Radial oxygen abundance distribution in the Milky Way. Panel a: radial abundance gradients obtained by Arellano-Córdova et al. (2020, 2021). The black circles designate the H II regions from Arellano-Córdova et al. (2020). The dashed black curve is the quadratic fit to those data. The blue squares mark the H II regions from Arellano-Córdova et al. (2021). The solid blue line shows the linear fit to all the data. Panel b: radial abundance distribution in the Milky Way obtained in this work (see text). The black circles denote the H II regions used in the determination of the radial abundance gradient (solid line). The open circles designate the H II regions excluded from the determination of the abundance gradient.