Abundance gradients of neon, sulphur, and argon in the Milky Way. The dashed lines represent the oxygen abundance gradient from within the Galactic disk with a slope of −0.085 dex/kpc (Pottasch & Bernard-Salas 2006), passing through the solar value at 8.0 kpc (Asplund et al. 2005). The solid lines represent the line of best fit in each plot, with gradients of −0.058 ± 0.021, −0.079 ± 0.012 and −0.062 ± 0.023 dex/kpc respectively.