The World Health Organization considers air pollution the greatest environmental threat to public health, estimating that it kills more than 7 million people a year and attributing almost half of those deaths to household smoke from open fires and traditional stoves. To combat the problem, the United Nations and other groups have launched initiatives aimed at increasing access to clean-cooking methods—including subsidies for high-efficiency stoves.
But research by University of Pennsylvania’s Susanna B. Berkouwer and Chicago Booth’s Joshua Dean, who conducted a study in Nairobi, Kenya, suggests that when it comes to the health effects of air pollution, the spikes associated with traditional cooking methods are only one part of a larger picture. Study participants who adopted high-efficiency cookstoves self-reported lower levels of respiratory symptoms such as headaches and coughing. Yet switching to these cleaner stoves had no effect on blood pressure, blood oxygen levels, or medical diagnoses such as pneumonia.
The findings suggest that respiratory symptoms are associated with the peaks in air pollution caused by cooking, while clinical health symptoms such as blood pressure are more closely tied to average levels of pollution exposure. The city’s ambient pollution—from sources such as industrial activity, vehicles, and agricultural burning—remained the same during the 3.5-year-long study.
Beyond the improvements in respiratory symptoms that they bring, high-efficiency cookstoves have other climate and social welfare benefits that make their adoption worthwhile and could justify a subsidy, the researchers argue.