It may come as a surprise to know that half of the global population uses biomass (wood, agricultural wastes and dung) and coal for cooking. For Sub-Saharan Africa where electrification rates outside of South Africa are only 28%, biomass and coal are the primary cooking fuels for over three fourths of the population. Combustion of unprocessed biomass fuels, especially in open or poorly ventilated stoves, emits high concentrations of pollutant mixtures – particulates, and carbon dioxide, methane, and carbon monoxide – associated with a number of respiratory and other diseases and is the leading cause of death among infants and children worldwide.
Since the task of cooking is mainly done by women and girls, it is they who face daily exposure to levels of pollution which are estimated to be the equivalent of consuming two packets of cigarettes a day (Kammen, 1995; Ezzati and Kammen, 2001).
Smoke from domestic fires kills nearly two million people each year, and sickens millions more. This places indoor air pollution as almost as critical a health threat as poor sanitation and AIDS, and a greater threat than malaria. Without systematic changes, household biomass use will result in an estimated 8.1 million Lower Respiratory Infection (LRI) deaths among young children in Sub-Saharan Africa alone, between 2000 and 2030 (Bailis, Ezzati, Kammen, 2007).
All of these factors highlight the critical need to evaluate the effectiveness of cookstoves at not only reducing emission, but in impacting health.
My own efforts in this area began over two decades ago when, inspired by an early and still one of the leading lights in this area, Kirk Smith . I conducted one of the first detailed studies that characterized exposure to indoor air pollution (IAP) from biomass fuels in Kenya.
With a series of exceptional students, Majid Ezzati and Robert Bailis, we launched efforts that included detailed monitoring of temporal and spatial patterns of particulate matter (PM) pollution, energy use, and exposure behaviors (time-location-activity budgets).
We used this data to estimate personal exposure  to particle pollution, which was in turn used to quantify exposure patterns by age group, gender, and participation in household activities. This data was also used to estimate the greenhouse gas (GHG) emissions from different stoves and fuels.
Through two years of weekly door-to-door visits by a trained local nurse to all study households, we were able to quantify the first-ever exposure-response relationship for biomass PM pollution and clinically diagnosed child pneumonia. What is so important about these quantitative and scientifically reviewed studies – and those done by a number of colleagues – is that they showed that even starting from very high pollution levels, that reductions in exposure had significant impacts, and in particular on the health of women and children, the primary cooks (Ezzati and Kammen, 2001).
In our analysis, we focused on both the global climate impacts of cooking and on the mortality impacts from particulates coming from these cookstoves. Scaling up from our work in Kenya, we found that under a business-as-usual (BAU) scenario, household indoor air pollution will cause 9.8 million premature deaths in Africa by 2030. Gradual and rapid transitions to charcoal avoid 1.0 million and 2.8 million deaths; similar transitions to petroleum fuels avoid 1.3 million and 3.7 million deaths.
Cumulative BAU household greenhouse gas emissions will be 6.7 billion tons of carbon by 2050, 5.6% of Africa's total. Large shifts to fossil fuels would reduce GHG emissions by 1-10%. Charcoal-intensive futures using current practices increase emissions by 140-190%; the increase can be reduced to 5-36% using currently-available technologies for sustainable production. It can get lower with a commitment to the most energy efficient stove and fuel combinations.
These regional assessments are vital because they not only show the carbon and climate impacts of efficient stove and fuel programs, but also highlight the opportunity to use carbon markets to reward locally sustainable programs – like expanding the number and size of efficient cookstove programs – with revenues from efforts to protect the climate.
Now we see a huge interest in cookstoves, household economics, health, and environmental sustainability. Most recently the United Nations Foundation has coordinated a series of planned examinations on the lessons of cookstove science, deployment, and community engagement, culminating in an exceptional global meeting  in Lima, Peru. The US government has been coordinating its stove activities, as the German, and other governments. At the World Bank the engagement in this area has been broad, coordinated by the Energy Sector Management Assistance Program (ESMAP), which joined a growing Global Alliance for Clean Cookstoves .
Next up will be an action plan to reach 100 million traditional stove users, and to quantify their health, economic, gender and climate impacts.