Onja Davidson Raoelison is a postdoctoral fellow at Stanford University’s King Center on Global Development. (Credit: Onja Davidson Raoelison)
Beyond Fire and Smoke, Wildfires Might Just Spread Disease, Too
In California, Onja Davidson Raoelison is studying how extreme events like wildfires may spread pathogens through the water and air, a potential threat to human health.
Editor’s note: We’re reposting this article, published last month, in light of the California wildfires. The subject is a winner of our 2024 Women In Science Incentive Prize.
Growing up in France, Onja Davidson Raoelison often returned with her parents to Madagascar, where she was born. Renowned for its extraordinary biodiversity, the country is also notorious for its lack of clean drinking water. Raoelison’s physician parents taught residents there how to treat contaminated groundwater to prevent illness and death. Raoelison, now an environmental engineer, was motivated by those experiences to use science to improve lives in other meaningful ways.
“I was very interested in helping marginalized communities and low-income communities because I wanted to provide clean water to drink and also clean air to breathe,” she says. “That is the passion that still drives me.” Raoelison, whose first name means “waves” in Malagasy, brought that lifelong interest with her to California to pursue graduate studies, first at University of California, Los Angeles, where she earned a master’s degree and PhD, and now at Stanford’s King Center on Global Development as a postdoctoral fellow.
When she moved to California in 2018, Raoelison experienced the effects of wildfire firsthand when poor air quality kept residents indoors for days at a time. Fires were new to her, and the state’s dry climate was a stark contrast to Madagascar’s tropical one. Yet she drew parallels in terms of water quality. Wildfires, typically linked with poor air quality, also have a lasting impact on water quality, as the loss of vegetation and soil can lead to sediment, ash and pollutants flowing into “surface” water – any water that’s above ground – like streams, lakes and reservoirs.
At UCLA, Raoelison focused on reducing negative effects of wildfires on surface water quality by designing climate-resilient stormwater treatment systems. “I’m still very interested in providing safe water to people, and that’s why I got involved with water quality research,” she says. “As an engineer, I thought, ‘We have to find a solution to mitigate this impact.’” It was an ambitious project, says Raoelison, “but I was very glad that my research led to some positive outcomes.” She is hopeful the work will continue to inform scientists, policymakers, government agencies and the private sector downstream of fire-prone areas.
At Stanford, Raoelison has expanded her research to look at the effects of wildfires on air – specifically, on the problem of pathogens in wildfire smoke. Scientists once assumed that smoke was too hot to sustain microorganisms and was therefore sterile. But, Raoelison explained, recent studies show that wildfires can spread pathogenic microbes, including bacteria and fungi, through air and water, raising new concerns about human exposure to infectious agents. It’s an underexplored area that poses a significant global health threat, she said.
Working with the Stanford Department of Medicine, Raoelison first wants to identify the pathogens of interest and the distance they can travel during a wildfire. Knowing how they spread and what illnesses they can cause is also key to developing effective disease control and prevention strategies, she said. Raoelison’s research will inform scientists, utilities and healthcare workers and potentially influence policy regionally, nationally and even globally.
In addition to her parents, Raoelison was inspired by her great aunt, who was nominated for a Nobel Peace Prize two decades ago for promoting gender equality in Madagascar. “That’s why I also want to advocate for women,” she said. Raoelison has received several awards for her own commitment to supporting women and minorities in science. Through leadership and outreach, she wants to inspire girls to do anything they want to, including in male-dominated fields. “It’s intimidating, and some women don’t think that they can do things because we only see men there,” she said. “It’s very hard as a woman to have a voice and to express yourself, but it’s important for me to do that.” ◼️
