Yes, but normally if that's the case, the variables would need to be identified and not up to the reader to make educated guesses. This seems to be recurring problem with these types of studies (maybe because there aren't that many of them in the first place?)
Let's take this paper for instance "Modeling thermal responses in human subjects following extended exposure to radiofrequency energy"
It states the following;
"All studies employed the same protocol. Each individual test session started with a 30-min baseline period, followed by 45 minutes of RF or sham (no RF) exposure, and concluded with a 10 minute post-exposure baseline period. This sequence was repeated for each subject at three ambient temperatures (Ta) of 24, 28 and 31°C and, at each ambient temperature, at different exposure levels plus sham exposure. In all experiments, the relative humidity was 50 ± 10 %, and the air flowrate in the chamber was 0.35 m/sec. The subjects were seated, with a measured metabolic rate of 1.2 to 1.4 W/kg (compared to a basal metabolic rate of about 0.8 W/kg).
In each study, physiological data (including core and six skin temperatures, metabolic heat production, skin blood flow measured by laser-Doppler flowmetry, and local sweat rate measured by changes in dewpoint temperature) were recorded at several locations on each subject. Measurements subject to modeling included skin temperature in left upper back and central lower back, blood flow measured in the left upper back, and sweating rate measured in the left upper back. The core body temperature was measured in the esophagus at the level of the heart."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC400246/#!po=27.1739
Since the temperatures and the humidity were fixed by the supervisors of the experiment, is it not possible that the experiments took place on the same day under 3 different temperatures and frequencies which were manually adjusted for the chamber?