To better characterize how increasing numerical accuracy translates to improvements in large-scale forcing’s over the Northern Hemisphere, two CMAQ simulations with differing grid spacing (108 km versus 36 km) will be compared for the year 2019 using the EPA’s Air QUAlity TimE Series (EQUATES; US (Foley et al. Data Brief 47:109022) modelling platform. When model simulations are evaluated against various surface, aloft, and remote sensing observations, it is found that both simulations produce similar large-scale forcing’s. However, in regions of complex terrain or weather (e.g., dust storms, intrusion events, convection). Some localized differences are seen. But the gains in increasing numerical accuracy must be weighted against the additional computational resources required to simulate with finer grid spacing (e.g., the 36 km simulation required significantly more computational resources than the 108 km simulation). This indicates that the gains in representing large-scale air pollution forcing through improvements in numerical accuracy via grid spacing improvements may not outweigh the computational cost.