Human responses to high levels of carbon dioxide and air temperature

Abstract

In this study, 30 subjects were exposed to different combinations of air temperature (T a : 24, 27, and 30°C) and CO 2 level (8000, 10 000, and 12 000 ppm) in a high-humidity (RH: 85%) underground climate chamber. Subjective assessments, physiological responses, and cognitive performance were investigated. The results showed that as compared with exposure to T a = 24°C, exposure to 30°C at all CO 2 levels caused subjects to feel uncomfortably warm and experience stronger odor intensity, while increased mental effort and greater intensity of acute health symptoms were reported.However, no significant effects of T a on task performance or physiological responses were found. This indicated that subjects had to exert more effort to maintain their performance in an uncomfortably warm environment. Increasing CO 2 from 8000 to 12 000 ppm at all T a caused subjects to report higher rates of headache, fatigue, agitation, and feeling depressed, although the results were statistically significant only at 24 and 27°C. The text typing performance and systolic blood pressure (SBP) decreased significantly at this exposure, whereas diastolic blood pressure (DBP) and thermal discomfort increased significantly. These effects suggest higher arousal/ stress. No significant interaction effect of T a and CO 2 concentration on human responses was identified.

Physiological responses, self‐reported health effects, and cognitive performance during exposure to carbon dioxide at 20 000 ppm

“…Recent findings suggest significant increases in the intensity of reported headache, dizziness, agitation, fatigue, or feeling depressed with exposure to 12 000 ppm CO 2 47 . However, because relative humidity and room temperature were much higher compared to our study and many participants were exposed simultaneously in a rather small exposure room, symptom reports may have been influenced by the synergistic effects of these environmental factors 18 …”

“…When performing simple tasks with high vigilance requirements, CO 2 effects can be compensated by changing the speed‐accuracy strategy, thus maintaining accuracy at the expense of reduced speed. This was demonstrated by Tu and colleagues, 47 who found a statistically significant decrease in task speed but no changes in accuracy when CO 2 increased from 8000 ppm to 12 000 ppm in a text typing task requiring low self‐rated mental effort but not in a numerical calculation task requiring higher mental effort. In addition, Pang and colleagues 60 found a significant decrease in a simple reaction test at 3500 ppm CO 2 .…”

“…Twenty‐four persons were recruited for this study according to assumptions for a within‐subjects design experiment with repeated measures in previous studies 46,47 . In total, 8 male miners with frequent exposure to CO 2 from underground potash mining, and 16 only environmentally exposed subjects (8 men, 8 women).…”

“…Twenty-four persons were recruited for this study according to assumptions for a within-subjects design experiment with repeated measures in previous studies. 46,47 In total, 8 male miners with fre- The 2-tail significance level was set to p < 0.01. To assess the clinical significance/meaningfulness of statistically significant results, for the blood gas values the normal physiological range was given.…”

Experimental investigation of the dehumidification and decarburization performance of metal–organic frameworks in solid adsorption air conditioning

“…When the concentration of CO 2 in an air-conditioned room exceeds 0.1%, they will experience a headache and the electrolyte balance in the body is disrupted, causing blood acidosis, and at a CO 2 concentration of 2.0% to 3.0%, severe headache, respiratory distress and unresponsiveness will occur. [3][4][5] So, the air conditioning should be able to perform the following functions in summer: cooling, dehumidication and control of indoor CO 2 concentration. The traditional air conditioning system based on the principle of vapor-compression refrigeration cools the air below its dew point temperature in order to meet the needs of cooling and dehumidication at the same time, resulting in massive energy consumption.…”