Elizabeth Tilley

Last Name

Tilley

First Name

Elizabeth

ORCID

0000-0002-2095-9724

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09746 - Tilley, Elizabeth / Tilley, Elizabeth

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Publications 1 - 10 of 60

Light absorbing carbonaceous aerosols: Concentrations and sources in an under-monitored setting
Vijay, Saloni; Chilunga, Hope Kelvin; Schöbitz, Lars; et al. (2025)
Ecotoxicology and Environmental Safety
Light-absorbing carbonaceous (LAC) aerosols, particularly black carbon (BC), impact human health and climate, yet their sources are understudied in sub-Saharan Africa (SSA). This study presents the first source apportionment of LAC aerosols in Malawi, using locally determined Absorption Ångström Exponent (AAE) values for the first time in the SSA region. From May to August 2023, mobile monitoring covered eight settlements and highways, with stationary monitoring at two sites in Blantyre, Malawi’s second-largest city. We used the MA200 micro-aethalometer to measure equivalent black carbon (eBC) as a BC proxy. Fossil fuel and biomass burning sources were distinguished based on locally determined AAE thresholds (<1.29 for fossil fuel, >1.63 for biomass and intermediate values indicating mix of both). Stationary monitoring revealed mean eBC levels of 4.1 ± 4.1 µg m⁻³ in planned and 3.6 ± 2.6 µg m⁻³ in unplanned settlements. Mobile monitoring showed spatial variations, with highways averaging 11.3 µg m⁻³ and settlements mean ranging from 2.4 to 9.9 µg m-³ eBC. Across settlements, biomass burning contributed 7 %–46 %, and fossil fuel combustion contributed 10 %–73 % of the total average eBC. The dominant eBC source between fossil fuel and biomass remained consistent across AAE values 1.21–1.37 for fossil fuel and 1.55–1.71 for biomass in sensitivity analysis, except in one settlement. Blantyre’s eBC concentrations were comparable to some large and more populated urban cities in SSA, highlighting air quality challenges as the city urbanizes. The study emphasizes area-specific interventions and demonstrates a transferable source apportionment methodology for diverse urban contexts globally.
Seasonal Preferences and Alternatives for Domestic Water Sources: A Prospective Cohort Study in Malawi
Cassivi, Alexandra; Tilley, Elizabeth; Waygood, Owen; et al. (2021)
ACS ES&T Water
Access to a sufficient quantity of safe water is widely recognized as fundamental to ensure health and prevent water- and excreta-related diseases. The objective of this study is to analyze seasonal variations in household preferences and alternatives in accessing domestic water, including for drinking, and to identify predictors for the use of multiple water sources. A prospective cohort study was conducted in Malawi, and data were collected using structured household questionnaires and water quality testing. Results showed that households fetching water were more likely to rely on multiple water sources during the rainy season, compared to the dry season. When access to a single water source is insufficient, and/or the main water source is broken or not functional, households use additional water sources that are more likely to be contaminated or distant as a coping strategy. Water source reliability (i.e., functionality and availability) and proximity to water sources (i.e., time to collect water, waiting time) were found to be the most important factors influencing households’ preferences. Ensuring reliable and continuous access, throughout the seasons, to at least a single water source that is located in proximity to the household is a key intervention to reduce the fetching burden.
Effect of Various Organic Fertilisers on Phosphorus Mineralisation, Use Efficiency and Maize Yield
Mnthambala, Frank; Tilley, Elizabeth; Tyrrel, Sean; et al. (2022)
Resources
When soils are phosphorus (P) deficient, external sources in the form of fertilisers have to be applied to increase crop yields. The world depends on mined sources for P fertilisers, and recent reports indicate that an increase in the human population has led to rising demand for P fertilisers, making its future supply uncertain. A low supply of chemical P fertilisers may lead to food insecurity. Although the efficacy of organic sources of P is unclear, organic waste materials containing P can potentially replace inorganic P sources. Previously, organic fertilisers have been used to supply N and even P, but the application rates were mostly N based, resulting in inconsistent and comparable results. This research was conducted to understand P mineralisation and the availability of the P-based organic fertilisers. The results showed that available P in the soil at 3 weeks accounted for 50%, 6 weeks accounted for 49%, and 9 weeks counted for 46% of the maize yield. The organic P sources maintained soil available P above the threshold available P value in Malawi. The P sources did not affect the maize P use efficiency (PUE). The results indicate that organic P sources could be used as an alternative fertiliser for maize production in Malawi.
Looking beyond technology: An integrated approach to water, sanitation and hygiene in low income countries
Tilley, Elizabeth; Strande, Linda; Lüthi, Christoph; et al. (2014)
Environmental Science & Technology
Financial Transfers and Responsibility in Faecal Sludge Management Chains
Tilley, Elizabeth; Dodane, Pierre-Henri (2014)
Faecal sludge management : systems approach for implementation and operation
Open waste burning leads to significantly high black carbon exposure amongst burners
Vijay, Saloni; Khonje, Lennox; Chatha, Mwaiwathu Laurent; et al. (2025)
EGUsphere
Globally, about 14% of households have no option but to burn their waste. Open waste burning is a significant source of black carbon (BC) emissions, yet the exposure of those engaged in this practice has not been interrogated. This study provides the first quantification of personal exposure to BC emissions from open waste burning, revealing critical insights into the potential health risks faced by individuals engaged in this practice. Between November–December 2023, we conducted a comprehensive field study in Blantyre, Malawi, monitoring BC exposure among 46 volunteers from 23 households over approximately 20 hours on the day waste was burned at their household. Within each household, one individual responsible for burning waste and one non-burner wore MicroAeth MA200 monitors to capture personal exposure data. To summarize exposure, the average BC concentration was calculated for each a) monitoring period, b) for burning times, and c) for non-burning times. The median of these averages was then used to characterize exposure levels. Results showed that waste burners experienced significantly higher BC exposure than non-burners during both burning periods and the overall monitoring period (Wilcoxon signed rank test, p = 0.04). During burning, the median BC exposure for burners was 12.8 μg/m³, over four times higher than the median exposure of non-burners at 2.9 μg/m³. The median BC exposure for burners during the 20-hour monitoring period was 5.1 μg/m³, compared to 3.0 μg/m³ for non-burners. Notably, BC exposure levels during non-burning periods were statistically indistinguishable between burners and non-burners (Wilcoxon signed rank test, p = 0.44), with median exposures of 3.6 μg/m³ and 2.6 μg/m³, respectively. This study highlights the extreme BC exposure faced by individuals actively burning waste, and underscores the health risks associated with this practice and the need for interventions to mitigate exposure.
Not just a donor learning experience: Exploring failure, accountability, and harm within a large aid funded biogas project in Malawi
Williams-Werther, Natalie Alice; Kalina, Marc; Kwangulero, Jonathan; et al. (2025)
Energy Research & Social Science
In Africa, investments in domestic biogas projects have yielded mixed results, with numerous poor outcomes reported. While many commonly cited barriers contribute to these failures, the role of structural issues rooted in development and aid remains underexplored and poorly understood. This investigation examined 72 tarpaulin-based biogas digesters funded by UNDP across seven districts in Malawi, which experienced rapid failure shortly after implementation. Unlike many biogas studies focusing on symptoms of failure this research focussed specifically on the governance and decision-making processes that led to failure. In-depth interviews with 65 of the beneficiaries and 15 stakeholders revealed that the project failed due to poor management, unclear leadership, and weak governance. The digesters were hastily installed in remote areas that had no local expertise just before project funding expired, amidst suspected corruption and a lack of biogas expertise among all project stakeholders. The project lacked accountability to beneficiaries, leaving them powerless to influence change in their own development project. Far from being a harmless learning opportunity, as it was described by some of the project's stakeholders, the project caused harm to beneficiaries who invested limited resources into the poorly executed biogas intervention. This study challenges the typical user-centred focus of failure analyses and underscores the importance of focusing on structural causes of failure. By focussing on systemic issues, we can foster more informed discussions on biogas projects. Moreover, this approach enables accountability to beneficiaries, which can inform decision-making regarding potentially flawed projects and help to hold institutions responsible for harm caused.
Reducing water quality data inequities: A low-cost to a membrane filtration technique for the quantification of Escherichia coli in drinking water in low-resource contexts
Zimmer, Camille; Boyer, Rachel; Cassivi, Alexandra; et al. (2025)
PLOS Water
Access to safe drinking water is a recognized human right and a policy priority, reflected in the United Nations’ Sustainable Development Goals (SDGs). To monitor progress on SDG Target 6.1—safely managed drinking water services—many countries now incorporate Escherichia coli water quality testing into nationally representative household surveys, including UNICEF’s Multiple Indicator Cluster Surveys (MICS). The objective of this study was to evaluate multiple aspects of existing MICS water quality testing techniques. A low-cost filtration kit (~$\$$60 compared to ~$\$$1200 for the standard kit) was piloted during a water quality study in Southern Malawi. The low-cost filtration kit performed well with no breakage, leakage or stability issues reported. An existing MICS quality control measure was also assessed. Results support the current practice of using pre-tested locally purchased bottled water to undertake “blank” negative quality control testing. The current practice of having enumerators count E. coli colonies was investigated and was found to be acceptable and valid. To increase the storage capacity of the belt incubation method, a reduced (18-vs. 24-hour) incubation time was investigated. If the purpose is to classify results by risk categories, it would be advisable to incubate samples for the additional 6 hours if after 18 hours a count is observed of only 1 or 2 CFU/100 mL lower than the cut-off for the next highest risk category. Overall, results were encouraging and support the widespread use of the low-cost filtration kit, with potentially significant cost savings. However, we recommend further research to investigate and quantify the impacts of an abbreviated incubation time on water quality results.
Willingness to pay for and economic feasibility of solid waste management in Cape Maclear, Malawi
Abgottspon, Elena; Freihardt, Jan; Tkaczuk, Jakub; et al. (2025)
Resources, Conservation & Recycling Advances
Improving solid waste management (SWM) can better public health locally and mitigate climate change globally. However, it requires thorough financing and business models. This study assessed the willingness to pay (WTP) of four stakeholder groups in the village Cape Maclear, Malawi, using the double-bounded dichotomous choice contingent valuation method as well as direct questions. Households (N 259) would be willing to pay an average of MWK 1507 (USD 0.90) per month if they did not have to separate their waste themselves, as opposed to MWK 899 (USD 0.54) per month if they had to separate their waste at the collection point. Lodges were willing to pay USD 13.00 per month for their own waste management and an additional USD 4.22 for public waste removal. The WTP of businesses was assumed to be zero due to an unrepresentative sample. Tourists were found to have an average WTP of USD 1.75 per day. We recommend a sustainable business model based on all cost and revenue streams of the system. Thereby, tourists show the greatest potential. Nevertheless, it is recommended to make the monthly operation of the system independent from external sources, but to use these sources for long-term investments and infrastructure improvements.
Overcoming Barriers to Exclusive Breastfeeding in Lao PDR: Social Transfer Intervention Randomised Controlled Trial
Karimian-Marnani , Najmeh; Tilley, Elizabeth; Wallenborn , Jordyn T. (2025)
Nutrients
Background/Objectives: Despite the numerous health benefits of exclusive breastfeeding (EBF) for the infant and the mother, EBF rates in Lao People’s Democratic Republic, Lao PDR, remain at 40%. We investigate how barriers to EBF were overcome by a social transfer intervention. Methods: Data from the Social Transfers for Exclusive Breastfeeding ongoing randomised controlled trial (RCT) (n = 298) in Vientiane, Lao PDR, was used. Mothers in the RCT were randomised equally into a control group, an unconditional transfer group and a conditional transfer group and followed up to six months (n = 280). We used logistic and Cox proportional hazards regression models to investigate the association of predictor variables with EBF at six months and the risk of EBF cessation in each of the three groups. Results: Greater breastfeeding self-efficacy increased the odds of EBF at six months in both intervention groups (unconditional transfer OR 1.39 [95% CI 1.09, 1.87, p = 0.02] and conditional transfer OR 1.26 [1.01, 1.61, p = 0.05]) and reduced the risk of EBF cessation (unconditional transfer HR 0.87 [0.77, 0.98, p = 0.02]). Maternal secondary and tertiary education in the intervention groups showed higher odds of EBF at six months and lower EBF cessation risk. Participants in the intervention group that intended to exclusively breastfeed in pregnancy showed a reduced EBF cessation risk in both intervention groups. Conclusions: Social transfers helped overcome the exclusive breastfeeding barrier of a higher education level and working status and improved EBF outcomes for mothers who intended to exclusively breastfeed and wanted the pregnancy. Breastfeeding self-efficacy positively influences EBF outcome, regardless of whether the mother received a social transfer or not.

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Elizabeth Tilley

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