Model-Based Assessment of Geogenic Radon Exposure in Chaco Canyon and Adjacent Ancestral Puebloan Residential Settings
Abstract
Naturally occurring radon-222 and its short-lived alpha-emitting progeny are important sources of environmental radioactivity in enclosed, earth-contact spaces, yet their potential relevance to archaeological built environments has rarely been quantified. Here we evaluate chronic radon exposure in Chaco Canyon, where Ancestral Pueblo people occupied earth-contact and semi-subterranean rooms associated with Pueblo Bonito and other great houses during AD 850--1150. We developed a Chaco-specific source-to-risk model using an ensemble of uranium-miner radon risk functions to link uranium- and radium-bearing geology, soil-gas radon production, diffusion- and advection-driven indoor entry, ventilation, dust/smoke-enhanced progeny exposure, floor-level occupancy, premodern survival, and radon-associated lung-cancer mortality. The model converts indoor radon scenarios to working-level-month exposure and propagates risk through reconstructed birth cohorts and competing mortality. Under the reference population trajectory, modeled exposure produced notable conditional lifetime lung-cancer risk among long-lived residents and an age-structured mortality burden during AD 850--1150. Because survival into older adulthood was limited, realized population-level burden remained demographically constrained even where conditional individual risk was elevated. We do not propose radon as a primary cause of Chacoan depopulation, Pueblo Bonito decline, or regional abandonment. Rather, the results indicate that elevated radon in selected earth-contact microenvironments could have imposed a chronic, elder-concentrated health burden within an already stressed social and ecological system, making geogenic radioactivity a testable contributor to cumulative vulnerability.
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BibTeX
@misc{silber2026modelbased,
title = {{Model-Based Assessment of Geogenic Radon Exposure in Chaco Canyon and Adjacent Ancestral Puebloan Residential Settings}},
author = {Reynold E. Silber and Elizabeth A Silber and Carman Melendrez and Robert Silber},
howpublished = {EarthArXiv},
year = {2026},
month = sep,
doi = {10.1016/j.jenvrad.2026.108174},
url = {https://eartharxiv.org/repository/view/15264/},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Model-Based Assessment of Geogenic Radon Exposure in Chaco Canyon and Adjacent Ancestral Puebloan Residential Settings
AU - Reynold E. Silber
AU - Elizabeth A Silber
AU - Carman Melendrez
AU - Robert Silber
PY - 2026
DA - 2026/09/29
PB - EarthArXiv
DO - 10.1016/j.jenvrad.2026.108174
UR - https://eartharxiv.org/repository/view/15264/
AB - Naturally occurring radon-222 and its short-lived alpha-emitting progeny are important sources of environmental radioactivity in enclosed, earth-contact spaces, yet their potential relevance to archaeological built environments has rarely been quantified. Here we evaluate chronic radon exposure in Chaco Canyon, where Ancestral Pueblo people occupied earth-contact and semi-subterranean rooms associated with Pueblo Bonito and other great houses during AD 850--1150. We developed a Chaco-specific source-to-risk model using an ensemble of uranium-miner radon risk functions to link uranium- and radium-bearing geology, soil-gas radon production, diffusion- and advection-driven indoor entry, ventilation, dust/smoke-enhanced progeny exposure, floor-level occupancy, premodern survival, and radon-associated lung-cancer mortality. The model converts indoor radon scenarios to working-level-month exposure and propagates risk through reconstructed birth cohorts and competing mortality. Under the reference population trajectory, modeled exposure produced notable conditional lifetime lung-cancer risk among long-lived residents and an age-structured mortality burden during AD 850--1150. Because survival into older adulthood was limited, realized population-level burden remained demographically constrained even where conditional individual risk was elevated. We do not propose radon as a primary cause of Chacoan depopulation, Pueblo Bonito decline, or regional abandonment. Rather, the results indicate that elevated radon in selected earth-contact microenvironments could have imposed a chronic, elder-concentrated health burden within an already stressed social and ecological system, making geogenic radioactivity a testable contributor to cumulative vulnerability.
ER -