A Combined Radiation and Cabin Air-Quality Framework for Neurocognitive Risk in Aerospace Environments: Introducing the Closed-Loop Life Support System (CLLSS) Concept and the “Shadow Zone”

<jats:p>Current aerospace life-support certification standards—the Environmental Control and Life Support System (ECLSS) framework for spacecraft and its aviation analogues—are built around physiological survival thresholds: partial pressure of oxygen, carbon dioxide (CO2) ceilings, and radiation dose limits set to prevent acute pathology. Crucially, however, these traditional standards fail to capture two subtler and cumulative neurocognitive risk pathways that our two independent research programs have separately identified: (1) a radiation-induced cognitive tipping point, in which cumulative geomagnetic storm-related radiation exposure above approximately 20 mSv correlates with a measurable rise mostly in dementia risk and characteristic low-voltage EEG patterns years after exposure; and (2) a “Shadow Zone” of subclinical cognitive degradation, in which cabin CO2, ozone, and trace-contaminant fluctuations that individually remain within certified ‘safe’ limits collectively produce a measurable decline in crew and passenger cognitive performance—showing a clear empirical inflection point near 12 hours of cumulative closed-loop exposure. Here, we propose that these two pathways are fundamentally linked through shared downstream neurophysiological markers (such as EEG spectral alterations, reaction-time slowing, and decision-making impairments). Ultimately, we argue for a unified, cognitively adaptive lifesupport standard that shifts certification logic from simple ‘survival’ to actual operational ‘performance.’ We outline a joint measurement framework (EEG and real-time O2/CO2/O3 monitoring) as the basis of a planned multi-site collaborative study.</jats:p>