Michael Johnson

Household light makes global heat: High black carbon emissions from kerosene wick lamps

Kerosene-fueled wick lamps used in millions of developing-country households are a significant but overlooked source of black carbon (BC) emissions. We present new laboratory and field measurements showing that 7-9% of kerosene consumed by widely used simple wick lamps is converted to carbonaceous particulate matter that is nearly pure BC. These high emission factors increase previous BC emission estimates from kerosene by 20-fold, to 270 Gg/year (90% uncertainty bounds: 110, 590 Gg/year). Aerosol climate forcing on atmosphere and snow from this source is estimated at 22 mW/m² (8, 48 mW/m²), or 7% of BC forcing by all other energy-related sources. Kerosene lamps have affordable alternatives that pose few clear adoption barriers and would provide immediate benefit to user welfare. The net effect on climate is definitively positive forcing as coemitted organic carbon is low. No other major BC source has such readily available alternatives, definitive climate forcing effects, and cobenefits. Replacement of kerosene-fueled wick lamps deserves strong consideration for programs that target short-lived climate forcers.

Assessing the Impact of Water Filters and Improved Cook Stoves on Drinking Water Quality and Household Air Pollution: A Randomised Controlled Trial in Rwanda

Diarrhoea and respiratory infections remain the biggest killers of children under 5 years in developing countries. We conducted a 5-month household randomised controlled trial among 566 households in rural Rwanda to assess uptake, compliance and impact on environmental exposures of a combined intervention delivering high-performance water filters and improved stoves for free. Compliance was measured monthly by self-report and spot-check observations. Semi-continuous 24-h PM2.5 monitoring of the cooking area was conducted in a random subsample of 121 households to assess household air pollution, while samples of drinking water from all households were collected monthly to assess the levels of thermotolerant coliforms. Adoption was generally high, with most householders reporting the filters as their primary source of drinking water and the intervention stoves as their primary cooking stove. However, some householders continued to drink untreated water and most continued to cook on traditional stoves. The intervention was associated with a 97.5% reduction in mean faecal indicator bacteria (Williams means 0.5 vs. 20.2 TTC/100 mL, p<0.001) and a median reduction of 48% of 24-h PM2.5 concentrations in the cooking area (pu200a=u200a0.005). Further studies to increase compliance should be undertaken to better inform large-scale interventions. Trial registration: Clinicaltrials.gov; NCT01882777; http://clinicaltrials.gov/ct2/results?term=NCT01882777&Search=Search

Maximizing the benefits of improved cookstoves: moving from acquisition to correct and consistent use.

The adoption of clean cooking technologies goes beyond mere product acquisition and requires attention to issues of cooking traditions, user engagement, gender dynamics, culture, and religion to effect correct and consistent use. The adoption of clean cooking technologies goes beyond mere product acquisition and requires attention to issues of cooking traditions, user engagement, gender dynamics, culture, and religion to effect correct and consistent use.

Quantitative stove use and ventilation guidance for behavior change strategies.

Achieving World Health Organization air quality targets and aspirational fuel savings targets through clean cooking solutions will require high usage rates of high-performing products and low usage rates of traditional stoves. Catalyzing this shift is challenging as fuel and stove use practices associated with new technologies generally differ from those used with traditional technologies. Accompanying this shift with ventilation improvements can help further reduce exposure to emissions of health damaging pollutants. Behavior change strategies will be central to these efforts to move users to new technologies and minimize exposure to emissions. In this article, the authors show how behavior change can be linked to quantitative guidance on stove usage, household ventilation rates, and performance. The guidance provided here can help behavior change efforts in the household energy sector set and achieve quantitative goals for usage and ventilation rates.

Nitrogen dioxide and ozone as factors in the availability of lead from lead-based paints.

Lead-based paint remains a pervasive problem in U.S. cities, and an increasing problem in the developing world where it is still manufactured and used. Little attention has focused on the factors that increase the release of lead pigment granules from painted surfaces. Nitrogen dioxide (NO(2)) and ozone (O(3)) from transportation emissions in urban environments have the potential to react with and remove polymeric binders in paint, making pigment granules more available for subsequent transfer to hands on contact, or deposition in housedust. Here we show that exposure to NO(2) and O(3) increased the lead in wipe samples of stainless steel surfaces painted with alkyd low gloss solvent lead-based paint by 296% +/- 101 (or 0.24 microg/cm(2)) and 37% +/- 21 (or 0.025 microg/cm(2)), respectively, with corresponding changes in surface morphology indicated by reflectometry and scanning electron microscopy. Lead release from unexposed low gloss acrylic household paints was 40 times greater than comparable solvent based paints. Given that lead-based paint is still manufactured and used in many urban areas of the developing world where O(3) concentrations currently exceed historic U.S. concentrations, the interaction of air pollution with lead painted indoor surfaces may pose greater exposure risks for lead poisoning in children than previously anticipated.

Factors Influencing the Acquisition and Correct and Consistent Use of the Top-Lit Updraft Cookstove in Uganda

This study looked at the effects of select behavior change interventions on the purchase and the correct and consistent use of a locally fabricated top-lit updraft (TLUD) stove in Uganda. Behavior change interventions included training of community sales agents and village health team volunteers on household air pollution and correct use, referral of interested community members to sales agents, community cooking demonstrations, information flyers, and direct sales of TLUDs and processed wood. Qualitative and quantitative research methods shaped interventions and were used to understand attitudes and practices related to TLUD stove acquisition and use. Results showed that TLUDs were appreciated because they use wood efficiently, cook quickly, reduce smoke, and produce charcoal. However, the substantial purchase price barrier, combined with the cost of processed wood, effectively eliminated the cost savings from its significant fuel efficiency. This made it difficult for the TLUD to be a meaningful part of most households’ cooking practices.

Quantifying the Contribution to Uncertainty in Mortality Attributed to Household, Ambient, and Joint Exposure to PM2.5 From Residential Solid Fuel Use

Abstract While there have been substantial efforts to quantify the health burden of exposure to PM2.5 from solid fuel use (SFU), the sensitivity of mortality estimates to uncertainties in input parameters has not been quantified. Moreover, previous studies separate mortality from household and ambient air pollution. In this study, we develop a new estimate of mortality attributable to SFU due to the joint exposure from household and ambient PM2.5 pollution and perform a variance‐based sensitivity analysis on mortality attributable to SFU. In the joint exposure calculation, we estimate 2.81 (95% confidence interval: 2.48–3.28) million premature deaths in 2015 attributed to PM2.5 from SFU, which is 580,000 (18%) fewer deaths than would be calculated by summing separate household and ambient mortality calculations. Regarding the sources of uncertainties in these estimates, in China, India, and Latin America, we find that 53–56% of the uncertainty in mortality attributable to SFU is due to uncertainty in the percent of the population using solid fuels and 42–50% from the concentration‐response function. In sub‐Saharan Africa, baseline mortality rate (72%) and the concentration‐response function (33%) dominate the uncertainty space. Conversely, the sum of the variance contributed by ambient and household PM2.5 exposure ranges between 15 and 38% across all regions (the percentages do not sum to 100% as some uncertainty is shared between parameters). Our findings suggest that future studies should focus on more precise quantification of solid fuel use and the concentration‐response relationship to PM2.5, as well as mortality rates in Africa.

The Firepower Sweep Test: A novel approach to cookstove laboratory testing

Emissions from solid-fuel cookstoves have been linked to indoor and outdoor air pollution, climate forcing, and human disease. Although task-based laboratory protocols, such as the Water Boiling Test (WBT), overestimate the ability of improved stoves to lower emissions, WBT emissions data are commonly used to benchmark cookstove performance, estimate indoor and outdoor air pollution concentrations, estimate impacts of stove intervention projects, and select stoves for large-scale control trials. Multiple-firepower testing has been proposed as an alternative to the WBT and is the basis for a new standardized protocol (ISO 19867-1:2018); however, data are needed to assess the value of this approach. In this work, we (a) developed a Firepower Sweep Test [FST], (b) compared emissions from the FST, WBT, and in-home cooking, and (c) quantified the relationship between firepower and emissions using correlation analysis and linear model selection. Twenty-three stove-fuel combinations were evaluated. The FST reproduced the range of PM2.5 and CO emissions observed in the field, including high emissions events not typically observed under the WBT. Firepower was modestly correlated with emissions, although the relationship varied between stove-fuel combinations. Our results justify incorporating multiple-firepower testing into laboratory-based protocols but demonstrate that firepower alone cannot explain the observed variability in cookstove emissions.

Fugitive Emissions and Health Implications of Plancha-Type Stoves

Plancha-type stoves have been widely disseminated in Mexico and Central America, but the contribution of fugitive emissions from these stoves to indoor air concentrations has been poorly quantified. In this study, fugitive emissions were measured for four plancha-type cookstoves most disseminated in Mexico (Patsari, ONIL, Ecostufa, and Mera-Mera). In controlled testing, fugitive emissions from plancha-type chimney stoves ( n = 15 for each stove) were on average 5 ± 3% for PM2.5 and 1 ± 1% for CO, much lower than defaults in WHO Guidelines (25 ± 10%). Using a Monte Carlo single zone model with locally measured parameters, average kitchen concentrations resulting from fugitive emissions were 15 ± 9 μg/m3 for PM2.5 and 0.06 ± 0.04 mg/m3 for CO. On the basis of these models, plancha-type stoves meet benchmarks for WHO Air Quality Guidelines (AQG) Interim Target I for PM2.5 and the 24 h AQG for CO, respectively, with on average 97% of homes meeting the guideline for PM2.5. Similarly, all four plancha-type stoves were ISO IWA Tier 4 for indoor emissions of CO and Tier 3 for indoor emissions of PM2.5. Three-dimensional computational fluid dynamics (CFD) analysis was used to estimate neighborhood pollution impacts of upstream chimney emissions. When chimney emissions were included as background concentrations combined with indoor contributions from fugitive emissions, plancha-type stoves would still meet the WHO AQG Annual Interim Target I for PM2.5 and the 24 h AQG for CO for the scenario modeled in this study.

Building a consumer market for ethanol-methanol cooking fuel in Lagos, Nigeria

A recently completed randomized controlled study in Nigeria that transitioned pregnant women from traditional fuels to ethanol in their cook stoves demonstrated improved pregnancy outcomes in mothers and children. We subsequently conducted a pilot study of 30 households in Lagos, Nigeria, to determine the acceptability of blended ethanol/methanol as cooking fuel and willingness to pay for the Clean Cook stove. A third of the pilot participants expressed a willingness to purchase the stove for the minimum price of 42 USD or more. Fuel sales data suggest sustained, but non-exclusive, use of the CleanCook stove. These results will influence the final design and implementation of a planned 2500 stove commercial pilot that is scheduled to start in Nigeria in August 2018.