5.1. Introduction
Although the scope of these guidelines is global, the main focus has been on the health impacts from household fuel combustion in LMICs where the burden is by far the greatest. Consequently, the primary concern of WHO in providing technical support for implementation of the guidelines lies with LMICs, recognizing that higher income countries identifying health risks (mainly from solid heating fuels) will have mechanisms and resources to address these more easily. WHO acknowledges that – particularly for lower income and/or more rural populations – implementing these recommendations will require coordinated effort from ministries, other national stakeholders (NGOs, public and private sectors), and often input from international development and finance organizations. WHO will work with countries to support this process through its regional and country offices, and is preparing web-based guidance and tools that build on the evidence reviews used to inform these guidelines.
In addition to the above general support, WHO will work closely with some of the countries most affected by this issue to learn from initial stages of implementation, and use this experience to revise the guidance and tools (see also updates, Section 6.2).
An overview of the main areas in which WHO will provide technical support for implementation is provided below. Further details are available at: http://www.who.int/indoorair/guidelines/hhfc.
5.2. Approach to implementation: collaboration and the role of the health sector
The multiple issues involved in achieving equitable and lasting adoption of cleaner and safer household energy demand inputs from a range of agencies. An effective mechanism for policy coordination at government level is therefore a critical first step. In most countries, mechanisms for cross-sectoral collaboration in respect of a range of policy areas involving ministries and other stakeholders are likely to be in place, and these can be built upon as needed.
To date, many ministries of health have not engaged fully with this problem, in part because it is considered the responsibility of other sectors including energy, environment and finance. However, in many cases cooking and heating technologies that improve energy efficiency to levels needed to reduce deforestation and deliver fuel and time savings for households, do not yield air quality improvements to levels that afford health protection. If the potential for large health benefits is to be realized, the health sector needs to play a key role. This can include assessing and communicating health risks and benefits, but in particular ensuring that proposed intervention technologies, fuels and other changes really do improve health and safety, and making the most of opportunities to change household energy practices through direct interactions between the public and health services. The health sector input can only be effective, however, if such efforts are coordinated with policy to ensure affordable supply of, and support for, the cleaner and more efficient household energy options required. WHO will work with ministries of health to support this role, and to ensure that health perspectives are strongly represented in policies.
5.3. Needs assessment
The first step in policy planning is assessment of household energy use and access to cooking, heating and lighting technologies and fuels across the country, and identification of associated health risks. WHO has a number of resources that can contribute to building a national needs assessment, including the following which are available at: http://www.who.int/indoorair/guidelines/hhfc.
The household energy database which compiles nationally representative survey-based information on primary fuels used for cooking for all countries, and increasingly including data on heating and lighting fuels.
A database of measured pollutant concentrations (mainly PM and CO) in kitchens, with some values for outdoor levels and personal exposure, derived from a recent systematic review (Review 5). This will be periodically updated.
National estimates of numbers of premature deaths from child ALRI, IHD, stroke, COPD and lung cancer, attributable to HAP exposure are available through the WHO Global Health Observatory. Current estimates are for the year 2012, and these will be periodically updated.
WHO can provide technical support on planning for additional studies to provide more detailed and locally specific information. The planning tool outlined in Section 5.5 will include an assessment of key factors that influence the adoption and sustained use of new technologies and fuels, and this should be an important part of the needs assessment.
Section 5.7 describes elements of a M&E strategy, for which improved household energy survey instruments are being developed. These will, in due course, provide better quality information on the mix of fuels and technologies that homes are using.
5.4. Intervention options and strategies
5.4.1. Roles of clean fuels and lower emission solid fuel stoves
As addressed by Recommendation 2, it is recognized that rapid transition to household energy solutions that consistently meet WHO AQG values for PM2.5 will take time, especially in low-income settings. Intermediate steps may be inevitable and appropriate to promote this transition to cleaner energy (). Nevertheless, given the current evidence on the performance of so-called ‘improved’ solid fuel stoves in everyday use (Review 6), widespread and near-exclusive use of clean fuels will be required to achieve air quality in and around homes that meets the WHO AQG for PM2.5.
Examples of solid fuel stoves. Solid fuel stoves A range of types of solid fuel stoves are available, including simple combustion types with and without chimneys (top left), standard ‘rocket’ stoves (top right) and more advanced combustion (more...)
LPG is the clean fuel alternative most widely available for replacing solid fuels and/or kerosene in households currently relying on them. In many such homes, other clean fuels may be impractical (e.g. piped natural gas in rural areas, electricity where reliable supply is unavailable, or biogas for homes with no farm animals) or more expensive (e.g. electricity). To date, however, there have been relatively few studies of LPG evaluating the acceptability, sustained use, impacts of policy on affordability and supply, impacts on HAP exposure and health, and safety regulation issues. Given the potentially wide availability of this fuel, it is important that such studies are carried out as soon as possible.
Other clean fuels will also make an important contribution. For example, in some areas of India with more reliable electricity supplies, inexpensive induction stoves are becoming increasingly popular and affordable for regular cooking due to their high efficiency. Comparative studies evaluating the use, supply, costs and impacts of electricity and other fuels including biogas, natural gas, alcohol fuels (ethanol, methanol), dimethyl ether (DME) and solar cookers, should also be a priority ().
Modern gaseous and liquid fuels and electricity. Clean fuels include biogas, ethanol, LPG, natural gas and electricity. Solar cook stoves may also play a part where conditions are suitable for meeting user needs. Policy on household energy should focus (more...)
As recognized in these guidelines, and specifically in Recommendation 2, which addresses policy during transition, improved solid fuel stoves will continue to make an important contribution to the needs of a substantial proportion of lower income and rural homes where primary use of clean fuels is not feasible for some time to come. Work to develop substantially improved solid fuel stoves should continue in parallel with, but not hinder or displace, efforts to encourage transition to clean fuels. The contribution of solid fuel stoves to the mix of devices and fuels promoted will depend on the completeness of combustion that can be achieved when such technologies are in everyday use (as demonstrated through emissions testing), and the consequent reductions in health risks.
Three randomized clinical trials are currently under way, all studying the impacts of improved stoves (both standard natural draught rocket-type and fan-assisted) on birth outcomes (preterm birth, birth weight) and ALRI. The trial locations together with the lead investigating institutions, principal investigators, intervention technologies and fuels, main health outcomes and trial registration numbers are provided in below. Three of these (Ghana, Nepal and Nigeria) will also include a clean fuel (LPG or ethanol) in the trial. The findings of these trials are expected to make an important contribution to the evidence base for intervention strategies.
Randomized clinical trials testing health impacts of reducing HAP exposure that are in progress.
5.4.2. Patterns of adoption of new energy and fuel technologies across society
The use of energy in the home is characterized by use of several technologies and fuels for multiple household needs including cooking, heating, lighting, boiling water, bathing and washing clothes, and food processing. Studies consistently show that new technologies and fuels tend to be absorbed into existing practices and rarely displace older methods completely, at least not in the short-term. Furthermore, the rate of adoption and sustained use of more modern, clean and efficient household energy will differ according to socioeconomic circumstances, geography and other factors, as illustrated schematically for the primary cooking stove in .
Hypothetical, simplified scenarios for rates of transition from predominantly traditional solid fuel use for cooking in the home to low-emission improved solid fuel stoves, clean fuels and/or electricity across three differing socially and geographically (more...)
Similar considerations will apply to transitions in fuels and technology used for meeting heating and lighting requirements, and all of these need to be taken into consideration in assessing the expected impacts on total emissions and hence HAP and exposure levels.
Thus, when developing policy, it is important to recognize that multiple devices and fuels will be used, and that families will need to adapt to changing incomes, energy supplies and prices, seasonal and other needs, by altering the mix (). Requirements must also be assessed – cooking and lighting are required by all homes, but some other needs, including heating and food processing (e.g. drying), will vary according to location, season and the nature of the local economy.
Fuel and technology stacking. An example of multiple fuel use in a home in rural Mexico, with a wood fired chimney stove used next to an LPG stove.
Policy should therefore seek to maximize the share of household energy that is obtained from clean fuels, and work to ensure that these are (and remain) available and affordable. Where solid fuel technology continues to be needed, the lowest emission options – consistent with meeting household needs, safety and costs – should be developed and promoted. For those households needing to rely on these interim steps of improved solid fuel stoves, assessment should also be made of what can be done as soon as possible to prepare the way for starting or increasing the use of clean fuels.
5.4.3. Evaluating intervention options
Many factors need to be considered when evaluating alternative technologies and fuels, including acceptability, costs, emissions and safety. The most critical outcome for securing health benefits is human exposure to health damaging levels of emissions and the consequent risk of adverse health outcomes. WHO will support the development of tools to assist with this assessment, including an enhanced version of the emissions model, and an intervention assessment tool.
Enhanced emissions model
The single-zone emissions model, which underpins Recommendation 1, is described in Review 3. The following additional steps were recommended to increase the value and applicability of this model:
Further empirical work to obtain more regionally representative data on the key model inputs, that is, on kitchen volume, air exchange rates and duration of use of the device. This will allow calculation of ERTs based on these regional data.
Development of an interactive version which will allow users to enter locally-sourced data, and to determine emission rates for different percentages of homes meeting the AQG values.
Further details of the plans for, and status of, these developments to the model are available at: http://www.who.int/indoorair/guidelines/hhfc.
Intervention assessment tool
A number of tools are in development that are designed to estimate expected health benefits of alternative technologies and fuels. These are based on evidence reported in Review 4, specifically the IER functions, which allow estimation of the reduction in risk of several important health outcomes (child ALRI, IHD, stroke, lung cancer and COPD) following a specified reduction in exposure to PM2.5. Further details on progress with the development and testing of these tools is available at: http://www.who.int/indoorair/guidelines/hhfc.
5.5. Policy for effective and sustained adoption
No matter how effective a stove or fuel is in terms of reduced emissions, if it is not used more or less exclusively and that use continued over time, health benefits will not be achieved. Review 7, and two recently published systematic reviews, (6, 29) have identified factors that influence the adoption and sustained use of improved solid fuel-burning stoves and four types of clean fuel (LPG, biogas, alcohol fuels, solar cookers).
These reviews show that a wide range of factors influence a household's adoption of new technology and/or fuel. Sole use of new technology and fuels–the extent to which it displaces existing arrangements–is also influenced by a wide range of factors. So, too, is maintenance of, and replacement of equipment when required. Review 7, which examined findings from more than 100 qualitative, quantitative and case studies, describes seven key domains influencing this process. These are summarized in .
Factors enabling or limiting uptake of cleaner cooking technologies. This framework illustrates how seven domains (D) – one relating to the characteristics of the intervention, two operating at the household/community level, and four operating (more...)
The review found that while some factors are critical for success, none guarantees this and context is also important. For example, a household will not adopt and use a new technology or fuel fully if this cannot be used to cook their usual types of food. On the other hand, one that meets these requirements will not be used long-term if there is no support for replacing parts, or the fuel supply is unreliable and/or not affordable. It is therefore important to consider all factors that are relevant to the fuel, technology and setting.
This new evidence provides the opportunity to develop a tool to assist with planning and evaluating policy to support effective and sustained adoption. Further details are available at: http://www.who.int/indoorair/guidelines/hhfc.
5.6. Standards, testing and regulation
These guidelines emphasize reduction of emissions with Recommendation 1 providing specific guidance on ERTs for PM2.5 and CO. Accordingly, systems (incorporating protocols, facilities and technical capacity) for carrying out testing in parts of the world where this is most needed, are critical for implementation of the guidelines.
An initiative to develop testing and associated voluntary standards for cook-stoves in LMICs was launched in 2012 as an International Workshop Agreement (IWA) under the auspices of the International Organization for Standardization (ISO), a first step in the process of developing full ISO standards, and providing a basis for regulation. This process, and the content of the IWA, are described in Annex 9. The health component of the voluntary standards included in the IWA was informed by WHO AQGs on specific pollutants (13, 14) and is based on emission rates using an earlier (and simpler) version of the model described in Review 3. Work is currently under way to develop testing centres and technical capacity on a subregional basis (). A new technical committee (ISO TC 285) was set up in June 2013 to update the IWA and develop international standards for cookstoves and clean cooking solutions (Annex 9). This process also allows for existing standards for household energy technologies to be incorporated.
Stove laboratory and testing.
This initiative on standards, and the associated testing, protocol development, technical capacity and facilities, is an important complement to these guidelines. In consequence, WHO is acting as a Category-A Liaison Organization for this ISO process, which will allow close interaction between the development of new standards and testing and the work of WHO on the guidelines and associated health-based evidence.
In developed countries where solid fuel (mainly biomass) stoves are used for heating, it will be important to further develop (if necessary) and enforce regulations and by-laws for the use of wood-burning appliances and other stoves and boilers.
5.7. Monitoring and evaluation: assessing the impact of these guidelines
Health gains will only be achieved if cleaner and safer household technologies and fuels are used widely, maintained properly and replaced when necessary. Experience has shown that, even where improved stoves or clean fuels are newly adopted, conditions for sustained use cannot be assumed. Active M&E are therefore vital, and will also provide an indication of the impact of the guidelines.
Global monitoring of household energy fuels and related estimates of HAP are compiled by WHO in its Global database for household fuels and IAP drawing on over 700 national and international surveys.(5) This database is used to inform a number of global estimates, including the MDG database the SE4All global tracking framework and burden of disease estimates. These guidelines have identified a number of ways in which global information on household energy and fuels should be improved to provide a more complete description of household energy adoption and use from the perspective of health risk assessment. The measurements of air pollution levels inside and outside homes are also important for M&E purposes.
WHO can support these M&E needs in several ways as set out below, with additional information available at: http://www.who.int/indoorair/guidelines/hhfc.
Household energy surveys
A range of approaches for monitoring transition towards cleaner household energy are described in Chapter 9 of the WHO air quality guidelines 2005 Global update (30), including the contribution of population-based household surveys within a hierachy of methods. Surveys are considered the most useful method for population-based monitoring, while studies of household pollutant concentrations, personal exposure and intervention use, provide the most detailed information at household level.
Current survey instruments, such as that used for the Demographic and Health Survey, which provide data included in the WHO global household energy database, need to be revised for a number of reasons including the inability currently to distinguish between effective and ineffective solid fuel stoves, and the need to capture information on secondary technology and fuel use for cooking, heating and lighting (). WHO is playing a leading role in this process, including for the UN's SE4All tracking framework1 Further details of progress with the development and testing of revised survey instruments is provided at: http://www.who.int/indoorair/guidelines/hhfc.
Household surveys. Interview-based surveys will continue to provide the most efficient means of monitoring household fuel and technology use across populations, and can be used to estimate HAP levels if allied to regionally representative studies measuring (more...)
Air quality and exposure measurement
While interview-based surveys are a practical means of monitoring population health risks (for example, fuel and stove use), even the best-designed surveys – on their own – cannot provide reliable estimates of actual pollutant concentrations in and around homes, nor of levels of personal exposure ().
Air quality and exposure measurements.
Recent published work from India (32), reported in Review 5, has shown that population-based interview surveys, combined with local studies measuring air pollutant concentrations and collecting information on the household variables included in the survey, can be used to make reliable estimates of air pollution at population level through modelling.
Whether used for modelling or to increase certainty about the HAP levels populations are being exposed to, air pollution measurement studies are likely to play an important part in any M&E strategy. WHO can provide technical support to ensure quality of measurement and comparability with other studies, and in the further development of protocols for wider application of these methods.
The measurement of air quality in the ambient (outdoor) environment can also play an important part in HAP control strategy. Review 5 found that, in Indian villages, average outdoor concentrations of PM2.5 can exceed 100 μg/m3. This implies that, no matter how low the emissions are within a particular house, indoor air quality will not meet WHO guideline levels due to high levels of outdoor air pollution entering the home (). Measurement of outdoor air quality should therefore be carried out more widely. In most rural, and many other settings where solid fuel use is widespread, household fuel combustion is an important (if not the main) source of pollution (3). Biomass (usually as charcoal or wood) and kerosene are also still commonly used for cooking and heating in urban and peri-urban areas and can be expected to make substantial contributions to ambient air pollution in cities where that is the case (3). It is therefore important to also monitor and evaluate the contributions to ambient air from household fuel combustion in cities, and to evaluate the use and impacts of clean fuels and energy technologies in these settings. WHO AQGs apply to pollutants in all settings and can serve as a basis for regulation and policy to support transition to low emission household energy.
Other sources of air pollution. Other sources of combustion such as brick kilns can contribute to air pollution in both rural and urban areas. In urban settings, there are likely to be contributions from a wider range of sources including traffic, industry, (more...)
Evaluation of health impacts
The M&E strategy should include ways to measure whether new technologies and fuels in everyday use are having the desired impact on important health outcomes. Studies should be carried out over several months of use at least; ideally for more than one year.
Levels of HAP and personal exposure, whether measured directly or estimated through modelling as described above, are useful indicators of risk. With improving evidence on exposure-response functions (for example, the IERs described in Review 4 and published) (23), it is now possible to estimate the reduction in important health outcomes – indeed this is what the intervention assessment tools are being designed to do (Section 5.4).
Reliably demonstrating the impacts on health outcomes such as child pneumonia or COPD introduces further complexities, many of which have recently been discussed by Martin and colleagues () (31). Such studies typically require substantial time and resources and use of optimal research designs (i.e. randomized trials) can impose constraints not easily accommodated within a mainly market-led scale-up. It is nevertheless essential to demonstrate the effects that large-scale programmes have on health outcomes. This is an important component of the M&E strategy and related research efforts; however, given the resources and technical challenges involved, it may be best managed with contributions from international partners.
Measuring health outcomes. Left: Measuring the incidence of major child health outcomes such as pneumonia requires the application of well-standardized diagnostic methods, assessment by a physician, and may also involve investigations including X-rays (more...)
Measuring the use, maintenance and replacement of technology and fuel interventions, and understanding why households make different choices is also important. Mixed methods, that is a combination of quantitative (e.g. stove-use monitors) and qualitative (in-depth interviews, focus group discussions) can provide a fuller picture of what is happening, and why. WHO will work with its partners, including the research community, to facilitate the development and application of improved M&E methods, and related research on health risks and intervention impacts. The findings of these research and evaluation activities will be incorporated into the guidelines, updating them where necessary, as described in Section 6.
Finally, it will also be important to carry out evaluation of programmes designed to address the adverse health and other impacts resulting from inefficient, polluting and unsafe household energy. This should assess the organization of the programme (structure), process, activities and impacts, drawing on many of the components described above.
5.8. Research needs
Development of these guidelines has made evident some key knowledge gaps and research needs. The most important of these needs are presented in the research recommendations in Sections 4.4 to 4.8. More detailed discussion of evidence gaps and research needs is included in the evidence reviews available at: http://www.who.int/indoorair/guidelines/hhfc.
Among the most important of these research needs are studies on the use and impacts of improved household energy technologies and clean fuels under real life conditions to further estimate effectiveness of interventions for the major causes of disease, including cardiovascular disease (an outcome for which very few studies are available). These studies can provide a better handle on cost-effectiveness of home energy interventions in comparison to other preventative interventions. Other relevant questions to be further investigated include the role of black carbon, the impacts of kerosene, and factors for sustained adoption.
WHO will work with its partners and the research community to help ensure these research priorities are addressed, that high quality and well-standardized methods are used, and results are incorporated into policy in a timely manner.
