This manuscript proposes a Madelung-type multifractal model for atmospheric pollutant dynamics. The formulation preserves the conservative advection-diffusion-reaction-deposition structure used in classical air-quality modelling, while adding a weak, regularized curvature-sensitive correction intended to represent unresolved intermittency, plume focusing, concentration localization, and heterogeneity-driven accumulation. The model defines the atmospheric domain, pollutant concentration vector, atmospheric burden, effective transport velocity, anisotropic turbulent diffusivity, boundary-layer mixing, sectoral emissions, wet scavenging, dry deposition, gravitational settling, reduced chemical transformations, aerosol diagnostics, and observation operators for calibration and validation. A heterogeneity index is introduced to account for orographic confinement, surface roughness, land-use structure, boundary-layer stability, and humidity or heat-island effects. The multifractal contribution is formulated through a regularized concentration amplitude, a curvature-sensitive potential, a mobility-controlled drift, and a bounded diffusivity correction, so that the additional term modifies but does not replace the classical transport core. An illustrative synthetic simulation demonstrates numerical implementability, plume migration under imposed wind, localized accumulation near emission gradients, and exploratory scale-sensitive diagnostics. The proposed framework is therefore best interpreted as a physically constrained modelling extension that requires calibration and independent validation with meteorological, emissions, station, and remote-sensing data before operational use.