[Ar II]/[Ne II] as a function of [Ne II] luminosity for the five regions in FLS1 (red) compared to local star-forming galaxies (gray). FLS1 is broadly in line with typical star-forming galaxies, although most of the points falls on the upper envelope of local [Ar II]/[Ne II] ratios. The comparison objects are drawn from the limited and heterogeneous sample of objects with published JWST, Spitzer IRS, and ISO measurements for the necessary lines. In most of the comparison galaxies, the spectral aperture includes only the central region of the object. Since this heterogeneous literature sample has not been corrected for extinction, we have plotted our uncorrected line ratios. Using the optical depths we found in Section 3.2 would result in a 20% decrease in the [Ar II]/[Ne II] ratio. Measurements are taken from Förster Schreiber et al. (2001), Verma et al. (2003), Armus et al. (2006), Egami et al. (2006), Gallimore et al. (2010), Sales et al. (2010), Armus et al. (2023), Goold et al. (2023), Gallimore et al. (2010), and Sales et al. (2010).