Box plot showing the variability in cH₂ concentrations across five point survey days near the DMP Harvey-2 well site in the Perth Basin, Western Australia. The box represents the interquartile range (25th–75th percentile), the line indicates the median, and individual data points are shown to display distribution spread. Measurements were obtained using the GA5000 handheld instrument, which has an upper detection limit of 1000 ppm. Values recorded as 1000 ppm represent the saturation point of the device and should be interpreted as ≥1000 ppm.