Human responses to high levels of carbon dioxide and air temperature.
In this study, 30 subjects were exposed to different combinations of air temperature (Ta : 24, 27, and 30°C) and CO2 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 Ta  = 24°C, exposure to 30°C at all CO2 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 Ta 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 CO2 from 8000 to 12 000 ppm at all Ta 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 Ta and CO2 concentration on human responses was identified.
['Tu|Zhijun|Z|0000-0002-9645-9216', 'Li|Yong|Y|', 'Geng|Shibin|S|', 'Zhou|Kun|K|', 'Wang|Ruihai|R|', 'Dong|Xian|X|']
D016902:Air Pollution, Indoor D001794:Blood Pressure D002245:Carbon Dioxide D004781:Environmental Exposure D006358:Hot Temperature D006801:Humans D006813:Humidity D013647:Task Performance and Analysis D013696:Temperature D014691:Ventilation
air temperature physiological responses cognitive performance CO2 concentration subjective ratings underground confined space