Surface mass density of hydrogen atoms converted from the reddening maps of Green et al. (2019; top left) and Leike et al. (2022; top right). Surface mass density of hydrogen atoms reconstructed from HI4PI data using the BEG03 and SBM15 gas flow models (middle left and right panels respectively). Surface mass density of hydrogen atoms reconstructed by Nakanishi & Sofue (2016; bottom panel). The Galactic spiral structure fitted from data of molecular masers as in Reid et al. (2019) is also overlaid on all the plots. The red (blue) ellipses mark some representative regions in which structures from our gas maps are seen (are not seen) in the dust maps.