Acute exposure to wood smoke from incomplete combustion – indications of cytotoxicity. Particle and Fibre Toxicology, Oct 2015.

Authors: Ala Muala, Gregory Rankin, Maria Sehlstedt

Background – Smoke from combustion of biomass fuels is a major risk factor for respiratory disease, but the underlying mechanisms are poorly understood. The aim of this study was to determine whether exposure to wood smoke from incomplete combustion would elicit airway inflammation in humans.

Methods – Fourteen healthy subjects underwent controlled exposures on two separate occasions to filtered air and wood smoke from incomplete combustion with PM 1 concentration at 314 μg/m 3 for 3 h in a chamber. Bronchoscopy with bronchial wash (BW), bronchoalveolar lavage (BAL) and endobronchial mucosal biopsies was performed after 24 h. Differential cell counts and soluble components were analyzed, with biopsies stained for inflammatory markers using immunohistochemistry. In parallel experiments, the toxicity of the particulate matter (PM) generated during the chamber exposures was investigated in vitro using the RAW264.7 macrophage cell line.

Results – Significant reductions in macrophage, neutrophil and lymphocyte numbers were observed in BW (p < 0.01, <0.05, <0.05, respectively) following the wood smoke exposure, with a reduction in lymphocytes numbers in BAL fluid (<0.01. This unexpected cellular response was accompanied by decreased levels of sICAM-1, MPO and MMP-9 (p < 0.05, <0.05 and <0.01). In contrast, significant increases in submucosal and epithelial CD3+ cells, epithelial CD8+ cells and submucosal mast cells (p < 0.01, <0.05, <0.05 and <0.05, respectively), were observed after wood smoke exposure. The in vitro data demonstrated that wood smoke particles generated under these incomplete combustion conditions induced cell death and DNA damage, with only minor inflammatory responses.

Conclusions – Short-term exposure to sooty PAH rich wood smoke did not induce an acute neutrophilic inflammation, a classic hallmark of air pollution exposure in humans. While minor proinflammatory lymphocytic and mast cells effects were observed in the bronchial biopsies, significant reductions in BW and BAL cells and soluble components were noted. This unexpected observation, combined with the in vitro data, suggests that wood smoke particles from incomplete combustion could be potentially cytotoxic. Additional research is required to establish the mechanism of this dramatic reduction in airway leukocytes and to clarify how this acute response contributes to the adverse health effects attributed to wood smoke exposure.


Bringing clean, safe, affordable cooking energy to households across Africa: an agenda for action, 2015.

Authors: Fiona Lambe, Marie Jürisoo, Hannah Wanjiru and Jacqueline Senyagwa. SEI.

This paper presents an overview of current household energy trends in Africa, and the reasons why access to modern cooking facilities remains so low. It then presents the latest evidence on the health, environmental and socio-economic impacts of traditional biomass use in sub-Saharan Africa, with a dedicated section on the particular challenges associated with charcoal as a household cooking fuel. Next, it highlights where interventions to provide access to clean and improved cooking options are having a positive impact, drawing on case studies in Mali, Ghana, Kenya and Ethiopia.

Low correlation between household carbon monoxide and particulate matter concentrations from biomass-related pollution in three resource-poor settings. Environmental Research, Volume 142, October 2015, Pages 424–431.

Authors: E. Klasen, et al.

Household air pollution from the burning of biomass fuels is recognized as the third greatest contributor to the global burden of disease. Incomplete combustion of biomass fuels releases a complex mixture of carbon monoxide (CO), particulate matter (PM) and other toxins into the household environment. Some investigators have used indoor CO concentrations as a reliable surrogate of indoor PM concentrations; however, the assumption that indoor CO concentration is a reasonable proxy of indoor PM concentration has been a subject of controversy.

We sought to describe the relationship between indoor PM2.5 and CO concentrations in 128 households across three resource-poor settings in Peru, Nepal, and Kenya. We simultaneously collected minute-to-minute PM2.5 and CO concentrations within a meter of the open-fire stove for approximately 24 h using the EasyLog-USB-CO data logger (Lascar Electronics, Erie, PA) and the personal DataRAM-1000AN (Thermo Fisher Scientific Inc., Waltham, MA), respectively. We also collected information regarding household construction characteristics, and cooking practices of the primary cook. Average 24 h indoor PM2.5 and CO concentrations ranged between 615 and 1440 μg/m3, and between 9.1 and 35.1 ppm, respectively. Minute-to-minute indoor PM2.5 concentrations were in a safe range (<25 μg/m3) between 17% and 65% of the time, and exceeded 1000 μg/m3 between 8% and 21% of the time, whereas indoor CO concentrations were in a safe range (<7 ppm) between 46% and 79% of the time and exceeded 50 ppm between 4%, and 20% of the time.

Overall correlations between indoor PM2.5 and CO concentrations were low to moderate (Spearman ρbetween 0.59 and 0.83). There was also poor agreement and evidence of proportional bias between observed indoor PM2.5 concentrations vs. those estimated based on indoor CO concentrations, with greater discordance at lower concentrations. Our analysis does not support the notion that indoor CO concentration is a surrogate marker for indoor PM2.5 concentration across all settings. Both are important markers of household air pollution with different health and environmental implications and should therefore be independently measured.

A cross-sectional study of exhaled carbon monoxide as a biomarker of recent household air pollution exposure. Environmental Research, Volume 143, Part A, November 2015, Pages 107–111.

Authors: Alison Lee, Tiffany R. Sanchez, et al.

Rationale – Household air pollution causes 3.5 million deaths annually. Personal exposure assessments required for examining health associations are expensive and require technical expertize, limiting the quality of research in resource-poor settings.

Objectives – To assess the feasibility of exhaled carbon monoxide and its relationship to continuous personal carbon monoxide monitoring and markers of respiratory health in female cooks primarily cooking with biomass fuels in Araihazar, Bangladesh.

Methods and measure – For a 24-h period, exhaled carboxyhemoglobin (eCOHb) % saturation was measured before and after each cooking episode while simultaneous 24-h personal carbon monoxide monitoring was conducted. The Coburn–Forester–Kane (CFK) equation was used to convert continuous personal CO exposures to predicted COHb % saturation. Respiratory symptoms were assessed by St. George’s Respiratory Questionnaire, airway inflammation measured by exhaled breath condensate pH, and lung function determined by spirometry. Spearman’s correlation was used to examine the relationship between eCOHb and CKF-derived COHb, EBC pH, and lung function variables. eCOHb % saturation was dichotomized around the median and odds ratios calculated for each respiratory symptom.

Main results – Measurement of eCOHb % saturation is feasible in a resource-poor setting. eCOHb % saturation responds to cooking episodes and demonstrates consistency when measured at the same time point 24-h later, suggesting that eCOHb may be a sensitive biomarker of recent HAP exposures.

Household Air Pollution and Under-Five Mortality in Bangladesh (2004–2011). Int. J. Environ. Res. Public Health, Oct 2015.

Authors: Sabrina Naz, Andrew Page and Kingsley Emwinyore Agho

Household air pollution (HAP) is one of the leading causes of respiratory illness and deaths among children under five years in Bangladesh. This study investigates the association between HAP from cooking fuel and under-five mortality using Bangladesh Demographic and Health Survey (BDHS) datasets over the period 2004–2011 (n = 18,308 children), and the extent to which this association differed by environmental and behavioral factors affecting level of exposure.

The association between HAP and neonatal (age between 0–28 days), infant (age between 0 and 11 months) and under–five (age between 0 and 59 months) mortality was examined using multilevel logistic regression models. HAP was not strongly associated with overall neonatal (OR = 1.49, 95% CI = 1.01–2.22, p = 0.043), infant (OR = 1.27, 95% CI = 0.91–1.77, p = 0.157) or under-five mortality (OR = 1.14, 95% CI = 0.83–1.55, p = 0.422) in the context of overall decreasing trends in under-five mortality.

The association was stronger for households with an indoor kitchen using polluting fuels, and in women who had never breastfed. Reductions in exposure to pollution from cooking fuel, given it is a ubiquitous and modifiable risk factor, can result in further declines in under-five mortality with household design and behavioural interventions.

Cooking with gas: How children in the developing world benefit from switching to LPG, 2015.

Author: Lisa M Thompson. Report developed for the World LPG Association.

To incentivise the full adoption of LPG for cooking, strategies such as generating demand for LPG stoves, strengthening the supply-chain of LPG stoves and fuel, and developing regulation mechanisms to ensure safety of LPG are essential. Creating a supportive infrastructure for operating, inspecting and maintaining LPG and other clean stove technologies are necessary during the transitional period.

Fully displacing the use of traditional cookstoves and open fires is a considerable challenge, especially for the poorest of poor who ration their earnings on a daily basis and usually do not have money left over for large household purchases. Policymakers in the energy, health, and environment sectors need to advance strategies to increase affordable and accessible clean cookstoves and fuels for the poorest sectors–those who pay the highest cost for fuel, relative to their income, use the lowest quality stove, and experience the highest costs of poverty in terms of poor health.


The Lighting Transition in Africa: From Kerosene to LED and the Emerging Dry-Cell Battery Problem, 2015.

Authors: Gunther Bensch, Jörg Peters, Maximiliane Sievert. Ruhr-Universität Bochum (RUB), Department of Economics.

Non-electrified people in Africa, still more than 500 million today, have been using kerosene and candles for their lighting purposes for decades. The lighting quality of these sources is low and in particular kerosene usage is associated with harmful soot emissions. Alleviating this grievance has always been a major goal of electrification programs.

The present paper shows that in recent years a transition has taken place among the rural non-electrified population in Africa: without any external support from governmental or non-governmental organisations people have replaced kerosene lamps and candles through LED lamps, which are mostly powered by dry-cell batteries.LED lamps are available in rural shops virtually everywhere and provide brighter and cleaner lighting than traditional lamps.

The downside of this massive increase of LED usage is a soaring consumption of dry-cell batteries. Because of the toxic content of many dry-cell batteries and since people dispose of discharged batteries in appropriately in latrines or the nature, harmful effects on the local environment are likely. We conclude by suggesting that rapid action is needed to put in place an effective waste management system.

Reducing global health risks through mitigation of short-lived climate pollutants: Scoping report for policymakers, 2015. World Health Organization.

Author: Noah Scovronick

This WHO report highlights the urgent need to reduce emissions of black carbon, ozone and methane – as well as carbon dioxide – which all contribute to climate change. Black carbon, ozone and methane – frequently described as short-lived climate pollutants (SLCPs) – not only produce a strong global warming effect, they contribute significantly to the more than 7 million premature deaths annually linked to air pollution.

Indoor air pollutant exposure for life cycle assessment: regional health impact factors for households. Environ. Sci. Technol, October 7, 2015

Authors: Ralph K Rosenbaum, Arjen Meijer, Evangelia Demou, Stefanie Hellweg, Olivier Jolliet, Nicholas L. Lam, Manuele Margni, and Thomas E. McKone

Human exposure to indoor pollutant concentrations is receiving increasing interest in Life Cycle Assessment (LCA). We address this issue by incorporating an indoor compartment into the USEtox model, as well as by providing recommended parameter values for households in four different regions of the world differing geographically, economically, and socially. With these parameter values, intake fractions and comparative toxicity potentials for indoor emissions of dwellings for different air tightness levels were calculated.

The resulting intake fractions for indoor exposure vary by two orders of magnitude, due to the variability of ventilation rate, building occupation and volume. To compare health impacts as a result of indoor exposure with those from outdoor exposure, the indoor exposure characterization factors determined with the modified USEtox model were applied in a case study on cooking in non-OECD countries. This study demonstrates the appropriateness and significance of integrating indoor environments into LCA, which ensures a more holistic account of all exposure environments and allows for a better accountability of health impacts. The model, intake fractions, and characterization factors are made available for use in standard LCA studies via and in standard LCA software.

Microbiological Evaluation of Household Drinking Water Treatment in Rural China Shows Benefits of Electric Kettles: A Cross-Sectional Study. PLoS One. Sept 2015.

Authors: Alasdair Cohen, Yong Tao, Qing Luo, Gemei Zhong, Jeff Romm, John M. Colford, Jr, and Isha Ray

Background – In rural China ~607 million people drink boiled water, yet little is known about prevailing household water treatment (HWT) methods or their effectiveness. Boiling, the most common HWT method globally, is microbiologically effective, but household air pollution (HAP) from burning solid fuels causes cardiovascular and respiratory disease, and black carbon emissions exacerbate climate change. Boiled water is also easily re-contaminated. Our study was designed to identify the HWT methods used in rural China and to evaluate their effectiveness.

Methods – We used a geographically stratified cross-sectional design in rural Guangxi Province to collect survey data from 450 households in the summer of 2013. Household drinking water samples were collected and assayed for Thermotolerant Coliforms (TTC), and physicochemical analyses were conducted for village drinking water sources. In the winter of 2013–2104, we surveyed 120 additional households and used remote sensors to corroborate self-reported boiling data.

Findings – Our HWT prevalence estimates were: 27.1% boiling with electric kettles, 20.3% boiling with pots, 34.4% purchasing bottled water, and 18.2% drinking untreated water (for these analyses we treated bottled water as a HWT method). Households using electric kettles had the lowest concentrations of TTC (73% lower than households drinking untreated water). Multilevel mixed-effects regression analyses showed that electric kettles were associated with the largest Log10TTC reduction (-0.60, p<0.001), followed by bottled water (-0.45, p<0.001) and pots (-0.44, p<0.01). Compared to households drinking untreated water, electric kettle users also had the lowest risk of having TTC detected in their drinking water (risk ratio, RR = 0.49, 0.34–0.70, p<0.001), followed by bottled water users (RR = 0.70, 0.53–0.93, p<0.05) and households boiling with pots (RR = 0.74, 0.54–1.02, p = 0.06).

Conclusion – As far as we are aware, this is the first HWT-focused study in China, and the first to quantify the comparative advantage of boiling with electric kettles over pots. Our results suggest that electric kettles could be used to rapidly expand safe drinking water access and reduce HAP exposure in rural China.