New Study Predicts Increasing Health Risks Due to Changing Climatic Conditions in the U.S. Southwest

Researchers at the George Washington University (GW) and Harvard University have conducted the first study to quantify how changing climatic conditions in the U.S. Southwest and northern Mexico may impact airborne dust levels and human health. Their study shows that the higher temperatures and decreased precipitation predicted at the end of this century are likely to be accompanied by significant increases in hospital admissions and premature deaths due to rising levels of fine dust in the atmosphere.
 
“The U.S. Southwest has been seeing some of the fastest population growth in the U.S., and the area is projected to experience severe and persistent droughts in coming decades due to human-caused climate change,” said author Susan Anenberg, PhD, an Associate Professor of Environmental and Occupational Health at  GW’s Milken Institute School of Public Health (Milken Institute SPH). “We know that droughts are associated with increases in exposure to small dust particles (PM2.5) and minerals. These pollutants can penetrate deeply into the lung and are linked to asthma, respiratory inflammation, and cardiovascular mortality, as well an illness that is on the rise in the Southwest known as Valley Fever.”
 

Pattanun “Ploy” Achakulwisut, PhD, now a postdoctoral researcher at the Milken Institute SPH, led the study while she was at Harvard University in collaboration with Anenberg and Loretta Mickley, PhD, from Harvard’s School of Engineering and Applied Sciences. The research team analyzed observational data on airborne fine dust levels and regional drought conditions collected over the past 16 years. They found that years with higher-than-normal fine dust levels in the U.S. Southwest correspond to anomalously dry soil moisture conditions across southwestern North America, including areas spanning the Chihuahuan, Mojave, and Sonoran Deserts. They used the observed dust-drought relationships, combined with information from 22 climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5), to estimate future changes in fine dust levels for the best- and worst-case climate change scenarios included in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Their work also incorporates information about the well-documented adverse health impacts of PM2.5 exposure to project the associated burden of illness and premature mortality.

“Our research suggests that premature deaths could rise by between 20 to 130 percent, and annual hospitalizations due to cardiovascular and respiratory illness could grow by between 60 and 300 percent by 2100, depending on different scenarios of greenhouse gas emissions and accounting for future growths in population and incidence rates of the various health endpoints,” said Achakulwisut. “Our results indicate that future droughts driven by climate change could pose a potentially substantial public health burden in the U.S. Southwest, a climate penalty that is not yet widely recognized. This is important information for policymakers to have.”
 
Drought-sensitivity of fine dust in the U.S. Southwest: Implications for air quality and public health under future climate change” is available online and will be published in print in Environmental Research Letters.