The human body emits a wide range of chemicals, including CO₂ and isoprene. To examine the impact of cognitive tasks on human emission rates of CO₂ and isoprene, we conducted an across subjects, counterbalanced study in a controlled chamber involving 16 adults. The chamber replicated an office environment. In groups of four, participants engaged in 30 minutes each of cognitive tasks (stressed activity) and watching nature documentaries (relaxed activity). Measured biomarkers indicated higher stress levels were achieved during the stressed activity. Per-person CO₂ emission rates were greater for stressed than relaxed activity (30.3 ± 2.1 vs. 27.0 ± 1.7 g/h/p, p = 0.0044, mean ± standard deviation). Isoprene emission rates were also elevated under stressed vs. relaxed activity (154 ± 25 µg/h/p vs. 116  ± 20 µg/h/p, p = 0.041). Chamber temperature was held constant at 26.2 ± 0.49 ◦C; incidental variation in temperature did not explain variance in emission rates. Isoprene emission rates increased linearly with salivary-alpha amylase levels (r² = 0.6, p = 0.02). These results imply the possibility of considering cognitive tasks when determining building ventilation rates. They also present the possibility of monitoring indicators of cognitive tasks of occupants through measurement of air quality.  

Please change the working directory as per the directory to which you download the folder.

For running the .R files, install all the packages mentioned in the functions.R file.