Household Energy Solutions in Developing Countries

Bruce NG, Rehfuess EA and Smith KR,
Household Energy Solutions in Developing
In: Nriagu JO (ed.) Encyclopedia of
Environmental Health, v 3, pp. 6275 Burlington:
Elsevier, 2011.
Household Energy Solutions in Developing Countries
NG Bruce, University of Liverpool, Liverpool, UK
EA Rehfuess, World Health Organization, Geneva, Switzerland
KR Smith, School of Public Health, University of California, Berkeley, CA, USA
& 2011 Elsevier B.V. All rights reserved.
acute lower respiratory infection
air quality guideline
cost-benefit analysis
cost-effectiveness analysis
cost-effectiveness ratio
chronic obstructive pulmonary disease
Demographic and Health Survey
Deutsche Gesellschaft fu¨r Technische
Zusammenarbeit (German Federal Agency
for International Development)
International Energy Agency
particulate matter, usually defined by
aerodynamic diameter in microns, for
example, PM10 (10 microns in diameter),
or PM2.5 (2.5 microns in diameter)
World Health Organization
Indoor air pollution (IAP) from solid household fuel use
is associated with a substantial global health burden, and
addressing this is a public health priority. In considering
solutions, one of the most important factors influencing
options for change and methods of delivery is the close
relationship between reliance on traditional fuels and
poverty (Figure 1).
This relationship operates in both directions. On the
one hand, poor households do not have the financial
resources and income security required to switch to more
efficient, cleaner fuels and energy technologies. At the
same time, the consequences of using traditional fuels –
which include impacts on health, women’s time and
opportunities for income generation – add to the constraints on families attempting to escape from poverty.
For these reasons, poverty is a key underlying issue
in any consideration of household energy solution for
developing countries. However, since improving access to
cleaner and more efficient household energy will make
direct contributions to both health improvement and
poverty reduction, it is important not to rely on economic growth and other poverty reduction measures as
the primary means of improving energy choices for poor
households. This is similar to household interventions
for clean water and sanitation, which serve to assist poor
families’ health and their prospects for improving their
condition in other ways. Effective strategies for accelerating the transition to clean household energy are
required as a matter of urgency.
This article considers the range of interventions and
policies available to achieve this transition, and reviews
their effectiveness and efficiency, along with experience
from projects and programs over the past 30 years.
What Benefits Can Household Energy
Interventions Deliver?
A critical issue in considering appropriate household
energy solutions is to identify the potential benefits. Although reducing IAP is the priority, there is growing
recognition that other consequences of household energy
use in developing countries are also important. These are
summarized in Table 1, and lead to a range of objectives
that inform the design and promotion of household energy interventions (Box 1).
The extent to which all of these objectives are relevant
in any given setting will vary, but this represents a
starting point. As this article is concerned primarily
with health impacts, the following sections will focus on
reducing pollution and return to the other benefits in
discussion of economic analysis.
Fraction of traditional fuel use
R2 = 0.6239
600 1000
Per capita GNP, 1999 (US$)
Figure 1 The relationship between per capita GNP and fraction
of the population using traditional fuels. Source: Smith KR, Mehta
S, Feuz M (2004) Indoor air pollution from household use of solid
fuels. In: Ezzati M (ed.) Comparative Quantification of Health
Risks: Global and Regional Burden of Disease Attributable to
Selected Major Risk Factors. Geneva: World Health Organization.
Household Energy Solutions in Developing Countries
Table 1
The diverse impacts of household energy illustrate the wide range of potential benefits from interventions
Area of impact
Specific impacts
Exposure to high levels of indoor
air pollution (products of
incomplete combustion)
Available evidence strong for childhood ALRI, and COPD and lung
cancer (coal use) in adults. Tentative evidence for increased risk
of lung cancer with biomass, upper aerodigestive tract cancer,
TB, low birthweight, stillbirth, cataract, asthma, and
cardiovascular disease.
Young children suffer burns from falling into open fires, picking up
hot fuel. Cooks at risk of clothes igniting, especially in countries
such as India where long drapes worn. Scalds to children from
knocking over pots that are on stoves at floor level. Clothes,
bedding, and house fires from knocking over candles and simple
kerosene lamps, which are very common in the absence of
Where kerosene (paraffin) is used as a household fuel, this is
frequently stored in soft drink bottles, and poisoning of young
children who drink the fuel is common.
Most collection of fuel is carried out by women, and school-age
children are often involved. Although not well studied and
quantified, there is sufficient evidence that injuries (from falling
with heavy loads) and animal bites (snakes, etc.) are quite
common. Women may also have increased risk of uterine
prolapse. In some areas, particularly of political instability, women
may be at risk of physical threats, assault, and rape.
The use of fuel wood can place pressure on forest resources,
although the extent of this usually depends on other pressures
including timber requirements for building and land clearance for
agriculture. The use of dung for fuel diverts this from being used
to increase soil fertility.
The low combustion efficiency, around 10–20%, of most solid fuel
stoves in developing countries results in substantial global
warming emissions. These include methane, the warming effect
of which is more than 20 times that of CO2, and black carbon that
has an effect around 700 times that of CO2.b
Where households collect fuel, the time spent varies considerably
but is not infrequently (on average) 1–2 h per day, and can be
considerably more as fuel resources become scarce.
Inefficient stove combustion and design may result in more time
spent cooking.
Energy is important for income generation in a variety of ways,
including, for example, fuel for drying foods (e.g., fish) or
preparing cooked food to sell, and the provision of adequate
lighting to carry out handcrafts in homes with poor natural lighting
or in the evenings.
Inadequate lighting at home is a barrier to school children who have
homework, or other household members who wish to study
Since the role of women generally includes responsibility for
procuring household fuel and carrying out cooking, it is women
who bear most of the burden on health and other aspects of their
lives described here. Furthermore, women often have less control
of resources (including land use) and decision-making, which
means that they have little control over measures that could
improve these conditions. For this reason, many communitybased intervention programs often attempt to involve women in
the development process, and help them make decisions about
appropriate technology and other changes to the home and
kitchen, how these should be financed, and so forth.
Increased risk of burns and
scalds due to open nature of
fires, and location (often) on
Injuries and animal bites during
fuel collection
Local environmental impacts from
pressure on forest resources
and use of animal dung
Global environmental impacts
from CO2 and other products of
incomplete combustion
Use of time
Time spent collecting fuel
Time spent cooking
Household activities
Income generation
School work
Gender issues
Disproportionate impact on
The International Energy Agency (IEA) estimates that more than 1.5 billion people still do not have access to electricity for lighting.
The global warming emissions from inefficient stoves has led to initiatives to promote the dual benefits of interventions, namely (1) short-term health
and related benefits to households and (2) longer-term climate change benefits. This offers the potential for financial support from developed
countries through official and voluntary carbon offset programs.
Household Energy Solutions in Developing Countries
Box 1 Range of Objectives for Household Energy Interventions (See Text for Further Discussion)
Reduced levels of IAP and human exposure: the question of how much (and to what level) IAP exposure needs to be reduced is
considered in the section on ‘Impacts of interventions on health outcomes’.
Increased fuel efficiency, including both efficiency in combustion and efficiency of transfer of heat for cooking tasks and space
heating (where required).
Reduced time spent in collecting fuel and in using inefficient stoves, particularly involving the time of women and school-aged
Reduced stress on the local environment in respect of forest cover, erosion, and soil fertility.
Increased opportunities for income generation.
Contribution to an overall improvement in the quality of the home environment, in particular the working environment and
conditions for women.
Reduced global warming emissions, with potential for linking implementation of interventions to the Clean Development
What Reductions in IAP Are Required?
Studies from many developing countries have shown
that levels of IAP in homes using solid fuels are well in
excess of World Health Organization (WHO) air quality
guidelines (AQGs). These AQGs apply to both outdoor
and indoor environments, and should serve as the longerterm objective of policy to maximize risk reduction in all
populations, urban and rural, rich and poor.
In practice, however, it is proving very difficult to
achieve such low pollution levels (e.g., annual average
of 20 mg m3 PM10, particulate matter 10) in most
developing country homes, and will remain so for some
time for the following reasons: (1) it is not currently
possible to obtain very low emissions with low-cost solid
fuel stoves, (2) the International Energy Agency (IEA)
estimates that the absolute number of people depending
on biomass fuels will increase to 2.6 billion by 2030, and
(3) there are contributions to personal exposure from the
outdoor environment, which include vented household
solid fuel emissions. The question then is, how much
health benefit can be obtained from a partial reduction in
IAP levels and exposure, for example, a 50% reduction in
24 h kitchen PM10 from 500 to 250 mg m3?
Studies from Kenya and Guatemala have provided
information to help answer this question for child
pneumonia. More details are provided in the section
‘Impacts of interventions on health outcomes,’ but the
conclusion is that technologies currently available in
developing countries can deliver a useful reduction in
childhood pneumonia, even though post-intervention
pollutant concentrations still exceed WHO AQGs.
Approaches to Delivering Improved
Household Energy in Developing
Improving access of households to cleaner and more
efficient energy requires both interventions and enabling
policy. These two aspects will now be considered, and then
evidence on how effective these are in practice will be
Interventions for reducing IAP can be grouped under
three headings: those acting on the source of pollution,
those improving the living environment, and those
modifying user behaviors (Table 2).
Switching from wood, dung, or charcoal to more
efficient modern fuels, such as kerosene, LPG, biogas,
and ethanol, brings about the largest reductions in IAP. In
many poor rural communities, however, access to these
alternatives is limited and biomass remains the most
practical fuel. Here, improved stoves – provided they are
adequately designed, installed, and maintained – can also
reduce IAP considerably. Stove location, housing construction, and better ventilation are also partial remedies.
Changing behaviors can also contribute: drying fuel
wood improves combustion and lowers emissions, using
pot lids cuts cooking time, and exposure of young children can be reduced by keeping them away from polluted
kitchens (if this is safe). Such changes are unlikely to
reduce IAP as much as cleaner fuel or a well-functioning
chimney stove, but are important supporting measures.
Solar cookers offer zero emissions and a free, inexhaustible source of energy, and can be effective in
settings with high solar irradiance. Experience with solar
cookers has, however, been mixed. Although their use
is relatively widespread in Tibet and on the Altiplano
of South America, where virtually no other clean fuel
alternatives are available, user acceptability (e.g., ability
to prepare local dishes and concern about theft) and cost
have prevented adoption in many other places. Another
promising approach is advanced combustion stoves that
achieve low emissions even using raw biomass in the
form of wood or crop residues. For example, one such
technology, semi-gasifier stoves, emits levels of pollution
almost as low as for LPG when operating well. Although
extremely promising, most such stoves are sensitive
Household Energy Solutions in Developing Countries
Table 2
Interventions for reducing exposure to IAP
Source of pollution
Living environment
User behaviors
Improved cooking devices
Improved ventilation
Improved biomass stoves without flues
Hoods, fireplaces, and chimneys built
Improved stoves with flues attached
Windows, ventilation holes, for
Reduced exposure through operation of
Fuel drying
Use of pot lids to conserve heat
Good maintenance of stoves and
chimneys and other appliances
into the structure of the house
example, in roof, which may have
cowls to assist extraction
Alternative fuel–cooker combinations
Briquettes and pellets
Liquefied petroleum gas
Biogas, producer gas
Solar cookers (thermal)
Other low-smoke fuels
Kitchen design and placement of the
Kitchen separate from house reduces
exposure of family (less so for cook)
Stove at waist height to reduce direct
exposure of cook leaning over fire
Reductions by avoiding smoke
Keeping children away from smoke, for
example, in another room (if available
and safe to do so)
Reduced need for the fire
Insulated fireless cooker (haybox)
Efficient housing design and
Solar water heating
Source: Modified from Ballard-Tremeer G, and Mathee A (2000) Review of interventions to reduce the exposure of women and young children to
indoor air pollution in developing countries. In von Schirnding Y, et al. (2002) Addressing the impact of household energy and indoor air pollution on
the health of the poor: Implications for policy action and intervention measures. WHO/HDE/HID/02.9. Geneva: WHO.
to fuel quality, including size and moisture, and relatively
few studies have been done on their field performance
over time in rural households. One way to increase
performance reliability is to include a small electric
blower, which stabilizes the combustion and uses tiny
amounts of electricity, what could be called ‘hybrid’
stoves. A small rechargeable battery can be incorporated
to ensure functioning in areas of unreliable power supply.
Another approach is briquetting or pelletizing of biomass,
which greatly improves stove performance but requires
creating a new small industry in rural areas.
Enabling Policy
Poor households face many barriers to adoption of
interventions, and enabling policy is needed as much as
changes in technology, fuels, and behaviors. These barriers arise because energy and associated technologies
are commodities, and the people concerned are poor, and
many are very poor. The poorer the community, the
more complete and entrenched the reliance on traditional fuels and stoves. Furthermore, as with many other
aspects of environmental health, implementation differs
from health care since interventions and policy are directed at issues that include energy supply and markets,
environmental improvement, housing, education, agriculture, gender, and development. Thus, although major
benefits may accrue to the health system, action is taken
mainly through other sectors, resulting in a lack of clarity
about roles and funding.
The fuels and devices used for cooking, heating, and
lighting are products and services and as such are just one
of a number procured by households to meet everyday
needs and compete for the limited resources available.
For many, energy is obtained without monetary expenditure by collecting wood, twigs, dung, and crop
residues and using stoves made from earth or stones. For
others, varying amounts of their daily energy needs
together with stoves and other technologies are purchased in markets that are influenced by local, national,
and international factors – most notably in recent years,
the price of oil. This has increased the cost of two
important cleaner fuels, kerosene and LPG, forcing
people down the energy ladder onto greater reliance on
biomass. Although households collecting all of their fuel
are outside formal markets, experience is showing that
effective, sustainable interventions will require engagement with markets for energy supply and products.
Policy should therefore generate demand through a
number of routes, including by regulation (e.g., on
standards for stove manufacture, or air quality, where
possible), by raising awareness of the health and other
benefits among communities and professional groups,
and also by facilitating greater engagement of poor
Household Energy Solutions in Developing Countries
households in markets for products appropriate to their
needs, culture, and circumstances. Policy instruments
that can support this approach are summarized in
Table 3.
Effectiveness of Interventions
The assessment of intervention effectiveness requires
consideration not only whether the intervention delivers
on IAP reduction and other objectives identified earlier
in text, but also whether it is acceptable to users,
is maintained, and remains in everyday use. It is useful to
distinguish efficacy (what an intervention delivers in ideal
circumstances) from effectiveness (what it does in realistic
situations) and efficiency (whether it does so cost-effectively). Here, effectiveness and efficiency is the focus,
with the main emphasis on the reduction of IAP
and resulting health impacts. Two approaches can be
taken in respect of health improvements. The first assesses impact on ambient air pollution in and around the
home, and ideally also on personal exposure. The second
approach involves assessing the impact on specific health
Impact of Interventions on Household Pollution
and Personal Exposure
In East Africa, cheap improved ceramic (pottery) stoves
without flues, burning either wood or charcoal, are
popular and can reduce kitchen pollution by improving
combustion, although recent work suggests such reductions are small. Charcoal emits considerably less
particulate matter (PM), and stoves such as the Kenyan
Jiko have been shown to yield particulate levels in the
region of 10% of those from wood fires. Newer flueless
wood stoves with improved combustion such as the Rocket
are being introduced and evaluated in a number of
African countries.
Improved stoves with flues have been promoted extensively in several Asian countries, although many were
found to be in poor condition after a few years. Some
studies from India have shown variable and sometimes
modest or minimal reductions in pollution. For example,
Laxmi chimney stoves in homes located in Maharashtra,
India, resulted in a 24% reduction in PM2.5 and a 39%
reduction in CO, whereas a sukhad chimney stove in the
Bundelkhand region of India reduced kitchen concentrations of PM2.5 and CO by 44% and 70%, respectively.
Studies from Nepal have shown reductions of approximately two-thirds, although high baseline levels mean
that homes with stoves still recorded total PM values of
1000–3000 mg m3 during cooking.
Similar experience with flued stoves has been reported from Latin America. Plancha stoves in Guatemala
(made of cement blocks, with a metal plate and flue) can
reduce PM by 60–70%, and by as much as 90% when
well maintained. Typical 24 h PM levels (PM10, PM3.5,
and PM2.5 have been reported) with open fires of 1000–
2000 mg m3 have been reduced to 300–500 mg m3, and
in some cases less than 100 mg m3. A Mexican intervention study assessing the patsari flued stove in
Michoaca´n state found a 67% reduction in PM2.5 and a
66% reduction in CO.
IAP reductions studied in three provinces of China
found 24 h kitchen PM4 of 268 mg m3 for all traditional
stove types and 152 mg m3 for all improved stove types.
Although a significant reduction, most homes were
still above the Chinese national IAP air quality standard
of 150 mg m3 PM10. Evaluation was complicated by
multiplicity of fuel types in regular use, changes within
and between seasons, and multiple stove type use (improved and traditional) for various purposes.
Recent work developing hoods with flues for highly
polluted Kenyan Maasai homes reported reductions in
24 h mean PM3.5 of 75% from more than 4300 mg m3 to
approximately 1000 mg m3. Households may also opt for
combinations of changes: in west Kenya, hood and flues
used with ceramic stoves (for better combustion), hayboxes (insulated chambers that slow-cook hot food without fuel), and improved ventilation reduced kitchen levels
of CO (used as a proxy for PM) by approximately 70%.
Where studied, personal exposure has been found to
reduce proportionately less than area pollution. Thus, in
the Kenyan Maasai study, a 75% reduction in 24 h mean
kitchen PM3.5 and CO was associated with a 35% reduction in women’s mean 24 h CO exposure. Similar
proportionate reductions were found for women and
children using wood stoves in Guatemala. A study of
personal particulate exposure in Guatemalan children
o15 months of age reported mean 10 to 12 h PM2.5 levels
of 279 mg m3 for open fires and 170 mg m3 for plancha
stoves, a 40% difference.
Impact of Cleaner Fuels
Kerosene and LPG can deliver much lower pollution,
although for practical and cost reasons may not fully
substitute for solid fuel. For example, a study in rural
Guatemala comparing LPG with open fires and plancha
chimney stoves found that LPG-using households typically also used an open fire for space heating and cooking
with large pots. Consequently, the plancha homes had the
lowest pollution. Other studies from India have shown
that kerosene and LPG users had much lower kitchen
pollution, reflecting different cooking and space-heating
requirements. In rural Tamil Nadu, 2 h (meal time)
kitchen respirable PM (PMresp) levels of 76 mg m3
(kerosene) and 101 mg m3 (LPG) contrasted with 1500–
2000 mg m3 for wood and animal dung. Personal (cook)
Household Energy Solutions in Developing Countries
Table 3
Policy instruments for promoting implementation of effective household energy interventions
Policy instruments
1. Information,
education, and
Learning about household energy, health, and development integrated in
school curricula, particularly in countries where these topics are a priority for
health and economic development.
Local and national radio, television, and newspapers can be used to raise
awareness and disseminate information on technologies and opportunities
to support implementation, such as promotions and microcredit. These
media can be directed at a range of audiences, including decision makers,
professionals, and the public where radio is widely used.
Opportunities such as adult literacy programs can be used to raise awareness
and share experience of interventions, and innovative methods used, for
example, theatre.
Raising awareness about the impacts of solid fuels and IAP on health and
development is required for all sectors and professional groups with a part to
play. This includes identification of their roles, joint working, and the steps
each group can take to contribute effectively.
Reduced tax on fuels and appliances may promote development of distribution
networks and uptake, and can be seen as efficient if there is evidence of
health, education, and economic benefits.
General (e.g., national) subsidy on fuels such as kerosene has been used in an
effort to promote use by poor households. Subsidies have been found to be
inefficient instruments, however, often benefiting the better-off rather than
the poor. Time-limited subsidy on specific products (e.g., clean fuel
appliances and connection to grid) may be a useful method for promoting
initial uptake, generating demand, and thereby providing market conditions
for lower prices and more consistent quality. Climate change co-benefits can
provide a source of funding through formal or voluntary carbon offset
Although some developing countries have AQS for urban air, only China
currently has a standard for indoor air quality (150 mg m3 PM10). Routine air
pollution monitoring and enforcement of AQGs for homes is not practical in
most settings, but standards based on information about fuel and stove type
(obtained through surveys such as the DHS, Demographic and Health
Survey) can be used as an indicator of disease risk.
These can be applied to safety (prevention of burns, gas leaks, and
explosions), venting of emissions, and fuel efficiency. Although such
standards may be difficult to enforce in an informal economy, these could
become valuable with mass production and a greater involvement of the
private sector.
Large-scale public provision of appliances, such as improved stoves or clean
fuel appliances, has generally been found to be unsuitable. Some form of
targeted provision or partial subsidy where households have made informed
choices and commit to cost sharing may be useful to stimulate demand and
act in favor of equity.
Experience has shown that credit is most likely to be made available, and
adopted, for energy applications that contribute directly to productive,
income-generating activities (such as food processing for sale). Meeting
everyday cooking and space-heating needs is seen as a lower priority. Good
opportunities may exist where biomass fuel is purchased and where cost
saving combines with other valued benefits, such as increased prestige and
cleaner kitchens. Support for such schemes, mainly in the form of raising
awareness, skills training in managing funds, and seed funding (the main
source of funds being from users), may be cost-effective.
Surveys of fuel and appliance use, knowledge of risks to health, willingness to
pay for interventions, knowledge of and confidence in credit schemes, and
so forth are important for planning interventions.
Evaluation of interventions should be conducted in a range of settings, where
possible using harmonized methods that allow local flexibility but permit
comparison with other types of interventions and other locations.
Stronger and better-quantified evidence of the effects on health of reducing
IAP, which includes exposure measurement, is required for key outcomes
such as ALRI, but also for other health outcomes for which evidence is
currently tentative.
Capacity for carrying out a wide range of research, from national and local
surveys, monitoring, and evaluation of interventions through to more
complex health studies, requires strengthening in those countries where the
problems associated with household energy and IAP are most pressing.
Community education
Professional education
2. Taxes and
Tax on fuels and appliances
Subsidy on fuels and appliances
3. Regulation and
Air quality standards (AQS)
Design standards for appliances
4. Direct
Public program provision of
Funding of finance schemes
5. Research and
Development and evaluation of
Studies of health impacts
Research capacity development
Household Energy Solutions in Developing Countries
24 h exposure to PMresp was 132 mg m3 with kerosene
and 1300–1500 mg m3 for wood and dung.
For most developing country homes, electricity – even
if it were available – would be too expensive to use as a
cooking or heating fuel. South Africa is one of the few
countries with a large biomass and coal-using populations that has invested in rural electrification sufficient
to support cooking. A study comparing nonelectrified and
electrified villages in the North West province found 3.6
years after grid connection that 44% of electrified homes
had never used an electric cooker. Only 27% of electrified homes cooked primarily with electricity, the remainder using a mix of electricity, kerosene, and solid
fuels. Despite mixed fuel use, households cooking with
electricity had significantly lower 24 h mean PMresp and
CO levels and significantly lower mean 24 h CO exposure for children aged o18 months.
Impacts of Interventions on Health Outcomes
Few intervention-based studies of impact on the most
important health outcomes (child pneumonia, COPD,
and lung cancer) have been published. For child pneumonia, two studies are of particular interest. The first
was conducted in rural Kenya and, although an observational design, provides information on the relationship
between child acute lower respiratory infection (ALRI)
and a range of exposure associated with the use of
traditional wood stoves, improved stoves, and charcoal.
Some 93 infants living in 55 households were studied,
and personal exposure and ALRI incidence were assessed. ALRI incidence increased at a higher rate for
PM10 exposure levels below 2000 mg m3 than for levels
above 2000 mg m3, suggesting that the exposure–
response relationship is not linear but levels off at concentrations of approximately 2000 mg m3. The small
numbers and high incidence of ALRI indicate that confirmation of these findings is required.
The second is currently the only completed randomized-controlled trial. A total of 534 homes in rural
Guatemala either were randomized to receive an improved plancha chimney stove or continued to cook on an
open fire. Child exposure was assessed using CO, previously shown to be an adequate proxy for PM in this
setting. Preliminary results (reported in conference
abstracts) show that the plancha reduced kitchen pollution
by approximately 90% and child CO exposure by approximately 50%. ALRI incidence among children o18
months was determined through a combination of weekly
home visits by fieldworkers and physician examination.
The plancha resulted in a modest reduction in pneumonia
incidence (whether assessed by fieldworker or physician)
of approximately 10–20%, with larger reductions for
more severe cases of approximately 30% with hypoxemia
(low oxygen saturation).
For chronic obstructive pulmonary disease (COPD)
and lung cancer, two cohort studies have reported the
impact on these outcomes following introduction of improved stoves as part of the Chinese National Improved
Stove Programme. For lung cancer, the adjusted hazard
ratio for men using improved coal stoves compared
with traditional open coal fires was 0.59 (95% CI: 0.49–
0.71), and was 0.54 (95% CI: 0.44–0.65) for women. For
COPD, in a similar type of study, use of improved stoves
was associated with hazard ratios of 0.58 (95% CI: 0.49–
0.70) in men and 0.75 (95% CI: 0.62–0.92) in women.
The reduction in risk became unequivocal approximately
10 years after stove improvement.
Economic Evaluation of Household
Energy Interventions
Economic analysis is playing an increasingly important
role in decision-making for health. This article will first
look at cost-effectiveness analysis (CEA), which identifies
how much requires to be spent on an intervention to
obtain a given unit of health gain. The second approach
is cost–benefit analysis (CBA), which determines the
monetary value of all intervention costs and benefits, and
hence whether the investment in the intervention yields
a net gain in economic terms. Because of the capacity of
CBA to take into account a wide range of benefits, this
method is usually considered more appropriate for economic evaluation of household energy interventions, and
more emphasis is given to CBA here.
Cost-Effectiveness Analysis of Interventions at
Regional Level
The analysis reported in this article is based on work
by Mehta and Shahpar. This analysis examined both
improved stove and clean fuel options, and combinations,
with varying coverage:
access to improved stoves (stoves with flues), with 50
• and
95% coverage
to cleaner fuels (LPG or kerosene), with 50 and
• 95% coverage
part of the population with access to cleaner fuels
• (50%)
and part with improved stoves (45%)
Intervention costs included program costs, fixed costs
(including stoves), and recurrent fuel costs. Savings from
averted health-care costs were not included since many
of these cases currently go untreated. Health impacts
were estimated through the lowered risks associated with
reduced IAP exposure, based on a previous meta-analysis. It was assumed that cleaner fuels remove exposure
completely, whereas improved stoves reduce exposure
and associated health effects by 75% (from the discussion
in the section ‘Effectiveness of interventions’, this should
Household Energy Solutions in Developing Countries
be considered optimistic). Health outcomes included
were ALRI and COPD, as these were responsible for
nearly all of the 1.6 million deaths attributable to IAP.
Future costs and health impacts were discounted at
3%, and the implementation period was 10 years. Results
were expressed, for the five intervention scenarios with
differing coverage, by WHO region, as cost-effectiveness
ratios (CERs) in international dollars per healthy year
gained (Table 4).
Cleaner fuels yielded the greatest gains in healthy
years for all regions (not shown), but improved stoves
also had a significant impact, with the largest total
population health gains in sub-Saharan Africa and South
Asia for all types of interventions, and in East Asia and
Pacific (mainly China) for cleaner fuels. CERs in the two
regions with the largest attributable burdens of disease
(Africa and South East Asia) were most favorable for
improved stoves, although in both regions kerosene was
not far behind. In East Asia and Pacific, kerosene was
most cost-effective, followed by improved stove/clean
fuel combinations, and then LPG. Although these costeffectiveness estimates vary considerably across regions,
they do provide evidence that household energy interventions can be cost-effective. This is despite this CEA
being restricted to direct health benefits and only outcomes with current strong evidence of risk. Inclusion of
other health impacts of IAP and through other mechanisms (e.g., burns) can be expected to improve CERs.
Cost–Benefit Analysis
The WHO has recently published guidance on carrying
out CBA for household energy interventions, and applied
this to interventions at WHO regional level. The approach used and key results from the regional study,
together with three community case studies using similar
methods, are now reported.
In CBA, all main benefits are expressed in a common
unit of monetary value. The assessment of costs has much
in common with CEA. The key difference lies in the
impacts included as benefits and the methods for valuing
Cost–Benefit Analysis at Global and Regional
In the WHO study, costs and benefits were modeled
under eight different intervention scenarios, covering
three specific interventions: LPG, biofuel (ethanol), and a
chimneyless stove based on the Rocket design. As in the
CEA discussed earlier in text, cleaner fuels were assumed
to remove exposure and attributable health impacts
completely. A more conservative assumption was employed for the impact of improved stoves, where a reduction of 35% (and lower and upper values of 10 and
60% in sensitivity analysis) in personal exposure was
used as a proxy for likely reductions in health outcomes.
Two levels of population coverage were assumed, to reduce the population not served in 2005 by 50% or 100%
by 2015. The 50% scenarios were further subdivided
into one where all users of traditional fuels are targeted
equally and a pro-poor alternative that first targets those
with the most polluting and least efficient solid fuels in
the following order: dung and agricultural residues,
firewood, coal, and charcoal. The intervention period was
10 years, with future costs and impacts discounted at 3%.
The costs and benefits included in the analysis are
summarized in Table 5.
Results are shown initially as net present values
(NPV) for three of the intervention scenarios, by WHO
Table 4 Cost-effectiveness ratios for household energy interventions, expressed as the costs in international dollars ($1) per healthy
year (HY) gained, by intervention scenarios for selected WHO epidemiological subregions, 2002
6 270
11 050
14 050
7 500
24 200
1 000
2 000
2 410
1 180
16 200
11 020
17 740
15 120
7 350
1 410
The Americas
South and South
East Asia
Western Pacific
LPG and improved
Kerosene and
improved stoves
5 880
3 750
6 440
16 330
6 770
1 530
8 080
3 120
1 800
3 010
2 450
7 800
1 180
9 780
19 870
8 970
4 500
9 510
1 950
1 380
32 240
4 280
1 570
1 040
See web link for the explanation of regions – included in ESD article, which is the source for this table (
Note: Where a CER result is not shown, the region is already at or above the specified level of coverage for the intervention.
Household Energy Solutions in Developing Countries
Table 5
WHO cost–benefit analysis study: Overview of costs and impacts, and time horizon of modeled impacts
Immediate cost or impact
Delayed cost or impacta
Intervention costs
Investment costs, such as stove purchase
cost and cost of house alterations
Recurrent costs, such as fuel costs and
program costs
Acute lower respiratory infection (ALRI)
Not relevant
Health benefits and savings on
health-care costs
Chronic obstructive pulmonary
disease (COPD); lung cancer
Productivity gains due to reduced
Related to ALRI
Productivity gains due to reduced
Time savings
Environmental benefits
Not relevant
Related to COPD and lung cancer
among women and men above 30
years of age
Related to ALRI for children
Fuel collection time and cooking time
Local and global environmental benefits
Not relevant
Not relevant
Future costs and impacts are discounted at 3% rate per year.
Table 6
Net present values (average annual value: millions US$) for three intervention scenarios at 50% coverage
Scenario I
Scenario II
Scenario III
(LPG pro-poor)
(Improved stove)
The Americas
South and South
East Asia
Western Pacific
World (non-A)
World total (non-A)
2 440
2 660
1 060
2 240
4 570
4 410
1 590
1 740
2 480
1 070
2 120
6 160
4 580
1 630
3 000
4 580
13 030
2 010
4 940
2 180
4 260
7 920
2 880
2 510
3 640
3 110
3 960
1 690
2 260
2 150
3 850
1 830
4 040
23 230
49 460
57 290
97 430
3 050
6 530
29 970
10 340
56 610
105 540
138 920
4 210
4 850
33 350
1 620
43 510
54 050
77 490a
This figure and the two others in this row are total value of urban and rural areas across the world.
epidemiological subregion, in Table 6. The NPV is
the estimated total annual economic surplus – this is
calculated by subtracting net present (discounted) costs
from net present (discounted) economic benefits. Almost
all cells in the table show positive NPVs, and most are
substantial. The largest NPVs are seen overall for improved stoves and for all three scenarios in urban settings
in the western Pacific subregion.
Benefit–cost ratios for the same three intervention
scenarios are shown in Table 7. The majority either are
greater than 1 (signifying the value of benefits exceeds
costs) or have negative values that result from intervention
cost savings exceeding the intervention costs, for example,
where fuel costs are reduced through greater efficiency.
A striking conclusion is the dominance of time
savings, although averted child and adult deaths were
also important. This CBA shows that investments in
household energy and health interventions can be highly
cost beneficial and in some cases cost saving. Under the
model assumptions, improved stoves led to the greatest
overall benefit to society as reflected in the NPV
(Table 6). This holds particularly true in urban settings
where the majority of the population already pays for
fuel. This finding is important in view of IEA projections
to 2030, which indicate that biomass will remain the
principal household fuel for the poor in South Asia
and sub-Saharan Africa and that actual numbers of users
will increase.
Household Energy Solutions in Developing Countries
Table 7
Benefit–cost ratios for three intervention scenarios at 50% coverage (US$ return per US$1 invested)
The Americas
Eastern Mediterranean
South and South East Asia
Western Pacific
World (non-A)
World total (non-A)
Scenario I
Scenario II
Scenario III
(LPG pro-poor)
(Improved stove)
This figure and the two others in this row are total value of urban and rural areas across the world.
Note: Neg, a negative benefit–cost ratio means that intervention cost savings exceed intervention costs.
Community-Based CBA Studies
The first study examined costs and benefits for 190 000
households using Rocket wood stoves and improved
charcoal stoves, promoted by GTZ in Uganda. Benefits
were similar to those described by WHO, and included
fuel saved, time saved collecting fuel and cooking, savings of time (illness) and costs to households and the
public health system, forestry, soil fertility, and greenhouse gases (CO2 and methane). Health benefits were
based on symptoms of respiratory and eye disease
and burns combined with nonempirical estimates of
reductions in health-care costs and time lost due to illness, but excluded mortality. Future costs and benefits
were discounted at 10% and the intervention period was
10 years. The overall program NPV was 57 million euro,
with a benefit–cost ratio of 25. Consistent with the WHO
study, benefits were dominated by fuel saving (including
time collecting fuel) at 51.9%, with time saved cooking
providing 14.3% and health benefits 7.4%.
The second community study was based on smallerscale community interventions carried out by Practical
Action (an international NGO) in highland Nepal
(addition of a LPG, hood and flue, and improved
stove with grate and wall insulation), Kassala in Sudan
(facilitated access to financing for LPG fuel and
stoves), and periurban communities around Kisumu,
Kenya (improved wood stoves, LPG, hoods and flues,
hayboxes, and improved ventilation). CBA was undertaken from a household perspective, drawing on WHO
guidelines. A 10% discount rate was used with a 10-year
intervention period. Results showed net economic benefit
in all countries, with average household NPVs (in
UK pounds) of 19, 634, and 149 for Nepal, Kenya, and
Sudan, respectively. Again, time and fuel costs were
the main contributors, although for Nepal fuel cost
savings were not relevant as all fuel was collected from
the forest.
The third study reports on a CBA of biogas carried
out by Winrock International for all of sub-Saharan
Africa as well as country-level analyses for Uganda,
Rwanda, and Ethiopia. The proposed interventions would
deliver integrated household biogas, latrine, and hygiene
facilities, and include a subsidy of approximately 30% of
the biogas unit cost. The analysis utilized data from
country-level feasibility studies, other secondary sources,
and limited primary data collection. Both household
and societal perspectives were used, the latter including
the value of time savings associated with fuel wood
collection, cooking, access to a latrine, a range of healthrelated benefits, and environmental benefits due to
reduction in greenhouse gas emissions and deforestation.
Benefit–cost ratio estimates were favorable, ranging from
1.2 to 1.3 for the household and from 4.5 to 6.8 for the
societal perspective.
Experience with the Implementation of
Household Energy Programs
The past 20–30 years have seen many, diverse programs
on household energy, from small and medium-scale
NGO and community-led initiatives to ambitious national programs, the largest of which achieved installation
of perhaps 200 million improved stoves in rural China.
It is important to note, however, that none of these
large programs in the past were designed specifically to
achieve low pollution exposures. Experience with a
Household Energy Solutions in Developing Countries
number of smaller-scale initiatives has also been reported
recently, some of which do focus on air pollution, and
several larger initiatives focusing on air pollution are now
underway (see the section ‘Relevant Websites’ for links to
current programs). Evaluation efforts are currently being
promoted and more reports should be available in the
next few years.
Among the large-scale initiatives, evaluations are
available and summarized here for the Indian National
Programme of Improved Cook Stoves (NPIC), the
Chinese National Improved Stoves Program, and LPG
The NPIC was established in 1983 with goals of conserving fuel, reducing smoke emissions and improving
health, reducing deforestation, limiting the drudgery of
women and children, and reducing cooking time and
improving employment opportunities for the rural poor.
Although the Ministry of Non-Conventional Energy
Sources was responsible for planning, setting targets, and
approving stove designs, state-level agencies relayed this
information to local government agencies or NGOs. A
technical backup unit (TBU) in each state trained rural
women or unemployed youths to become self-employed
workers to construct and install stoves. Many also conducted laboratory research to develop and test stoves.
Between 1983 and 2000, the program distributed more
than 33 million improved stoves, but despite extensive
efforts these now account for less than 7% of all stoves.
Among those that have been adopted, poor quality and
lack of maintenance have resulted in a lifespan of two
years at most and typically much less. Evaluation identified several problems:
Most states placed inadequate emphasis on com• mercialization,
now seen as crucial for effective and
sustainable uptake.
There was insufficient interaction with users, selfemployed workers, and NGOs, so that designs did
not meet household needs and there was very poor
acceptance of user training.
Quality control, monitoring, and evaluation for installation and maintenance of the stove and its appropriate use were lacking.
Most stoves used inexpensive materials with low
durability, leading to poor performance and short
High levels of subsidy (approximately 50% of stove
cost) were found to reduce household motivation to
use and maintain the stove.
There were some more successfully managed locations
that focused on technical assistance, research and development, marketing, and information dissemination.
Recently, the government of India decentralized the
program and transferred all implementation responsibility to state level. Since 2000, the NPIC promotes
only durable cement stoves with chimneys that have a
minimum lifespan of five years. The introduction of these
stoves will make adhesion to technical specifications and
quality control easier.
Implementation of the Chinese national program differed substantially from that of India, but operated over
the same period. Although rural Chinese populations are
poor, they do have greater effective purchasing power
than in many developing countries, allowing the majority
of consumers to purchase stoves at close to full cost.
Among the key features of the Chinese program reported
to have contributed to its success are decentralization
of administration, a commercialization strategy that
provided subsidies to rural energy enterprise development, and quality control through the central production
of critical components (such as combustion chamber
parts) and engaging local technical institutions in modifying national stove designs to local needs. National-level
stove competitions generated public and media interest, a
bidding process among counties for contracts allowing
the best-placed counties to proceed first; financial payments were provided to counties only after completion of
an independent review of their achievements. No large
flows of funds came from the center as the major financial
contributions were provided by local governments. The
Chinese program shifted norms: most biomass stoves now
available on the market have flues and other technical
features that classify them as improved.
In 2002, an independent study was undertaken to
evaluate (1) implementation methods used to promote
improved stoves, (2) commercial stove production and
marketing organizations that were created, and (3) impacts of the program on households, including health,
stove performance, socioeconomic factors, and monitoring of indoor air quality. The first two objectives were
assessed through a facility survey of 108 institutions at
all levels. The third objective was assessed through a
household survey of nearly 4000 households in Zhejiang,
Hubei, and Shaanxi provinces. Overall, several important
conclusions emerged. First, the impact of an improved
stove program on IAP and health may be limited in
settings where a wide range of combinations of different
fuel and stove types are used. Second, given the importance of space heating, making available an improved
biomass stove for cooking may not be a sufficient strategy
to reduce IAP: there is a need to promote improved
coal stoves that are increasingly common among rural
Chinese households. Third, even among households
using improved stoves (as noted in the section
Household Energy Solutions in Developing Countries
Box 2 Key Lessons Learned in the Promotion of New Markets for LPG in Developing Countries
LPG can be affordable outside of urban areas, where wood fuel is currently purchased. However, ‘‘for many consumers who do
not participate in the monetized economy, it will be premature to promote LPG markets.’’
One-time subsidies on appliances could be a good use of government (or other) resources.
Microcredit initiatives should emphasize the cost saving and productive potential, and seek to package both the gas (and
appliances) and the financing.
Concerns about safe handling, cylinder refilling, and transportation can be serious barriers to market expansion. These need to
be addressed through awareness raising among consumers and through strengthened regulatory environments.
Appliances for a range of end uses required by consumer needs must be available.
Government leadership is essential, backed up by policy that sets the basic parameters for successful market expansion, and
avoids conflict between, for example, subsidies on competing fuels that undermine efforts to promote LPG markets.
Specific initiatives, such as integrated energy centers (as in Morocco, South Africa), offer an effective means of developing
markets in rural areas.
Source: Based on McDade S (2004) Fueling development: The role of LPG in poverty reduction and growth. Energy for Sustainable
Development 8: 74–81.
‘Effectiveness of interventions’), PM4 and CO levels were
still found to exceed Chinese national indoor air standards (and were substantially higher than WHO AQGs).
Overall, this study showed that, in general, the improved
stoves were reducing IAP concentrations, but the use of
fuels and stoves was complex, and the actual levels of IAP
and reductions were quite variable, and consequently it
has not been easy to report a single figure (e.g., % reduction in PM) on the impact of the stoves.
Promotion of LPG
Experience in the promotion of LPG has also been reported, for example, from the Indian Deepam Scheme
and from the LPG Rural Energy Challenge. This latter
initiative, developed by UNDP and the World LPG
Association in 2002, is promoting the development of
new, viable markets for LPG in developing countries.
Key elements include the development of partnerships
in countries; regulatory environments that facilitate LPG
business development and product delivery; the reduction in barriers, for example, the introduction of
smaller (more affordable) gas bottles; and greater government and consumer awareness of costs and benefits.
Key lessons emerging from experience with the promotion of LPG markets are shown in Box 2.
Conclusions, and Research and
Development Agenda
Experience shows that household energy interventions,
in particular improved solid fuel stoves and cleaner fuels,
can deliver substantial IAP reductions although there are
important cautions. Large (or indeed any) reductions in
IAP should not be assumed, and furthermore, large reductions have been more difficult to achieve with solid
fuel interventions than with cleaner fuels. Even wellfunctioning improved stoves show postintervention levels
well in excess of WHO AQGs. Personal exposure is
generally not reduced proportionately as much as ambient pollution for any given intervention.
Although intervention-based evidence of impact on
health outcomes is still limited, there are indications that
the degree of exposure reduction achieved with wellfunctioning improved stoves can result in important reductions in incidence of child pneumonia, COPD, and
(where coal is used) lung cancer.
Economic analyses have shown that interventions can
be cost-effective. CBA studies have reported favorable
results, despite variations in settings, interventions, data
sources, and assumptions. Improved stoves have yielded
the most favorable economic results thus far. Time and
fuel savings were most important, compared to health,
even more so where averted mortality was not included
among the benefits. The findings strengthen the case for
interventions and for promoting awareness of the time
and fuel savings in addition to health benefits.
Experience from intervention programs has identified
a number of key pointers for success, including generation of demand, attention to the needs of users, local
commercialization and targeted financial assistance and
credit, careful engineering with robust materials, and
evaluation with associated feedback. Local initiatives will
usually have little impact unless there is national policy
that encourages the coordinated contributions of a range
of actors, including government (energy, health, housing,
and other ministries), business, NGOs, and community
Given that solid fuels are expected to be the main
household cooking energy source for more than 3 billion
people up to and beyond 2030, research is needed on
improving combustion efficiency (to reduce emissions
and save fuel), heat transfer, and ventilation of stoves.
For example, technology such as biomass gasification
and pelletization may have considerable potential, but
development and evaluation for wider use are still
Household Energy Solutions in Developing Countries
required. Just as with outdoor air pollution sources,
chimneys are not the long-term answer, but rather ways
to greatly reduce emissions at the source. At present, it
seems low-combustion stoves, such as the hybrid stoves,
show much promise, although more experience is needed. The research agenda for clean fuel is concerned
mainly with policy on how access can be rapidly and
substantially improved for poor households. In addition,
innovations in clean fuels such as biogas, ethanol, and
plant oils also need development and evaluation.
An exciting potential for co-benefits for both health
and climate protection is being explored in a number of
stove projects around the world. By taking advantage of
either official or voluntary carbon offset programs, resources from developed countries are being tapped for
this purpose. This could potentially provide substantial
resources for research and dissemination on advanced
household energy technologies with both low greenhouse
and low health-damaging emissions.
The key priorities for implementation in respect of
health outcome research are to extend the interventionbased evidence on health impacts required to strengthen
advocacy efforts, together with further description of the
exposure–response relationship for childhood pneumonia
to define medium and longer-term targets for exposure
reduction. This should draw on new data from a variety of
settings and span a wider range of exposure than is currently available. Exposure–response data for other health
outcomes is desirable, but has lower priority.
Economic evaluation is at an early stage, and there is a
need for more empirical evidence on costs and the full
range of benefits associated with various interventions
across a range of settings. It is also important to determine the direct impact of household energy interventions
on poverty reduction and the pathways by which this is
mediated, both at the household/community level as well
as at the macroeconomic level for countries.
In conclusion, work on household energy solutions
for developing countries is at a critical stage. There is a
strong and growing case for action. Improved technologies
and cleaner fuels are already available or require relatively modest investment for innovation. Growing efforts
to find ways to reduce global warming emissions that also
assist poor countries provide another opportunity. Improvements in household energy will contribute directly
to achieving the Millennium Development Goals, particularly child mortality reduction (Goal 4) and extreme
poverty reduction (Goal 1). The principal challenge is to
achieve a rapid but sustainable increase in access to
cleaner, more efficient household energy among the 3
billion people in the world whose development prospects
are held back by practices that affluent nations have long
since left behind. This will require wider awareness of
the problem, increased political commitment, and careful
deployment of substantially greater financial resources
than are currently allocated to this critical aspect of
See also: Indoor Air Pollution Attributed to Solid Fuel Use
for Heating and Cooking and Cancer Risk, Solid Fuel:
Health Effects, Solid Fuel Use: Health Effect.
Further Reading
Albalak R, Bruce NG, McCracken JP, and Smith KR (2001) Indoor
respirable particulate matter concentrations from an open fire,
improved cookstove, and LPG/open fire combination in a rural
Guatemalan community. Environmental Science and Technology 35:
Bruce NG (2005) Reducing the health impacts of biomass fuel use in
poor countries: Do the health services have a role? African Journal of
Respiratory Medicine 1: 18--24.
Bruce NG, Rehfuess E, Mehta S, Hutton G, and Smith KR (2006)
Indoor air pollution. In: Jamison DT, Breman JG, Measham AR, et al.
(eds.) Disease Control Priorities in Developing Countries, 2nd edn.,
pp. 793--815. New York: Oxford University Press.
Edwards R, Liu Y, He G, et al. (2007) Household CO and PM measured
as part of a review of China’s National Improved Stove Program.
Indoor Air 17: 189--203.
Household Energy and Health (2007) Six articles on field monitoring
and evaluation of stove programs for air pollution and energy use.
Energy for Sustainable Development 11(2): 3--81.
Hutton G, Rehfuess E, Tediosi F, and Weiss S (2006) Evaluation of the
Costs and Benefits of Household Energy and Health Interventions at
Global and Regional Levels. Geneva: World Health Organization.
International Energy Agency (2002) Energy and poverty. World Energy
Outlook 2002. Paris: International Energy Agency.
McDade S (2004) Fueling development: The role of LPG in poverty
reduction and growth. Energy for Sustainable Development 8:
Mehta S and Shahpar C (2004) The health benefits of interventions to
reduce indoor air pollution from solid fuel use: A cost-effectiveness
analysis. Energy for Sustainable Development 8: 53--59.
Rollin H, Mathee A, Bruce NG, Levin J, and von Schirnding YER (2004)
Comparison of indoor air quality in electrified and un-electrified
dwellings in rural South African villages. Indoor Air 14: 208--216.
Saksena S, Thompson L, and Smith KR (2004) Indoor Air Pollution and
Exposure Database: Household Measurements in Developing
Countries. ¼ 33
(accessed July 2010).
Sinton JE, Smith KR, Peabody JW, et al. (2004) An assessment of
programs to promote improved household stoves in China. Energy
for Sustainable Development 8(3): 33--52.
Smith KR, Gu SH, Huang K, and Qiu DX (1993) 100 million improved
stoves in China: How was it done? World Development 21(6):
Smith KR, Mehta S, and Feuz M (2004) Indoor air pollution from
household use of solid fuels. In: Ezzati M (ed.) Comparative
Quantification of Health Risks: Global and Regional Burden of
Disease Attributable to Selected Major Risk Factors. Geneva: World
Health Organization.
World Health Organization (2008) Evaluating Household Energy and
Health Interventions: A Catalogue of Methods. Geneva: WHO. (accessed August 2009).
Relevant Websites
Disease Control Priorities Project.
Energy Sector Management Assistance Project: ESMAP (World
Household Energy Solutions in Developing Countries ¼ CJK68t3H8ZUCFQyR1Qodbl9xew
GTZ: Household Energy for Sustainable Development.
Household Energy and Health Studies in Guatemala, China, India,
and Nepal.
Household Energy Development Organisation Network (HEDON).
LP Gas Rural Energy Challenge.
Partnership for Clean Indoor Air.
Project Gaia: Promotion of Ethanol Stoves.
SNV: Promotion of Domestic Biogas.
The Shell Foundation (see Our Programmes/Breathing Space).
World Health Organization, Department of Public Health and
Environment, Indoor Air Pollution.