Tehran University of Medical Sciences International Journal of Occupational Hygiene 2008-5109 17 2 2025 12 09 80 87 Ehsan Garosi Department of Ergonomics, Faculty of health, Iran University of Medical Sciences, Tehran, Iran Adel Mazloumi Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Elham Entezarizarch Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran | Department of Industrial and Systems Engineering, University at Buffalo, Buffalo, USA Mojtaba K. Danesh Department of Occupational Health Engineering, Tehran University of Medical Sciences, Tehran, Iran 2025 04 06 2025 05 06 Background: The COVID-19 pandemic was a public health challenge that put health systems in a highly vulnerable situation, especially nurses working in intensive care units (ICUs) who provided care to patients with COVID-19. The goal of this study was to explore the lived experiences of ICU nurses regarding the nursing heightened job demands during the acute phase of the pandemic. Methods: The present study was conducted using a qualitative description design and purposive sampling method. The data of the study was collected through semi-structured interviews with 17 nurses in the special care departments of private and public hospitals in Tehran, during the earliest phases of COVID-19 pandemic, i.e., spring and summer of 2020. Data analysis was done using conventional content analysis method through MAXQDA 2018 software. The trustworthiness of the study findings was also confirmed by the researcher triangulation, peer review and member check. Results: Based on the lived experiences of the nurses, the challenges in the nursing job demands during the pandemic were demonstrated in 8 themes, including 1. Patients with complex, high-care needs, 2. ICU working at its limit, 3. Supervising and orienting the new workforce, 4. Care and treatment ambiguity, 5. Enduring the burden of PPE, 6. Covering for the unavailable colleagues, 7. Being emotionally involved with the patients and their families, and 8. Exhausting schedules. The breadth of these themes shows that ICU nurses faced unprecedented physical, mental and emotional demands during the period. Conclusion: The findings of this study reveal the profound impact of the COVID-19 pandemic on ICU nurses, highlighting the multifaceted extreme demands placed upon them. The results underscore the need for targeted support and resources to address the challenges faced by these frontline workers, including physical strain, emotional burden, and the complexities of patient care. It is crucial for healthcare systems to develop strategies that mitigate these pressures and provide robust support systems for nurses. Addressing these issues is essential to ensure well-being of ICU nurses and the sustainability of high-quality patient care during future crises. https://ijoh.tums.ac.ir/index.php/ijoh/article/view/683 https://ijoh.tums.ac.ir/index.php/ijoh/article/download/683/871