Umeå University's logo

Around one-fourth of the global population lacks access to clean fuels and technologies for cooking, most of them living in low- and middle-income countries. Reliance on rudimentary and inefficient biomass cookstoves results in high pollutant concentrations that adversely affect the health of those exposed to indoor air pollution, the environment, and the climate. In this study, we systematically reviewed the literature on aerosol and particle properties from biomass cookstoves of relevance to health, climate and the environment. We identified 187 articles reporting aerosol characterization (i.e. particulate mass or number concentrations, or particle size distributions). Of these, 82 presented detailed particle characterization (e.g. chemical composition), thus selected for further analysis. Articles were classified based on the reported particle properties and the study type and location, which allowed mapping research efforts to date and identifying major knowledge gaps. Most reviewed studies (39 articles) on particle properties reported particulate organic and elemental carbon composition. Despite considerable variability, the EC/TC ratio generally varied in the range of 0.1-0.4 for all cookstove technologies, indicating that organic carbon is the dominating PM fraction in biomass cookstove emissions. Findings from this systematic review highlight the need for further studies on particle properties from biomass cookstoves that use a multidimensional approach simultaneously combining several properties and different cookstove-fuel combinations. We also assessed the policy landscape, including the three main global policies concerning biomass cookstove emissions, and evaluated whether those policies included the state of the knowledge on particle properties and their adverse effects on human health, climate, and the environment. We finally identify key aspects that future policies should integrate, and critical knowledge gaps that must be filled to advance the overall development of the field. Notable was that field studies consistently report particle emission factors (PM_2.5) higher than the ones determined under laboratory conditions, for example, an average of 8.9 g/kg_fuel (field) compared to 5.2 g/kg_fuel (lab) for traditional cookstoves and 4.0 g/kg_fuel (field) compared to 1.3 g/kg_fuel (lab) for advanced cookstoves. Cookstove manufacturers, practitioners, policymakers, and society in general will benefit from a solid knowledge base regarding particle properties from biomass cookstoves and their related adverse effects on human health, climate, and the environment.

Globally, 3 billion people rely on solid biomass fuel for their everyday cooking, most often using inefficient cooking practices, leading to high exposure levels of household air pollution. This is subsequently associated with negative health and climate impact. Further, the inefficient use of biomass fuels applies pressure on natural forests, resulting in deforestation, loss of biodiversity, and soil degradation. Improved cookstove technologies and biomass fuels are being promoted to mitigate these issues. However, limited knowledge exists about how the interaction between stove technology and new fuels affects the physical and chemical properties of particulate emissions. In this study, the emission performance of four cookstove technologies in combination with five fuels was evaluated in a laboratory setup, applying a modified water boiling test with a hood dilution system for flue gas sampling. Filter sampling was applied to determine the emissions of fine particulate matter (PM₁) and for subsequent analysis of polycyclic aromatic compounds (PAC), organic- and elemental carbon, and inorganic composition. Particle mass size distribution was determined by using a 13-stage low-pressure cascade impactor. Online instruments were used to determine gaseous emissions (e.g., CO, CH₄, and BTX) as well as particle number size distribution. The results show that both the stove design and fuel properties influence the total emissions as well as the physiochemical PM characteristics. It was further seen that the impact of fuel on the PM properties did not translate linearly among the different stove technologies. This implies that each stove should be tested with various fuels to determine both the total emissions and fuel suitability.

Most people in rural sub-Saharan Africa lack access to electricity and rely on traditional, inefficient, and polluting cooking solutions that have adverse impacts on both human health and the environment. Here, we propose a novel integrated agroforestry-bioenergy system that combines sustainable biomass production in sequential agroforestry systems with biomass-based cleaner cooking solutions and rural electricity production in small-scale combined heat and power plants and estimate the biophysical system outcomes. Despite conservative assumptions, we demonstrate that on-farm biomass production can cover the household’s fuelwood demand for cooking and still generate a surplus of woody biomass for electricity production via gasification. Agroforestry and biochar soil amendments should increase agricultural productivity and food security. In addition to enhanced energy security, the proposed system should also contribute to improving cooking conditions and health, enhancing soil fertility and food security, climate change mitigation, gender equality, and rural poverty reduction.

In this StoyMap we will be sharing our reflections about our research visit to the Netherlands. Our visit funded by  Umeå Transformation Research Initiative  aims to foster cross-disciplinary synergies among early career researchers, interact with innovative research environments, as well as to expand our collaboration networks around sustainability science. By doing so, we aim to build capacities for transformative research. We thank all our hosts for their time and enthusiasm.

Background: Exposure to wood smoke has been shown to contribute to adverse respiratory health effects including airway infections, but the underlying mechanisms are unclear. A preceding study failed to confirm any acute inflammation or cell influx in bronchial wash (BW) or bronchoalveolar lavage (BAL) 24 h after wood smoke exposure but showed unexpected reductions in leukocyte numbers. The present study was performed to investigate responses at an earlier phase, regarding potential development of acute inflammation, as well as indications of cytotoxicity.

Methods: In a double-blind, randomised crossover study, 14 healthy participants were exposed for 2 h to filtered air and diluted wood smoke from incomplete wood log combustion in a common wood stove with a mean particulate matter concentration of 409 µg/m3. Bronchoscopy with BW and BAL was performed 6 h after exposure. Differential cell counts, assessment of DNA-damage and ex vivo analysis of phagocytic function of phagocytosing BAL cells were performed. Wood smoke particles were also collected for in vitro toxicological analyses using bronchial epithelial cells (BEAS-2B) and alveolar type II-like cells (A549).

Results: Exposure to wood smoke increased BAL lactate dehydrogenase (LDH) (p = 0.04) and reduced the ex vivo alveolar macrophage phagocytic capacity (p = 0.03) and viability (p = 0.02) vs. filtered air. BAL eosinophil numbers were increased after wood smoke (p = 0.02), while other cell types were unaffected in BW and BAL. In vitro exposure to wood smoke particles confirmed increased DNA-damage, decreased metabolic activity and cell cycle disturbances.

Conclusions: Exposure to wood smoke from incomplete combustion did not induce any acute airway inflammatory cell influx at 6 h, apart from eosinophils. However, there were indications of a cytotoxic reaction with increased LDH, reduced cell viability and impaired alveolar macrophage phagocytic capacity. These findings are in accordance with earlier bronchoscopy findings at 24 h and may provide evidence for the increased susceptibility to infections by biomass smoke exposure, reported in population-based studies.

Over 640 million people in Africa are expected to rely on solid-fuels for cooking by 2040. In Western Kenya, cooking inefficiently persists as a major cause of burden of disease due to household air pollution. Efficient biomass cooking is a local-based renewable energy solution to address this issue. The Life-Cycle Assessment tool Simapro 8.5 is applied for analyzing the environmental impact of four biomass cooking strategies for the Kisumu County, with analysis based on a previous energy modelling study, and literature and background data from the Ecoinvent and Agrifootprint databases applied to the region. A Business-As-Usual scenario (BAU) considers the trends in energy use until 2035. Transition scenarios to Improved Cookstoves (ICS), Pellet-fired Gasifier Stoves (PGS) and Biogas Stoves (BGS) consider the transition to wood-logs, biomass pellets and biogas, respectively. An Integrated (INT) scenario evaluates a mix of the ICS, PGS and BGS. In the BGS, the available biomass waste is sufficient to be upcycled and fulfill cooking demands by 2035. This scenario has the lowest impact on all impact categories analyzed followed by the PGS and INT. Further work should address a detailed socio-economic analysis of the analyzed scenarios.

Over 640 million people in Africa are expected to rely on solid-fuels for cooking by 2040. In Western Kenya, cooking inefficiently persists as a major cause of burden disease due to household air pollution. The Long-Range Energy Alternatives Planning (LEAP) system and the Life-Cycle Assessment tool Simapro 8.5 were applied for analyzing biomass strategies for the region. The calculation of the residential energy consumption and emissions was based on scientific reviews and original data from experimental studies. The research shows the effect of four biomass strategies on the reduction of wood fuel use and short-lived climate pollutant emissions. A Business As Usual scenario (BAU) considered the trends in energy use until 2035. Transition scenarios to Improved Cookstoves (ICS), Pellet-fired Gasifier Stoves (PGS) and Biogas Stoves (BGS) considered the transition to wood-logs, biomass pellets and biogas, respectively. An Integrated (INT) scenario evaluated a mix of the ICS, PGS and BGS. The study shows that, energy use will increase by 8% (BGS), 20% (INT), 26% (PGS), 42% (ICS) and 56% (BAU). The BGS has the lowest impact on global warming, particle formation, terrestrial acidification, fossil resource scarcity, water consumption, as well as on eutrophication followed by the PGS and INT.

Traditional cooking is today's largest global environmental health risk. Over 640 million people in Africa are expected to rely on biomass for cooking by 2040. In Kenya, cooking inefficiently with wood and charcoal persists as a cause of deforestation and household air pollution. This research analyses the effects of four biomass cookstove strategies on reducing air pollutant emissions in Kisumu County between 2015 and 2035 using the Long-Range Energy Alternatives Planning system. The Business as Usual scenario (BAU) was developed considering the historical trends in household energy use. Energy transition scenarios to Improved Cookstoves (ICS), Pellet Gasifier Stoves (PGS) and Biogas Stoves (BGS) were applied to examine the impact of these systems on energy savings and air pollution mitigation. An integrated scenario (INT) was evaluated as a mix of the ICS, PGS and BGS. The highest energy savings, in relation to the BAU, are achieved in the BGS (30.9%), followed by the INT (23.5%), PGS (19.4%) and ICS (9.2%). The BGS offers the highest reduction in the GHG (37.6%), CH4 (94.3%), NMVOCs (85.0%), CO (97.4%), PM2.5 (64.7%) and BC (48.4%) emissions, and the PGS the highest reduction in the N2O (83.0%) and NOx (90.7%) emissions, in relation to the BAU.