The effects of elevated carbon dioxide concentration and mental workload on task performance in an enclosed environmental chamber

In an enclosed environmental chamber, fifteen participants were recruited to investigate the effects of elevated carbon dioxide (CO₂) concentration and mental workload on their task performance. During each CO₂ condition, the Multi-attribute Task Battery (MATB) tasks with low, medium, and high mental workload were separately carried out in the order designed by the Latin square method. The MATB task performance was synchronously collected, and the subjective mental workload was measured immediately after each task based on the National Aeronautics and Space Administration-Task Load Index (NASA-TLX) scale. The generalized additive mixed effect model (GAMM) results showed that the subjective mental workload was not associated with CO₂ concentration and was positively related to the designed mental workload of tasks. The elevated mental workload of task had a significant inverted U-shaped effect on the MATB task performance, which aligned with prior studies and indicated that the medium mental workload was conducive to improving task performance. The MATB task performance declined significantly when the CO₂ concentration increased from 1500 ppm to 3500 ppm, but there was no significant difference between 3500 ppm and 5000 ppm, or 1500 ppm and 5000 ppm.