Environmental CO2 Levels and Stroop Cognitive Performance Among Emergency Department Staff: An Observational Study

Introduction: The air we breathe at work may directly shape how we think and make decisions. Research suggests that even moderately high levels of carbon dioxide (CO₂) indoors,common in crowded spacescan slow cognitive performance. This is a criticalconcern for Emergency Departments, where staff operate under intense pressure, often in spaces with poor ventilation, while also battling the cognitive toll of shift work. Methods: To explore this in a real-world setting, we observed 85 doctors and nurses in the Emergency Department of Patan Hospital over five months. We continuously monitored CO₂ levels in their workspace. At the end of their shifts, staff completed a brief,computerized cognitive test (the Stroop Color-Word Test) to measure attention and mental flexibility. We then compared test performance between shifts with lower (<1000 ppm) and higher (≥1000 ppm) CO₂ levels. Results: A total of 85 Emergency Departments staffs were enrolled in the study out of which 50 (58.82%) doctors and 35 (41.17%) nurses. The mean age of participants was 32.4±6.8 years and 53 (62.12 %) were female. Out of 3 shifts that were observed 35 (41.17%) was day shift and 25 (29.41%) was night shift and remaining 25 (29.41%) staffs were taken at evening shift. Conclusions: Real-world Emergency Department staff exposed to moderate CO₂ elevations did not demonstrate clear impairment on Stroop interference metrics. Circadian disruption and fatigue appear to be stronger drivers of cognitive slowing than CO₂ within typicalranges.