Research
Riyang Liu studies how environmental exposures are measured, distributed, and related to human health. His work connects three questions: How can we reconstruct exposure when observations are limited? What do finer estimates reveal about risks across populations and places? How can that evidence help address health risks in a warming climate?
Environmental exposure modeling and assessment
Health studies need pollution data that capture short-term fluctuations as well as long-term trends. Monitoring networks have gaps, and reconstructing exposure back to the 1980s is especially difficult because many historical inputs, including satellite observations, are unavailable. Riyang combines ground monitoring, geospatial predictors, machine learning, spatial and temporal feature design, and comprehensive model assessment to address these limitations.
His work on PM2.5, O3, and NO2 spans China, the United Kingdom, and the United States. Across these settings, he emphasizes careful combinations of methods, model tuning, and validation to develop exposure estimates for health research.
Environmental health and disparity analysis
Finer exposure estimates can be matched more closely to where people live, supporting comparisons that monitoring locations or coarse grids may miss. Riyang uses these estimates to examine how exposure varies across places and populations, including measures that capture the intensity and frequency of high-exposure days, not only annual averages.
This work includes analyses of rural and urban ozone exposure and mortality burden in the United States and racial and ethnic disparities in short-term NO2 exposure in California. Related collaborative studies in China have examined associations between ozone exposure and cardiovascular disease, depression, and cause-specific mortality. Together, these studies move from estimating environmental conditions toward understanding whom they affect and how those patterns change over time.
Heat exposure and human health
At Duke, Riyang is extending this exposure-to-health approach to heat. Working with the multidisciplinary Environmental Exposures & Kidney Health group, he is exploring how ambient and personal heat exposure can be linked with physiological measurements and cardio-kidney-metabolic health. As this work develops, his longer-term aim is to generate evidence that can inform practical heat adaptation for vulnerable populations.