Participants carried a backpack throughout their day equipped with devices that measured particulate matter and carbon monoxide—essentially, their exposure to ambient
and peak emissions. They self-reported respiratory symptoms and later responded to a survey about chronic health diagnoses.
“Exposure levels during cooking with traditional stoves were appallingly high,” says Dean, “and these peaks seem to be a really important factor in the respiratory symptoms that people experienced.” Yet, there was no reduction in chronic health outcomes or reported diagnoses, Dean says, nor did they observe any changes in blood pressure or pulse oxygenation.
But high-efficiency cookstoves nevertheless yielded big benefits, the researchers say. For one, they saved households money. Berkouwer and Dean calculate that charcoal purchases amounted to about 20 percent of household income, and high-efficiency cookstoves cut a household’s charcoal consumption by nearly half.
“Even if the health benefits to high-efficiency cookstoves were less than might be expected, there would still be massive financial savings,” says Dean. “These households spent a huge amount of their money on energy. The stoves retailed for $40 at the time of the study, and the savings were more than $120 during the first year. That return on investment can help people obtain a livelihood.”
A second benefit is that the stoves could be among the most cost-effective ways to reduce carbon emissions. Each high-efficiency cookstove reduces CO2 emissions by approximately 3.5 tons per year. The researchers’ data indicate that this is far more cost-effective than many other carbon-abatement technologies. They calculate the cost of emissions reduction for the stoves to be about $5 per ton, while electric vehicles, for instance, struggle to break $100 per ton.
Moreover, the technology is scalable. Billions of people worldwide rely on traditional stoves, and replacing those stoves with cleaner versions would cut millions of tons of carbon emissions. Switching to high-efficiency stoves could therefore play a significant role in reducing greenhouse-gas emissions, Dean says. He notes that there is also high additionality—the emissions reductions achieved by replacing cookstoves would not occur otherwise. Many households that received subsidized stoves otherwise wouldn’t have purchased one, and nearly four years after the study, about 85 percent of them still have it.