochastic model and other simulation models of particle deposition in different regions of human airway are reviewed. Further studies joining indoor measurement and simulation of PM_2.5 concentration and estimation of deposition in human respiratory tract are necessary for individual health protection.

The association between biomass fuel use for cooking and linear growth in young children in Bhaktapur, Nepal

BACKGROUND

There are still many people in the world who prepare their meals on open fires or stoves using solid fuels from biomass, especially in low-and middle-income countries. Although biomass cooking fuels have been associated with adverse health impacts and diseases, the association with child linear growth remains unclear.

OBJECTIVES

In a cohort design, we aimed to describe the association between the use of biomass cooking fuels and linear growth in children aged 18-23 months living in the urban and peri-urban community of Bhaktapur, situated in the Kathmandu valley in Nepal.

METHODS

Caretakers of 600 marginally stunted children aged 6-11 months were interviewed about their source of cooking fuel and other socio-demographic characteristics at enrolment into a randomized controlled trial. Children's body length was measured when children were 18-23 months old. In linear regression models, we estimated the association between the use of biomass fuel and length-for-age Z-scores (LAZ), adjusted for relevant confounders. We repeated these analyses in pre-defined sub-groups and different percentiles of LAZ using quantile regression models.

RESULTS

Among study participants, 101 (18%) used biomass as cooking fuel. The association between biomass fuel and LAZ was not statistically significant in the full sample (adjusted regression coefficient: -0.14, 95% CI: -0.28, 0.00). The association was stronger in some of the sub-groups and in the lower tail of the LAZ distribution (those who are stunted), but neither reached statistical significance.

DISCUSSION

Children from households in poor, urban neighborhoods in Nepal which used biomass fuel for cooking were on average slightly shorter than other children, although the association only approached statistical significance. As this was an observational study, residual confounding cannot be excluded. Further studies are needed to confirm these associations, in particular those seen in certain sub-groups.

Comprehensive analysis of the association of seasonal variability with maternal and neonatal nutrition in lowland Nepal

OBJECTIVE

To provide a comprehensive seasonal analysis of pregnant mothers' eating behaviour and maternal/newborn nutritional status in an undernourished population from lowland rural Nepal, where weather patterns, agricultural labour, food availability and disease prevalence vary seasonally.

DESIGN

Secondary analysis of cluster-randomised Low Birth Weight South Asia Trial data, applying cosinor analysis to predict seasonal patterns.

OUTCOMES

Maternal mid-upper arm circumference (MUAC), BMI, dietary diversity, meals per day, eating down and food aversion in pregnancy (≥31 weeks' gestation) and neonatal z-scores of length-for-age (LAZ), weight-for-age (WAZ) and head circumference-for-age (HCAZ) and weight-for-length (WLZ).

SETTING

Rural areas of Dhanusha and Mahottari districts in plains of Nepal.

PARTICIPANTS

2831 mothers aged 13-50 and 3330 neonates.

RESULTS

We found seasonal patterns in newborn anthropometry and pregnant mothers' anthropometry, meal frequency, dietary diversity, food aversion and eating down. Seasonality in intake varied by food group. Offspring anthropometry broadly tracked mothers'. Annual amplitudes in mothers' MUAC and BMI were 0·27 kg/m2 and 0·22 cm, with peaks post-harvest and nadirs in October when food insecurity peaked. Annual LAZ, WAZ and WLZ amplitudes were 0·125, 0·159 and 0·411 z-scores, respectively. Neonates were the shortest but least thin (higher WLZ) in winter (December/January). In the hot season, WLZ was the lowest (May/June) while LAZ was the highest (March and August). HCAZ did not vary significantly. Food aversion and eating down peaked pre-monsoon (April/May).

CONCLUSIONS

Our analyses revealed complex seasonal patterns in maternal nutrition and neonatal size. Seasonality should be accounted for when designing and evaluating public heath nutrition interventions.

The use of bluetooth low energy Beacon systems to estimate indirect personal exposure to household air pollution

Household air pollution (HAP) generated from solid fuel combustion is a major health risk. Direct measurement of exposure to HAP is burdensome and challenging, particularly for children. In a pilot study of the Household Air Pollution Intervention Network (HAPIN) trial in rural Guatemala, we evaluated an indirect exposure assessment method that employs fixed continuous PM2.5 monitors, Bluetooth signal receivers in multiple microenvironments (kitchen, sleeping area and outdoor patio), and a wearable signal emitter to track an individual's time within those microenvironments. Over a four-month period, we measured microenvironmental locations and reconstructed indirect PM2.5 exposures for women and children during two 24-h periods before and two periods after a liquefied petroleum gas (LPG) stove and fuel intervention delivered to 20 households cooking with woodstoves. Women wore personal PM2.5 monitors to compare direct with indirect exposure measurements. Indirect exposure measurements had high correlation with direct measurements (n = 62, Spearman ρ = 0.83, PM2.5 concentration range: 5-528 µg/m3). Indirect exposure had better agreement with direct exposure measurements (bias: -17 µg/m3) than did kitchen area measurements (bias: -89 µg/m3). Our findings demonstrate that indirect exposure reconstruction is a feasible approach to estimate personal exposure when direct assessment is not possible.

Geographic and socio-economic variation in markers of indoor air pollution in Nepal: evidence from nationally-representative data

Background

In low-income countries such as Nepal, indoor air pollution (IAP), generated by the indoor burning of biomass fuels, is the top-fourth risk factor driving overall morbidity and mortality. We present the first assessment of geographic and socio-economic determinants of the markers of IAP (specifically fuel types, cooking practices, and indoor smoking) in a nationally-representative sample of Nepalese households.

Methods

Household level data on 11,040 households, obtained from the 2016 Nepal Demographic and Health Survey, were analyzed. Binary logistic regression analyses were conducted to assess the use of fuel types, indoor cooking practices, indoor smoking and IAP with respect to socio-economic indicators and geographic location of the household.

Results

More than 80% of the households had at least one marker of IAP: 66% of the household used unclean fuel, 45% did not have a separate kitchen to cook in, and 43% had indoor smoking. In adjusted binary logistic regression, female and educational attainment of household’s head favored cleaner indoor environment, i.e., using clean fuel, cooking in a separate kitchen, not smoking indoors, and subsequently no indoor pollution. In contrast, households belonging to lower wealth quintile and rural areas did not favor a cleaner indoor environment. Households in Province 2, compared to Province 1, were particularly prone to indoor pollution due to unclean fuel use, no separate kitchen to cook in, and smoking indoors. Most of the districts had a high burden of IAP and its markers.

Conclusions

Fuel choice and clean indoor practices are dependent on household socio-economic status. The geographical disparity in the distribution of markers of IAP calls for public health interventions targeting households that are poor and located in rural areas.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-6512-z) contains supplementary material, which is available to authorized users.

Characteristics of indoor air pollution and estimation of respiratory dosage under varied fuel-type and kitchen-type in the rural areas of Telangana state in India

Indoor Air Pollution (IAP) is one of the top environmental risks in developing countries including India, with more than a million deaths annually, predominantly through Particulate Matter (PM) exposure. The current study deals with the measurement of PM concentrations in rural households under varied fuel and kitchen-types, evaluation of the indoor air pollution (IAP) characteristics and estimation of respiratory dosage for the different subjects (women, young children and the elderly). Monitoring of particulate matter (PM) was carried out during summer, monsoon and winter season with biomass, LPG and combine of biomass and LPG being used as fuel for cooking. Furthermore, different types of indoor kitchens (with partition and without partition) and outdoor kitchens (separate enclose kitchen and open kitchen) were also considered as kitchen type along with fuel are two crucial factors contributing to IAP. Deposition fractions were calculated using Multiple Particle Path Dosimetry (MPPD) to study the deposition patterns in different parts of the human respiratory tract (HRT) - head, tracheobronchial and pulmonary for women, young children and the elderly people. Dosage of particulate matter was calculated by inputting the recorded PM measurements, a comparison made for biomass-LPG and dosage intensification due to the kitchen-type presented. While the biomass households exhibited high levels of dosage (1181.4 to 5891.7 μg) against the LPG households (89.9 to 811.2 μg), the indoor kitchen types exhibited a maximum intensification of 10.6 times than outdoor kitchens with the same fuel. This study not only establishes the IAP characteristics but also quantifies the role of fuel-type and kitchen-type in IAP. The study also indicates various measures that could be deployed to reduce dosage and thus minimize the health risks.

Potential Impacts of Modifiable Behavioral and Environmental Exposures on Reducing Burden of Under-five Mortality Associated with Household Air Pollution in Nepal

Objectives Household air pollution (HAP) is one of the leading causes of respiratory illness and deaths among young children in low and lower-middle income countries. This study examines for the first time trends in the association between HAP from cooking fuel and under-five mortality and measures the potential impact of interventions to reduce HAP using Nepal Demographic and Health Survey datasets (2001-2011). Methods A total of 17,780 living children across four age-groups (neonatal 0-28 days, post-neonatal 1-11 months, child 12-59 months and under-five 0-59 months) were included and multi-level logistic regression models were used for analyses. Population attributable fractions of key risk factors and potential impact fractions assessing the impact of previous interventions to reduce exposure prevalence were also calculated. Results Use of cooking fuel was associated with total under-five mortality (OR 2.19, 95% CI 1.37-3.51, P = 0.001) in Nepal, with stronger associations evident for sub-group analyses of neonatal mortality (OR 2.67, 95% CI 1.47-4.82, P = 0.001). Higher association was found in rural areas and for households without a separate kitchen using polluting fuel for cooking, and in women who had never breastfed for all age-groups of children. PIF estimates, assuming a 63% of reduction of HAP based on previously published interventions in Nepal, suggested that a burden of 40% of neonatal and 33% of under-five mortality cases associated with an indoor kitchen using polluting fuel could be avoidable. Conclusion Improved infrastructure and behavioral interventions could help reduce the pollution from cooking fuel in the household resulting in further reduction in under-five mortality in Nepal.

Approximation of personal exposure to fine particulate matters (PM2.5) during cooking using solid biomass fuels in the kitchens of rural West Bengal, India

More than 85% of the rural Indian households use traditional solid biofuels (SBFs) for daily cooking. Burning of the easily available unprocessed solid fuels in inefficient earthen cooking stoves produce large quantities of particulate matters. Smaller particulates, especially with aerodynamic diameter of 2.5 μm or less (PM_2.5), largely generated during cooking, are considered to be health damaging in nature. In the present study, kitchen level exposure of women cooks to fine particulate matters during lunch preparation was assessed considering kitchen openness as surrogate to the ventilation condition. Two-way ANCOVA analysis considering meal quantity as a covariate revealed no significant interaction between the openness and the seasons explaining the variability of the personal exposure to the fine particulate matters in rural kitchen during cooking. Multiple linear regression analysis revealed the openness as the only significant predictor for personal exposure to the fine particulate matters. In the present study, the annual average fine particulate matter exposure concentration was found to be 974 μg m^-3.

Prevalence and determinants of airflow limitation in urban and rural children exposed to cooking fuels in South-East Nigeria

Background Biofuels and other cooking fuels are used in households in low- and middle-income countries. Aim To investigate the impact of cooking fuels on lung function in children in urban and rural households in South-East Nigeria. Methods The multi-stage sampling method was used to enroll children exposed to cooking fuel in the communities. Lung function values FEV1, FVC and the FEV1/FVC ratio, were measured with ndd EasyOne^R spirometer. Airflow limitation was determined with FEV1/FVC Z-score values at -1.64 as the lower limit of normal (LLN5). The Global Lung Function Initiative 2012 software was used to calculate the lung function indices. Results The median age (range) of the 912 children enrolled was 10.6 years (6-18). Altogether, 468 (51.6%) children lived in rural areas. Seven hundred and thirty-seven (80.7%) were directly exposed to cooking fuels (418/737, 56.5% in rural areas). Wood and kerosene were the dominant fuels in rural and urban households. The respective mean Z-scores of the exposed children in rural and urban were zFEV1 -0.62, FVC -0.21, FEV1/FVC -0.83 and zFEV1 -0.57, zFVC -0.14, FEV1/FVC -0.75. Few (5.2%, 38/737) of the children had airflow limitation. Most of them (60.5%, 25/38) lived in the rural community; the lowest FEV1/FVC Z-scores were those of exposed to a combination of fuels. Conclusion Exposure to cooking fuels affects lung function in children with airway limitation in a small proportion, Control measures are advocated to reduce the morbidity related to cooking fuels exposure.

Women's Ideas about the Health Effects of Household Air Pollution, Developed through Focus Group Discussions and Artwork in Southern Nepal

Household air pollution is a major cause of ill health, but few solutions have been effective to date. While many quantitative studies have been conducted, few have explored the lived experiences and perceptions of women who do the cooking, and as a result are those most exposed to household air pollution. In this study, we worked with groups of home cooks, and sought to use art as a means of engaging them in discussions of how household air pollution from cooking affects their lives. In the Terai district of southern Nepal, we held four focus groups that included 26 local women from urban and peri-urban areas, as well as six local artists. The women then met approximately weekly over four months, and produced images related to air pollution. Transcripts from the focus groups were reviewed independently by two authors, who initially categorised data deductively to pre-defined nodes, and subsequently inductively reviewed emergent themes. Women identified a number of health effects from air pollution. The main physical effects related to the eye and the respiratory system, and women and young children were seen as most vulnerable. The psychosocial effects of air pollution included reduced food intake by women and lethargy. Suggested solutions included modifications to the cooking process, changing the location of stoves, and increasing ventilation. The main barriers were financial. The lived experiences of women in southern Nepal around the problem of air pollution offers a more nuanced and context-specific understanding of the perceptions and challenges of addressing air pollution, which can be used to inform future interventions.

Attributable risk and potential impact of interventions to reduce household air pollution associated with under-five mortality in South Asia

BACKGROUND

Solid fuel use is the major source of household air pollution (HAP) and accounts for a substantial burden of morbidity and mortality in low and middle income countries. To evaluate and compare childhood mortality attributable to HAP in four South Asian countries.

METHODS

A series of Demographic and Health Survey (DHS) datasets for Bangladesh, India, Nepal and Pakistan were used for analysis. Estimates of relative risk and exposure prevalence relating to use of cooking fuel and under-five mortality were used to calculate population attributable fractions (PAFs) for each country. Potential impact fractions (PIFs) were also calculated assessing theoretical scenarios based on published interventions aiming to reduce exposure prevalence.

RESULTS

There are an increased risk of under-five mortality in those exposed to cooking fuel compared to those not exposed in the four South Asian countries (OR = 1.30, 95% CI = 1.07-1.57, P = 0.007). Combined PAF estimates for South Asia found that 66% (95% CI: 43.1-81.5%) of the 13,290 estimated cases of under-five mortality was attributable to HAP. Joint PIF estimates (assuming achievable reductions in HAP reported in intervention studies conducted in South Asia) indicates 47% of neonatal and 43% of under-five mortality cases associated with HAP could be avoidable in the four South Asian countries studied.

CONCLUSIONS

Elimination of exposure to use of cooking fuel in the household targeting valuable intervention strategies (such as cooking in separate kitchen, improved cook stoves) could reduce substantially under-five mortality in South Asian countries.

Status of indoor air pollution (IAP) through particulate matter (PM) emissions and associated health concerns in South Asia

Exposure to particulate emissions poses a variety of public health concerns worldwide, specifically in developing countries. This review summarized the documented studies on indoor particulate matter (PM) emissions and their major health concerns in South Asia. Reviewed literature illustrated the alarming levels of indoor air pollution (IAP) in India, Pakistan, Nepal, and Bangladesh, while Sri Lanka and Bhutan are confronted with relatively lower levels, albeit not safe. To our knowledge, data on this issue are absent from Afghanistan and Maldives. We found that the reported levels of PM₁₀ and PM_2.5 in Nepal, Pakistan, Bangladesh, and India were 2-65, 3-30, 4-22, 2-28 and 1-139, 2-180, 3-77, 1-40 fold higher than WHO standards for indoor PM₁₀ (50 μg/m³) and PM_2.5 (25 μg/m³), respectively. Regarding IAP-mediated health concerns, mortality rates and incidences of respiratory and non-respiratory diseases were increasing with alarming rates, specifically in India, Pakistan, Nepal, and Bangladesh. The major cause might be the reliance of approximately 80% population on conventional biomass burning in the region. Current review also highlighted the prospects of IAP reduction strategies, which in future can help to improve the status of indoor air quality and public health in South Asia.

Impact of partial fuel switch on household air pollutants in sub-Sahara Africa

Over 700 million people in Sub-Saharan Africa depend on solid biomass fuel and use simple cookstoves in poorly ventilated kitchens, which results in high indoor concentrations of household air pollutants. Switching from biomass to biogas as a cooking fuel can reduce airborne emissions of fine particulate matter (PM_2.5) and carbon monoxide (CO), but households often only partially convert to biogas, continuing to use solid biomass fuels for part of their daily cooking needs. There is little evidence of the benefits of partial switching to biogas. This study monitored real-time PM_2.5 and CO concentrations in 35 households in Cameroon and Uganda where biogas and firewood (or charcoal) were used. The 24 h mean PM_2.5 concentrations in households that used: (1) firewood and charcoal; (2) both firewood (mean 54% cooking time) and biogas (mean 46% cooking time); and (3) only biogas, were 449 μg m^-3, 173 μg m^-3 and 18 μg m^-3 respectively. The corresponding 24 h mean CO concentrations were 14.2 ppm, 2.7 ppm and 0.5 ppm. Concentrations of both PM_2.5 and CO were high and exceeded the World Health Organisation guidelines when firewood and charcoal were used. Partially switching to biogas reduced CO exposure to below the World Health Organisation guidelines, but PM_2.5 concentrations were only below the 24 h recommended limits when households fully converted to biogas fuel. These results indicate that partial switching from solid fuels to biogas is not sufficient and continues to produce concentrations of household air pollution that are likely to harm the health of those exposed. Programmes introducing biogas should aim to ensure that household energy needs can be fully achieved using biogas with no requirement to continue using solid fuels.

Pilot Intervention Study of Household Ventilation and Fine Particulate Matter Concentrations in a Low-Income Urban Area, Dhaka, Bangladesh

Fine particulate matter (PM_2.5) is a risk factor for pneumonia; ventilation may be protective. We tested behavioral and structural ventilation interventions on indoor PM_2.5 in Dhaka, Bangladesh. We recruited 59 good ventilation (window or door in ≥ 3 walls) and 29 poor ventilation (no window, one door) homes. We monitored baseline indoor and outdoor PM_2.5 for 48 hours. We asked all participants to increase ventilation behavior, including opening windows and doors, and operating fans. Where permitted, we installed windows in nine poor ventilation homes, then repeated PM_2.5 monitoring. We estimated effects using linear mixed-effects models and conducted qualitative interviews regarding motivators and barriers to ventilation. Compared with poor ventilation homes, good ventilation homes were larger, their residents wealthier and less likely to use biomass fuel. In multivariable linear mixed-effects models, ventilation structures and opening a door or window were inversely associated with the number of hours PM_2.5 concentrations exceeded 100 and 250 μg/m³. Outdoor air pollution was positively associated with the number of hours PM_2.5 concentrations exceeded 100 and 250 μg/m³. Few homes accepted window installation, due to landlord refusal and fear of theft. Motivators for ventilation behavior included cooling of the home and sunlight; barriers included rain, outdoor odors or noise, theft risk, mosquito entry, and, for fan use, perceptions of wasting electricity or unavailability of electricity. We concluded that ventilation may reduce indoor PM_2.5 concentrations but, there are barriers to increasing ventilation and, in areas with high ambient PM_2.5 concentrations, indoor concentrations may remain above recommended levels.

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.

Household air pollution from various types of rural kitchens and its exposure assessment

Exposure to household air pollutants has become a leading environmental health risk in developing countries. Considering this, real-time temporal variation in fine particulate matter (PM_2.5) and carbon monoxide (CO) concentrations were measured in various types of rural household kitchens. Observed average concentrations of PM_2.5, CO, percent relative humidity (%RH) and temperature (T) in five different kitchen types were 549.6μg/m³, 4.2ppm, 70.2% and 20°C respectively. Highest CO and PM_2.5 concentration were found in household performing cooking in indoor kitchens (CO: 9.3ppm; PM_2.5: 696.5μg/m³) followed by outdoor kitchens (CO: 5.8ppm; PM_2.5: 539.5μg/m³). The concentration of PM_2.5 and CO varied according to the fuel type and highest concentration was observed in kitchens using cowdung cakes followed by agricultural residue>firewood>biogas>Liquefied Petroleum Gas (LPG). Results revealed that the pollutants concentration varied with kitchen type, fuel type and the location of kitchen. An exposure index was developed to calculate the exposure of cook, non-cook and children below 5years. Analysis of exposure index values shows that cooks, who use solid biomass fuel (SBF) in indoor kitchen, are four times more exposed to the harmful pollutants than the cooks using clean fuel. Further, using indoor PM_2.5 concentrations, hazard quotient was calculated based on evaluation of intake concentration and toxicological risk, which also shows that SBF users have higher health risks (hazard quotient>1) than the clean fuel (LPG) users.

Factors associated with infant mortality in Nepal: a comparative analysis of Nepal demographic and health surveys (NDHS) 2006 and 2011

Background

Infant mortality is one of the priority public health issues in developing countries like Nepal. The infant mortality rate (IMR) was 48 and 46 per 1000 live births for the year 2006 and 2011, respectively, a slight reduction during the 5 years’ period. A comprehensive analysis that has identified and compared key factors associated with infant mortality is limited in Nepal, and, therefore, this study aims to fill the gap.

Methods

Datasets from Nepal Demographic and Health Surveys (NDHS) 2006 and 2011 were used to identify and compare the major factors associated with infant mortality. Both surveys used multistage stratified cluster sampling techniques. A total of 8707 and 10,826 households were interviewed in 2006 and 2011, with more than 99% response rate in both studies. The survival information of singleton live-born infants born 5 years preceding the two surveys were extracted from the ‘childbirth’ dataset. Multiple logistic regression analysis using a hierarchical modelling approach with the backward elimination method was conducted. Complex Samples Analysis was used to adjust for unequal selection probability due to the multistage stratified cluster-sampling procedure used in both NDHS.

Results

Based on NDHS 2006, ecological region, succeeding birth interval, breastfeeding status and type of delivery assistance were found to be significant predictors of infant mortality. Infants born in hilly region (AOR = 0.43, p = 0.013) and with professional assistance (AOR = 0.27, p = 0.039) had a lower risk of mortality. On the other hand, infants with succeeding birth interval less than 24 months (AOR = 6.66, p = 0.001) and those who were never breastfed (AOR = 1.62, p = 0.044) had a higher risk of mortality.

Based on NDHS 2011, birth interval (preceding and succeeding) and baby’s size at birth were identified to be significantly associated with infant mortality. Infants born with preceding birth interval (AOR = 1.94, p = 0.022) or succeeding birth interval (AOR = 3.22, p = 0.002) shorter than 24 months had higher odds of mortality while those born with a very large or larger than average size had significantly lowered odds (AOR = 0.17, p = 0.008) of mortality.

Conclusion

IMR and associated risk factors differ between NDHS 2006 and 2011 except ‘succeeding birth interval’ which attained significant status in the both study periods. This study identified the ecological region, birth interval, delivery assistant type, baby’s birth size and breastfeeding status as significant predictors of infant mortality.

Patterns of domestic exposure to carbon monoxide and particulate matter in households using biomass fuel in Janakpur, Nepal

Household Air Pollution (HAP) from biomass cooking fuels is a major cause of morbidity and mortality in low-income settings worldwide. In Nepal the use of open stoves with solid biomass fuels is the primary method of domestic cooking. To assess patterns of domestic air pollution we performed continuous measurement of carbon monoxide (CO) and particulate Matter (PM2.5) in 12 biomass fuel households in Janakpur, Nepal. We measured kitchen PM2.5 and CO concentrations at one-minute intervals for an approximately 48-h period using the TSI DustTrak II 8530/SidePak AM510 (TSI Inc, St. Paul MN, USA) or EL-USB-CO data logger (Lascar Electronics, Erie PA, USA) respectively. We also obtained information regarding fuel, stove and kitchen characteristics and cooking activity patterns. Household cooking was performed in two daily sessions (median total duration 4 h) with diurnal variability in pollutant concentrations reflecting morning and evening cooking sessions and peak concentrations associated with fire-lighting. We observed a strong linear relationship between PM2.5 measurements obtained by co-located photometric and gravimetric monitoring devices, providing local calibration factors of 4.9 (DustTrak) and 2.7 (SidePak). Overall 48-h average CO and PM2.5 concentrations were 5.4 (SD 4.3) ppm (12 households) and 417.6 (SD 686.4) μg/m3 (8 households), respectively, with higher average concentrations associated with cooking and heating activities. Overall average PM2.5 concentrations and peak 1-h CO concentrations exceeded WHO Indoor Air Quality Guidelines. Average hourly PM2.5 and CO concentrations were moderately correlated (r = 0.52), suggesting that CO has limited utility as a proxy measure for PM2.5 exposure assessment in this setting. Domestic indoor air quality levels associated with biomass fuel combustion in this region exceed WHO Indoor Air Quality standards and are in the hazardous range for human health.

Children's personal exposure to air pollution in rural villages in Bhutan

Exposure assessment studies conducted in developing countries have been based on fixed-site monitoring to date. This is a major deficiency, leading to errors in estimating the actual exposures, which are a function of time spent and pollutant concentrations in different microenvironments. This study quantified school children's daily personal exposure to ultrafine particles (UFP) using real-time monitoring, as well as volatile organic compounds (VOCs) and NO2 using passive sampling in rural Bhutan in order to determine the factors driving the exposures. An activity diary was used to track children's time activity patterns, and difference in mean exposure levels across sex and indoor/outdoor were investigated with ANOVA. 82 children, attending three primary schools participated in this study; S1 and S2 during the wet season and S3 during the dry season. Mean daily UFP exposure (cm(-3)) was 1.08×10(4) for children attending S1, 9.81×10(3) for S2, and 4.19×10(4) for S3. The mean daily NO2 exposure (µg m(-3)) was 4.27 for S1, 3.33 for S2 and 5.38 for S3 children. Likewise, children attending S3 also experienced higher daily exposure to a majority of the VOCs than those attending S1 and S2. Time-series of UFP personal exposures provided detailed information on identifying sources of these particles and quantifying their contributions to the total daily exposures for each microenvironment. The highest UFP exposure resulted from cooking/eating, contributing to 64% of the daily exposure, due to firewood combustion in houses using traditional mud cookstoves. The lowest UFP exposures were during the hours that children spent outdoors at school. The outcomes of this study highlight the significant contributions of lifestyle and socio-economic factors in personal exposures and have applications in environmental risk assessment and household air pollution mitigation in Bhutan.

Real-time particulate and CO concentrations from cookstoves in rural households in Udaipur, India

Almost 3 billion people around the globe use traditional three-stone cookstoves and open fires to warm and feed themselves. The World Health Organization estimates annual mortality rates from domestic solid fuel combustion to be around 4 million. One of the most affected countries is India. Quantifying pollutant concentrations from these cookstoves during different phases of operation and understanding the factors influencing their variability may help to identify where improvements should be targeted, enhancing indoor air quality for millions of the world's most vulnerable people. Gas and particulate measurements were collected between June and August, 2012, for 51 households using traditional cookstoves, in the villages of Udaipur district, Rajasthan, India. Mean pollutant concentrations during steady-state mode were 4989 μm(2) cm(-3), 9835 μg m(-3), and 18.5 ppm for lung-deposited surface area, PM2.5, and CO, respectively. Simple and multivariate regression analysis was conducted. Fuel amount, fuel diameter, duration of the cookstove run, roof-type, and the room dimension explained between 7% and 21% of the variability for the pollutant metrics. CO demonstrated weaker correlations with explanatory variables. Some of these variables may be indicative of socio-economic status and could be used as proxies of exposure in lieu of pollutant measurements, hence these variables may help identify which households to prioritize for intervention. Such associations should be further explored.

Effects of antenatal multiple micronutrient supplementation on lung function in mid-childhood: follow-up of a double-blind randomised controlled trial in Nepal

A randomised trial of prenatal multiple micronutrient supplementation in Nepalese women increased birthweight and weight at 2 years of age in offspring, compared to those born to mothers who only received iron and folic acid supplements. Further follow-up of this cohort provided an opportunity to investigate the effect of antenatal multiple micronutrients on subsequent lung function by measuring spirometry at 7-9 years of age in C: hildren born during the trial. 841 children (80% of the cohort) were seen at mean±sd 8.5±0.4 years. Technically successful spirometry results were obtained in 793 (94.3%) children, 50% of whom had been randomised to micronutrient supplementation. Background characteristics, including anthropometry, were similar in the two allocation groups. Lung function was also similar, mean (95% CI) difference in z-scores (supplementation minus control) was -0.08 (-0.19-0.04), -0.05 (-0.17-0.06) and -0.04 (-0.15-0.07) for forced expiratory volume in 1 s (FEV1), forced vital capacity and FEV1/FVC, respectively. Compared with healthy white children, FEV1 and FVC in the "healthy" Nepalese children were ∼1 (∼13%) z-score lower, with no difference in FEV1/FVC. We conclude that, compared with routine iron and folic acid, multiple micronutrient supplementation during pregnancy has no effect on spirometric lung function in Nepalese children at 8.5 years of age.

Household environment and behavioral determinants of respiratory tract infection in infants and young children in northern Bangladesh

OBJECTIVES

Respiratory tract infections (RTI) are one of the leading causes of under-five mortality in Bangladesh. Solid biomass fuels are the main source of domestic fuel used for cooking across Bangladesh, leading to smoke and pollution exposure in the home. This article aims to identify risk factors for RTI among children aged under five years in Bangladesh with a particular focus on the household environment, fuel use, and cooking practices.

METHODS

A cross-sectional household-health survey was carried out in 321 households in northern Bangladesh. The survey included care-giver interviews on cooking practices, child health, and household behaviors during cooking. Health status of the youngest child (under five years) from each household was recorded through maternal interviews, medical diagnosis, and assessment of biomarkers (C-reactive protein (CRP), hemoglobin) from finger-prick blood samples. Anthropometric status (weight, height) was recorded.

RESULTS

Children who spent ≥30 minutes/day within 5 feet of the stove during cooking had a significantly increased risk of moderate/severe RTI compared with children spending <30 minutes/day close to the stove (OR = 2.15, 95%CI: 1.20-3.86, P = 0.01), independent of socio-economic status (SES), biomass fuel type (wood, dung, plant-derived, compressed rice husks), child age, anthropometric status, CRP and hemoglobin.

CONCLUSIONS

In environments with a heavy reliance on solid biomass fuels, the amount of time a child spends near the stove during cooking may be an important risk for RTI. These novel findings from Bangladesh warrant further investigation of mother-infant behaviors during cooking in relation to child health, to ascertain whether the association is likely to be causal.

Cross-sectional study of asthma and rhinitis symptoms in the context of exposure to air pollution in Nepal

Asthma is common in children worldwide, although its prevalence varies substantially by location. The prevalence of wheeze over a 12-month period ranged from 2.1% to 32.2% in the older age group (13–14 years) and 4.1% to 32.1% in the younger age group (6–7 years) [1]. There is a positive association between current symptoms of asthma in younger and older children with gross national income [2], and it is generally slightly less common in girls than boys in the younger group [1–3]. Exposure to air pollution is associated with asthma exacerbations. Odds ratios for wheeze in the past year and the use of solely an open fire for cooking were 2.17 (95% CI 1.64–2.87) for children aged 6–7 years and 1.35 (95% CI 1.11–1.64) for children aged 13–14 years [4]. Nepalese children are exposed to high levels of indoor air pollution from the burning of biomass fuels [5]. This study aimed to estimate their prevalence of asthma, and to investigate the association of air pollution and risk of wheeze and rhinitis symptoms using personal exposure estimates of air pollution.

Amongst children in rural Nepal, an association of dry cough with air pollution was seen only in boyshttp://ow.ly/MOa5u

Sustained use of biogas fuel and blood pressure among women in rural Nepal

BACKGROUND

More than two fifths of the world's population cook with solid fuels and are exposed to household air pollution (HAP). As of now, no studies have assessed whether switching to alternative fuels like biogas could impact cardiovascular health among cooks previously exposed to solid fuel use.

METHODS

We conducted a propensity score matched cross-sectional study to explore if the sustained use of biogas fuel for at least ten years impacts blood pressure among adult female cooks of rural Nepal. We recruited one primary cook ≥ 30 years of age from each biogas (219 cooks) and firewood (300 cooks) using household and measured their systolic (SBP) and diastolic blood pressure (DBP). Household characteristics, kitchen ventilation and 24-h kitchen carbon monoxide were assessed. We matched cooks by age, body mass index and socio-economic status score using propensity scores and investigated the effect of biogas use through multivariate regression models in two age groups, 30-50 years and >50 years to account for any post-menopausal changes.

RESULTS

We found substantially reduced 24-h kitchen carbon monoxide levels among biogas-using households. After matching and adjustment for smoking, kitchen characteristics, ventilation status and additional fuel use, the use of biogas was associated with 9.8 mmHg lower SBP [95% confidence interval (CI), -20.4 to 0.8] and 6.5 mmHg lower DBP (95% CI, -12.2 to -0.8) compared to firewood users among women >50 years of age. In this age group, biogas use was also associated with 68% reduced odds [Odds ratio 0.32 (95% CI, 0.14 to 0.71)] of developing hypertension. These effects, however, were not identified in younger women aged 30-50 years.

CONCLUSIONS

Sustained use of biogas for cooking may protect against cardiovascular disease by lowering the risk of high blood pressure, especially DBP, among older female cooks. These findings need to be confirmed in longitudinal or experimental studies.

Effect of antenatal multiple micronutrient supplementation on anthropometry and blood pressure in mid-childhood in Nepal: follow-up of a double-blind randomised controlled trial

Background

In 2002–04, we did a randomised controlled trial in southern Nepal, and reported that children born to mothers taking multiple micronutrient supplements during pregnancy had a mean birthweight 77 g greater than children born to mothers taking iron and folic acid supplements. Children born to mothers in the study group were a mean 204 g heavier at 2·5 years of age and their systolic blood pressure was a mean 2·5 mm Hg lower than children born to mothers in the control group. We aimed to follow up the same children to mid-childhood (age 8·5 years) to investigate whether these differences would be sustained.

Methods

For this follow-up study, we identified children from the original trial and measured anthropometry, body composition with bioelectrical impedance (with population-specific isotope calibration), blood pressure, and renal dimensions by ultrasound. We documented socioeconomic status, household food security, and air pollution. Main outcomes of the follow-up at 8 years were Z scores for weight-for-age, height-for-age, and body-mass index (BMI)-for-age according to WHO Child Growth Standards for children aged 5–19 years, and blood pressure. This study is registered with the International Standard Randomised Controlled Trial register, number ISRCTN88625934.

Findings

Between Sept 21, 2011, and Dec 7, 2012, we assessed 841 children (422 in the control group and 419 in the intervention group). Unadjusted differences (intervention minus control) in Z scores were 0·05 for weight-for-age (95% CI −0·09 to 0·19), 0·02 in height-for-age (−0·10 to 0·15), and 0·04 in BMI-for-age (−0·09 to 0·18). We recorded no difference in blood pressure. Adjusted differences were similar for all outcomes.

Interpretation

We recorded no differences in phenotype between children born to mothers who received antenatal multiple micronutrient or iron and folate supplements at age 8·5 years. Our findings did not extend to physiological differences or potential longer-term effects.

Funding

The Wellcome Trust.