"Volcanoes can affect populations without erupting, and we should care about this," Belgian volcanologist Dr Jacques Durieux told IRIN in Goma on Tuesday.
Durieux, who has been studying Nyiragongo and its nearby sister volcano, Mt Nyamulagira, for three decades, is presently working with the Observatoire Volcanologique de Goma (OVG) in collaboration with the UN Office for the Coordination of Humanitarian Affairs (OCHA).
Nyiragongo, located within Virunga National Park, last erupted on 17 January 2002. Three lava flows reached Goma, covering 15 percent of the city's surface and largely wiping out the central business district. While less than 50 deaths were believed to have been caused as a direct result of the eruption, some 400,000 people were either temporarily displaced or made homeless.
Since September 2002, Nyiragongo has been pumping out sustained levels of ash and smoke, with recent satellite measurements indicating that this included 50,000 mt of sulphur dioxide per day, along with other products that could not be measured by satellite, such as silicates, fluoride, and chlorides. In the case of chlorides, however, Durieux said that estimates could be made regarding its quantities using known ratios of Nyiragongo's typical output.
Durieux said that on the volcano itself, all vegetation had disappeared, while in various directions - 10 km to the east and south, and 25 km to the west, due to prevailing winds - his team had noted a "very important impact" on vegetation and crops. The region to the north is currently under study.
"The plants most affected are those most essential to food security, such as beans, bananas, sweet potatoes and maize," Durieux said, noting that his team had observed crop leaves burned and pocketed with holes caused by acid.
OVG will soon begin joint missions with the UN Food and Agriculture Organisation to better evaluate the volcano's effects on crops as well as livestock. An increased number of deaths among cattle and goats is suspected of having been caused by consumption of ash-coated grass, leading to deterioration of the animals' digestive system and poisoning by fluorosis, or excessive fluoride.
With regard to human health, Durieux said that local doctors had reported an increase in the prevalence of digestive problems and diarrhoea, a common effect of sulphur.
"Some 40,000 to 50,000 people living around the volcano rely on rainwater collected in cisterns. This water is polluted with ashes and lava needles (known as Pelee's hairs), and is becoming acidic," Durieux said. "The same water burning the vegetation is what people are drinking."
Durieux added that high measurements of fluoride emanating from both volcanoes were also ending up in the drinking water.
Local doctors have also noted an increase in respiratory ailments among their patients. Local medical authorities are currently collecting data from the region in an effort to piece together a clearer picture of the overall situation.
"I can give you a lot of information, but I cannot give you a medical opinion," Durieux said, adding that repeated efforts to collaborate with the World Health Programme (WHO) in this matter had so far been met with no response.
Asked for his reaction, Dr Chouaibou Ncharre, medical coordinator for WHO in eastern DRC, said that while he saw "no immediate danger" from the volcanic ash, long-term health effects could be possible. He told IRIN that his office had not received any request for assistance from the OVG, nor had it received any results from an environmental impact study that OVG had conducted. However, he said that if any such request were to be received, and financial and human resources could be mobilised to support the initiative, his office would be willing to investigate.
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