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CHARACTERIZATION OF TEMPERATURE AND RELATIVE HUMIDITY RESPONSES IN AN ENVIRONMENTAL CHAMBER

Abstract

J.P. Leeds, K.E. Coffman

University of Puget Sound, Tacoma, WA

Environmental chambers are an affordable solution for testing physiological responses to various environmental conditions in a laboratory setting for human exercise research. PURPOSE: To characterize the temperature (TEMP) and relative humidity (RH) responses of an environmental chamber in preparation for future studies. METHODS: Set points were selected by combining a high and low TEMP (HT & LT) and high and low RH (HH & LH) desired for future testing (HT-HH: 40°C-80%; HT-LH: 40°C-20%; LT- HH: 5°C-80%; LT-LH: 20°C-20%). First, the chamber started at room conditions and the digital TEMP and RH readouts of the chamber were recorded as the chamber reached each set point. Next, a pair of portable TEMP and RH sensors were calibrated and placed in opposite corners of the chamber to test whether there were differences in TEMP and RH values across the chamber. Lastly, the chamber door was opened for 15 s to test the response of the TEMP and RH during personnel entry/exit. RESULTS: The results presented here include the conditions which elicited the largest and/or smallest fluctuation or change for each aim. The chamber reached all set points in a minimum of 35 min (HT-LH) and maximum of 120 min (LT-LH). While TEMP remained relatively stable (largest fluctuation in LT-LH; 5.1 ± 0.6°C), RH fluctuated sinusoidally around its set point, and this was more substantial at LT-LH (21 ± 4%, range 16-30%) vs. LT-HH (80 ± 1%, range 78-82%). TEMP and RH were homogenous in both corners of the chamber in HT-LH (Δ2.0 ± 0.4°C; Δ3 ± 1%) and LT-LH (Δ1.5 ± 0.03°C; Δ3 ± 1%). In response to door opening, RH fell rapidly by ~2% but quickly recovered (~5 min) in HT-LH, whereas RH did not fall perceivably in LT-LH. When the chamber door was opened in HT-LH, TEMP fell slightly (~1oC) but quickly recovered (~5 min); TEMP did not change in LT- LH. CONCLUSION: The environmental chamber is able to reach a range of set points in ≤120 min, maintains an acceptable level of homogeneity in TEMP and RH across the chamber, and is minimally impacted by door opening. LT-LH requires a longer setup time and shows the largest fluctuations, likely because water is more difficult to evaporate at low TEMP. Future studies should aim to test similar conditions while one or more subjects are exercising in the chamber to determine the impact on TEMP, RH, and O2 and CO2 concentration.

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