The world's deadliest pollution does not come from factories billowing smoke, industries tainting water supplies or chemicals seeping into farm land. It comes from within people's own homes. Smoke from domestic fires kills nearly two million people each year and sickens millions more, according to the World Health Organisation (WHO).
A new UN project has now been set up to try to reduce this appalling toll. It aims, over the next nine years, to put 100 million clean cooking stoves into homes in the developing world.
The WHO ranks the problem as one of the worst health risks facing the poor. In low-income countries, such as those in Africa and Asia, indoor smoke from cooking has become the sixth biggest killer. Globally, it kills more people than malaria, and nearly as many as Aids – and far more insidiously than either.
The problem is partly the fuels used, partly the lack of ventilation. Cooking on open fires and stoves without chimneys, using basic fuels such as wood, animal dung, crop waste and coal, emits hazardous smoke that causes irreversible ill health and killer diseases. Small soot or dust particles penetrate deep into the lungs, causing lung cancer, child pneumonia and chronic obstructive pulmonary disease. Women and children, whose traditional place is in the kitchen, are the the most common victims.
Stoves and open fires are the primary means of cooking and heating for nearly three billion people. In India, some 400,000 people die each year from the toxic fumes. In Africa, 500,000 children under the age of five die from pneumonia attributable to indoor air pollution, according to the WHO. And in Afghanistan, smoke from cooking and heating fires killed 20 times as many people in 2010 as did the ongoing conflict.
Of the two million people that die every year from household pollution, 44 per cent of these are from childhood pneumonia, the single biggest cause of children's death in the world. Fifty-four per cent of deaths are from chronic obstructive pulmonary disease and 2 per cent from lung cancer.
Dr Nigel Bruce, consultant of WHO, said: "The problem is caused by the inefficiency of traditional open fires and stoves resulting in very incomplete combustion of wood, dung and other solid fuels that a majority of people in developing countries rely on for their everyday cooking needs. While people are gradually becoming more aware of the devastating health impact of indoor pollution from cooking, there is still much more to be done.
"In terms of what we call disability adjusted life years, which combines the burden due to death and illness in a single index, indoor smoke from solid fuels in low-income countries ranks fifth, behind childhood underweight, unsafe water, sanitation and hygiene, unsafe sex and insufficient breastfeeding. This is significant, because it takes into consideration the many years of life lost from childhood pneumonia, one of the most important diseases caused by solid fuel smoke pollution.
"The problem is not going away quickly and it won't without concerted effort. The pace of transition to clean-burning stoves and fuels is worryingly slow, and with population figures increasing, the numbers of people who rely upon biomass fuels is going to increase with current trends."
The UN Foundation's Global Alliance for Clean Cookstoves was launched a few months ago to help to advance large-scale adoption of clean and safe household cooking solutions as a way to save lives, improve livelihoods, empower women and reduce climate change emissions. The United States has committed $50m (£31m) over five years to the project, which is bringing together UN agencies, stove manufacturers, non-profit organisations, financiers, governments and others to help to enable universal adoption of clean stoves.
Leslie Cordes, interim executive director of the alliance, said: "Exposure to smoke from traditional cookstoves and open fires causes 1.9 million premature deaths annually. That's one death every 16 seconds, with many more sickened. The alliance is working with public, private and non-profit partners to overcome the market barriers that hamper the production, deployment, and use of clean cookstoves in the developing world."
Between now and 2020, the adoption of new, low-emission advanced biomass stove technologies, or a mix of clean fuel and biomass stoves, could avert 600,000 child pneumonia deaths in sub-Saharan Africa and Latin America, said the WHO. Afghanistan is a glaring example of the size of the task. More than 95 per cent of Afghanistan's 30 million people burn solid fuels, such as wood and coal, in their homes, making it one of the top 10 countries worst affected by indoor pollution. Dr Bashir Noormal, director general of the Afghan Public Health Institute, said smoke from heating and cooking in Afghan homes "causes burns, carbon monoxide poisoning, respiratory illnesses and diseases and deaths. Inhalation of coal, wood and straw has been related to lung cancer and cancers of the head and neck".
He added: "Chronic exposure to wood smoke also significantly increases the risk of cervical cancer in human papillomavirus infected women." Human papillomavirus causes cervical cancer. But, in a country devastated by war, Dr Noormal said there was no data on how many cancer cases could have been caused by indoor pollution. This pollution mainly affects women and children because they spend the most time at home, said Afghanistan's acting Minister of Public Health, Dr Suraya Dalil. "Indoor pollution is one of the areas that threatens the survival of inhabitants," she said. "We're working to advocate for measures that would reduce indoor pollution, including things like provision of electricity, that increases the safety as well as reduces the pollution in the house."
Afghan families typically use a wood-burning bukhari, a drum-shaped stove made of thin metal, or a sandali, a pit of burning coal under a small table covered by a heavy blanket, under which people warm their feet. Honorita Bernasor, a Médecins sans Frontières emergency doctor at Kabul's Ahmed Shah Baba hospital, said winter in Afghanistan brought cases of burns and carbon monoxide poisoning. In December, the hospital treated nearly 100 cases of burns caused by heating or cooking. "We will be expecting more cases when the temperature goes lower," she said. "Bukharis are normally in the middle of the room and the children run around and put their hands everywhere. We see a lot of carbon monoxide poisoning as well."
Qudratullah Nasrat, an emergency room doctor at the same hospital, said some of the symptoms of carbon monoxide poisoning such as headaches and dizziness were well known to Afghans. "A lot of people treat themselves by sitting outside to breath the fresh air," he said. "They get to know the symptoms."