A jury-rigged smoke sampling system put together by two researchers from the University of Illinois, Urbana-Champaign, has revealed that the primitive cooking stoves used in the developing world may be much bigger contributors to the greenhouse effect than previously thought.
In the past, laboratory tests have been used to measure the pollutants from cooking fires because field tests have been difficult to conduct. But researchers Tami Bond and Chris Roden decided to get a more accurate measure by knocking together a portable battery-operated sampling cart, which included sensors for measuring carbon dioxide and carbon monoxide, particle soot absorption, particle color and concentration.
Reporting the results in the journal Environmental Science & Technology, the researchers said that the stoves in Honduras produced double the expected amount of smoke particles. “We expected field measurements to be different from lab measurements, and we suspected the amount of black carbon from these stoves would be higher than open burning, but we were surprised by how much,” Roden said.
Previous estimates of sooty particles from burning firewood were put at around 800,000 metric tons of soot worldwide a year. That figure may now need to be doubled. Put into perspective, diesel cars and trucks generate about 900,000 metric tons of soot annually. In total, from all sources, about 8,000,000 tons of soot is emitted into the world’s atmosphere each year.
It’s estimated that as many as 400 million cooking stoves – fueled by wood or crop residue – are in use daily worldwide. The sooty particles they produce are darker than those from grassland or forest fires and have a climate warming effect because they absorb solar energy and heat the atmosphere. As well as their effect on the climate, Roden said that smoke from cook stove fires is a major cause of respiratory problems, eye infections and tuberculosis. “Emissions from wood cook stoves affect the health of users – especially of women and children – neighborhood air quality, and global climate. Reducing these emissions, through the use of cleaner burning stoves and fuels, should have far-reaching benefits,” Bond added.
Roden agreed, but said that any new cook stoves; “must be well designed and properly tested. They must be built with local traditions and practices in mind and must be easy to use, or they may become expensive doorstops.”