The Swahili word mazuku means roughly “evil wind” and refers to a lethal phenomenon around Lake Kivu on the border between the Democratic Republic of the Congo and Rwanda.
Carbon dioxide from volcanic activity leaks from cracks in the ground. The gas is heavier than air and collects in hollows, cellars, and low-lying areas, forming invisible and sometimes deadly pools, especially on windless nights. High concentrations of CO2 produce dizziness, nausea, confusion and weakness. Unwary victims who do not leave immediately tend to collapse then die in the high concentration of gas close to the ground.
One study found mazuku killed about eight people a year, and blamed the lack of warning signs and visitors’ ignorance.
A paper in Nature notes that involving local residents by getting them to act as citizen scientists through reporting new cracks in the ground and other signs of volcanic activity, not only provides useful scientific data but also helps warn the community of hazards. This could prove important in future.
Population growth and urban sprawl mean there are now about a million people in the affected area. Increased volcanic activity can lead to “outgassings” and a higher risk of mazuku, so an improved awareness of the dangers and how to avoid them could save many lives.