Large angular radio loops, such as Loop I and the North Polar Spur, are vast synchrotron-emitting structures in our Galaxy that dominate low-frequency sky maps and contribute significantly to polarized foregrounds used in CMB analysis (Berkhuijsen et al. 1971; Planck Collaboration 2016). ΛCDM itself is agnostic about such Galactic features, but cosmological inference becomes tense because uncertainties in loop distances, shapes, and spectra translate into poorly modeled foregrounds, complicating the separation of faint primordial CMB signals—especially B-modes—from bright synchrotron emission and potentially biasing tests of inflation and isotropy (Mertsch & Sarkar 2013; Vidal et al. 2015).