Rufus Edwards

An assessment of programs to promote improved household stoves in China

In 2002, a team of US and Chinese researchers collaborated on an independent, multidisciplinary review of Chinas improved rural household stove programs that have been carried out since the 1980s. The objectives were to delineate and evaluate the methods used to promote improved stoves, to assess the development of commercial stove production and marketing organizations, and to measure the household impacts of the programs through surveys of health, stoves, and indoor air quality. The team found that China implemented broadly successful programs that delivered better stoves to a majority of households in targeted counties. That success was based on strong administrative, technical, and outreach competence and resources situated at the local level, motivated by sustained national-level attention. Despite overstated claims for penetration of improved stoves, mostbiomass stoves now in use have flues and other “improved” aspects, although field efficiencies are less than design efficiencies. However, most coal stoves, even those using improved fuel (briquettes), lack flues and cannot be considered improved. While in most areas “improved” stove technology became “conventional”, some areas remain significant exceptions and require intervention. Large roles for government oversight of quality control and support of R&D remain inadequately fulfilled. Most results of indoor air quality monitoring and health surveys were not clear-cut, in part because of the wide variety of fuel and stove combinations used by households. For nearly all household stove/fuel groupings, however, PM4 levels were higher than – and sometimes more than twice as high as – the national standard for indoor air (150 μg PM10/m3). If these results are typical, then a large fraction of Chinas rural population is now chronically exposed to levels of pollution far higher than those determined by the Chinese government to harm human health. Improved stoves in the surveyed households did result in reduced PM4 concentrations indoors for biomass fuel combinations. Coal use was associated with elevated levels of CO in exhaled breath, and improved biomass stoves with lower levels. Childhood asthma and adult respiratory disease were positively associated with coal use and negatively associated with improved stoves and good stove maintenance. The benefits of using improved biomass stoves can be outweighed by the use of portable coal stoves without flues. Evaluation of the programs provides important lessons for future initiatives in China and in other countries.

Indoor time-microenvironment-activity patterns in seven regions of Europe

Personal exposure to environmental substances is largely determined by time–microenvironment–activity patterns while moving across locations or microenvironments. Therefore, time–microenvironment–activity data are particularly useful in modeling exposure. We investigated determinants of workday time–microenvironment–activity patterns of the adult urban population in seven European cities. The EXPOLIS study assessed workday time–microenvironment–activity patterns among a total of 1427 subjects (age 19–60 years) in Helsinki (Finland), Athens (Greece), Basel (Switzerland), Grenoble (France), Milan (Italy), Prague (Czech Republic), and Oxford (UK). Subjects completed time–microenvironment–activity diaries during two working days. We present time spent indoors — at home, at work, and elsewhere, and time exposed to tobacco smoke indoors for all cities. The contribution of sociodemographic factors has been assessed using regression models. More than 90% of the variance in indoor time–microenvironment–activity patterns originated from differences between and within subjects rather than between cities. The most common factors that were associated with indoor time–microenvironment–activity patterns, with similar contributions in all cities, were the specific work status, employment status, whether the participants were living alone, and whether the participants had children at home. Gender and season were associated with indoor time–microenvironment–activity patterns as well but the effects were rather heterogeneous across the seven cities. Exposure to second-hand tobacco smoke differed substantially across these cities. The heterogeneity of these factors across cities may reflect city-specific characteristics but selection biases in the sampled local populations may also explain part of the findings. Determinants of time–microenvironment–activity patterns need to be taken into account in exposure assessment, epidemiological analyses, exposure simulations, as well as in the development of preventive strategies that focus on time–microenvironment–activity patterns that ultimately determine exposures.

VOC concentrations measured in personal samples and residential indoor, outdoor and workplace microenvironments in EXPOLIS-Helsinki, Finland

Thirty target volatile organic compounds (VOC) were analyzed in personal 48-h exposure samples and residential indoor, residential outdoor and workplace indoor microenvironment samples as a component of EXPOLIS-Helsinki, Finland. Geometric mean residential indoor concentrations were higher than geometric mean residential outdoor concentrations for all target compounds except hexane, which was detected in 40% of residential outdoor samples and 11% of residential indoor samples, respectively. Geometric mean residential indoor concentrations were significantly higher than personal exposure concentrations, which in turn were significantly higher than workplace concentrations for compounds that had strong residential indoor sources (d-limonene, alpha pinene, 3-carene, hexanal, 2-methyl-1-propanol and 1-butanol). 40% of participants in EXPOLIS-Helsinki reported personal exposure to environmental tobacco smoke (ETS). Participants in Helsinki that were exposed to ETS at any time during the 48-h sampling period had significantly higher personal exposures to benzene, toluene, styrene, m,p-xylene, o-xylene, ethylbenzene and trimethylbenzene. Geometric mean ETS-free workplace concentrations were higher than ETS-free personal exposure concentrations for styrene, hexane and cyclohexane. Geometric mean personal exposures of participants not exposed to ETS were approximately equivalent to time weighted ETS-free indoor and workplace concentrations, except for octanal and compounds associated with traffic, which showed higher geometric mean personal exposure concentrations than any microenvironment (o-xylene, ethylbenzene,benzene, undecane, nonane, decane, m,p-xylene, and trimethylbenzene). Considerable differences in personal exposure concentrations and residential levels of compounds with mainly indoor sources suggested differences in product types or the frequency of product use between Helsinki, Germany and the United States.

Performance testing for monitoring improved biomass stove interventions: experiences of the Household Energy and Health Project (1)

This paper describes the monitoring and evaluation of three improved cookstove dissemination projects implemented between 2004 and 2006 by non-governmental organizations (NGOs) in India and Mexico. The projects assessed stove performance using lab-based water boiling tests (WBTs), which yield a number of performance indicators including time to boil water, specific fuel consumption, and energy efficiency when the stove is operated at both high and low power output. They also conducted field-based kitchen performance tests (KPTs), which yield daily per capita fuel consumption in real cooking conditions. In addition, one NGO utilized a controlled cooking test, which combined elements of lab- and field-based tests. In all cases, improved cookstoves (ICSs) were compared to local traditional cookstoves (TCSs). The results of the WBTs were mixed. Although the improved stoves generally showed some improvement in efficiency for the low-power simmering phases, the stoves were less efficient than traditional stoves in high-power water-boiling phases. The results from the KPTs were much less ambiguous. Three ICS models were tested for fuel consumption during real household use. All ICSs showed statistically significant reductions (p < 0.05) in average daily per capita fuel use ranging from 19 to 67 %. We also explore the correlations between the outcomes in lab-based tests and field-based tests in order to understand the relationships between the two assessment methods. Only fuel consumption in the low-power phase of the WBT showed a strong correlation with fuel consumption in the field (r 2 = 0.83, p = 0.01). We discuss the implications of this association as well as the other outcomes and present some policy recommendations for monitoring and evaluation of large-scale stove interventions.

Personal child and mother carbon monoxide exposures and kitchen levels: methods and results from a randomized trial of woodfired chimney cookstoves in Guatemala (RESPIRE).

During the first randomized intervention trial (RESPIRE: Randomized Exposure Study of Pollution Indoors and Respiratory Effects) in air pollution epidemiology, we pioneered application of passive carbon monoxide (CO) diffusion tubes to measure long-term personal exposures to woodsmoke. Here we report on the protocols and validations of the method, trends in personal exposure for mothers and their young children, and the efficacy of the introduced improved chimney stove in reducing personal exposures and kitchen concentrations. Passive diffusion tubes originally developed for industrial hygiene applications were deployed on a quarterly basis to measure 48-hour integrated personal carbon monoxide exposures among 515 children 0-18 months of age and 532 mothers aged 15-55 years and area samples in a subsample of 77 kitchens, in households randomized into control and intervention groups. Instrument comparisons among types of passive diffusion tubes and against a continuous electrochemical CO monitor indicated that tubes responded nonlinearly to CO, and regression calibration was used to reduce this bias. Before stove introduction, the baseline arithmetic (geometric) mean 48-h child (n=270), mother (n=529) and kitchen (n=65) levels were, respectively, 3.4 (2.8), 3.4 (2.8) and 10.2 (8.4) p.p.m. The between-group analysis of the 3355 post-baseline measurements found CO levels to be significantly lower among the intervention group during the trial period: kitchen levels: −90%; mothers: −61%; and children: −52% in geometric means. No significant deterioration in stove effect was observed over the 18 months of surveillance. The reliability of these findings is strengthened by the large sample size made feasible by these unobtrusive and inexpensive tubes, measurement error reduction through instrument calibration, and a randomized, longitudinal study design. These results from the first randomized trial of improved household energy technology in a developing country and demonstrate that a simple chimney stove can substantially reduce chronic exposures to harmful indoor air pollutants among women and infants.

Impact of Patsari improved cookstoves on indoor air quality in Michoacán, Mexico

Little quantitative monitoring and evaluation of the impacts of improved stoves have been performed in Mexico. Grupo Interdisciplinario de Tecnologia Rural Apropiada (GIRA) has recently disseminated 4,000 improved Patsari cookstoves, most of them in the Purepecha region of Michoacan state, Mexico. In paired comparisons in a subset of kitchens in a single community before and after installation of an improved Patsari cookstove, 48-hour average kitchen concentrations of carbon monoxide (CO) and fine particulate matter (PM2.5) were reduced by 66 % (n = 32) and 67 % (n = 33), respectively. Kitchens that had more elevated concentrations during the baseline measurements demonstrated more dramatic reductions, as the overall variability was reduced when the improved stove was used. Thus, the Patsari stove provides an effective means of reducing kitchen air pollution and potential benefits of installing these stoves are considerable. Although requiring significant additional resources, the Household Energy and Health (HEH) Project catalyzed a much broader investigation into health, climate, environment and societal impacts of Patsari stoves, which has had a greater impact on public policy than the direct impact of the number of improved stoves installed in these communities.

Reduction in personal exposures to particulate matter and carbon monoxide as a result of the installation of a Patsari improved cook stove in Michoacan Mexico

UNLABELLED The impact of an improved wood burning stove (Patsari) in reducing personal exposures and indoor concentrations of particulate matter (PM(2.5)) and carbon monoxide (CO) was evaluated in 60 homes in a rural community of Michoacan, Mexico. Average PM(2.5) 24-h personal exposure was 0.29 mg/m(3) and mean 48-h kitchen concentration was 1.269 mg/m(3) for participating women using the traditional open fire (fogon). If these concentrations are typical of rural conditions in Mexico, a large fraction of the population is chronically exposed to levels of pollution far higher than ambient concentrations found by the Mexican government to be harmful to human health. Installation of an improved Patsari stove in these homes resulted in 74% reduction in median 48-h PM(2.5) concentrations in kitchens and 35% reduction in median 24-h PM(2.5) personal exposures. Corresponding reductions in CO were 77% and 78% for median 48-h kitchen concentrations and median 24-h personal exposures, respectively. The relationship between reductions in median kitchen concentrations and reductions in median personal exposures not only changed for different pollutants, but also differed between traditional and improved stove type, and by stove adoption category. If these reductions are typical, significant bias in the relationship between reductions in particle concentrations and reductions in health impacts may result, if reductions in kitchen concentrations are used as a proxy for personal exposure reductions when evaluating stove interventions. In addition, personal exposure reductions for CO may not reflect similar reductions for PM(2.5). This implies that PM(2.5) personal exposure measurements should be collected or indoor measurements should be combined with better time-activity estimates, which would more accurately reflect the contributions of indoor concentrations to personal exposures. PRACTICAL IMPLICATIONS Installation of improved cookstoves may result in significant reductions in indoor concentrations of carbon monoxide and fine particulate matter (PM(2.5)), with concurrent but lower reductions in personal exposures. Significant errors may result if reductions in kitchen concentrations are used as a proxy for personal exposure reductions when evaluating stove interventions in epidemiological investigations. Similarly, time microenvironment activity models in these rural homes do not provide robust estimates of individual exposures due to the large spatial heterogeneity in pollutant concentrations and the lack of resolution of time activity diaries to capture movement through these microenvironments.

The impact of improved wood-burning stoves on fine particulate matter concentrations in rural Mexican homes

To evaluate the impact of improved wood burning stoves on indoor air pollution, 53 homes in a rural town in Michoacán, Mexico, were selected from a health intervention study and monitored before and after receiving improved wood-burning stoves. Fine particulate matter — particles with aerodynamic diameter less than 2.5 μm (PM2.5) — concentrations were measured in the central plaza of the community and in three microenvironments in the home (next to the stove, in the kitchen away from the stove, and outdoor patio). Forty-eight hour mean PM2.5 concentrations in homes that burned wood in open fires were 693 μg/m3 (95% CI: 246–1338) near the stove, 658 μg/m3 (95% CI: 67–1448) in the kitchen away from the stove, and 94 μg/m3 (95% CI: 36–236) on the patio. Mean ambient 24-h concentrations in the main plaza of the community were 59 μg/m3 (95% CI: 29–92). Paired measurements before and after the installation of the Patsari improved wood-burning stove indicate a median 71% reduction in PM2.5 concentrations near the stove and 58% reductions in kitchen concentrations, whereas patio and main plaza concentrations remain unaffected. Only 44% of participants reported to use their Patsari stoves exclusively during the transition period. Even with the predominant mixed use of the Patsari stove with open fires, estimated daily average personal exposures to PM2.5 were reduced by 50%.

Impact of improved cookstoves on indoor air quality in the Bundelkhand region in India

Despite the reach of Indias National Program on Improved Chulhas, little quantitative monitoring and evaluation of improved stove projects in India has previously been undertaken by non-governmental organizations. Development Alternatives (DA) recently distributed 980 improved chimney cookstoves (Sukhad stoves) in the Bundelkhand region of India. In a subset of these households (n = 60), DA undertook a comprehensive assessment of the impact of the improved Sukhad stove on indoor air quality. Measurements of carbon monoxide (CO) and fine particulate matter (PM 2.5 ) were conducted for a 48-hour period in 60 rural kitchens in Bundelkhand before and after installation of the Sukhad stove. One year after the installation of the of the Sukhad, 48-hour average CO concentrations were reduced, on average, by 70% (p 2.5 concentrations were reduced, on average, by 44% (p

Impact of improved biomass cookstoves on indoor air quality near Pune, India

To reduce the impact of indoor air pollution and improve fuel efficiency, the Appropriate Rural Technology Institute (ARTI), in conjunction with ten non-governmental organizations, helped establish rural enterprises that subsequently distributed 30,000 improved cement cookstoves in Maharashtra, India, between August 2004 and December 2005. In a subset of these households (n = 110), ARTI undertook a comprehensive assessment of the impact of the improved Laxmi (vented) and Bhagyalaxmi (unvented) stoves on indoor air quality. Measurements of carbon monoxide (CO) and fine particulate matter (PM 2.5 ) were taken for a 48-hour period in kitchens before and after installation of improved stoves. One year after the installation of the improved stoves, the 48-hr mean CO concentration was reduced, on average, by 39% for the Laxmi and 38% for the Bhagyalaxmi. Similarly, the 48-hr mean PM 2.5 concentration was reduced, on average, by 24% for the Laxmi and 49% for the Bhagyalaxmi. Key challenges during the monitoring were: (1) motivating household members to purchase the improved cookstoves (ICSs); (2) ensuring that the households made the transition to using the ICSs; and (3) maintaining high standards of data quality as a field team. Despite the challenges, the importance of monitoring and evaluation remains critical in verifying the benefits of improved stove designs. Building on the lessons that we have learned, future efforts will focus on monitoring and evaluating fewer villages to concentrate resources, establishing a stronger rapport with study participants, and better understanding the dynamics of stove adoption in each home. Our hope is that this experience will aid other organizations in the design of their own ICS monitoring and evaluation programs.