The Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) is a newly developed chemical mechanism that integrates reaction pathways for formation of ozone, secondary organic aerosol, and hazardous air pollutants. To extend the applicability of CRACMM to broader spatial and temporal scales, we implement halogen reactions into CRACMMv2. Since recent studies suggest that the photolysis of particulate nitrate can produce gaseous nitrous acid and nitrogen dioxide, we also implement the photolysis of particulate nitrate into CRACMMv2. Three different simulations are performed for May 2018 using the Community Multiscale Air Quality (CMAQv5.5) model over the Northern Hemisphere with 108-km horizontal grid spacing. The first simulation uses the CRACMMv2 without halogen chemistry and particulate nitrate photolysis. The second simulation uses CRACMMv2 augmented with halogen chemistry, and the third simulation uses CRACMMv2 with both halogen chemistry and the particulate nitrate photolysis. The halogen chemistry reduces monthly mean ozone by 3.6 ppbv over the entire seawater and 2.2 ppbv over the entire land. In contrast, the photolysis of particulate nitrate compensates the halogen mediated ozone loss by enhancing the mean ozone by 6.5 ppbv over the seawater and 6.5 ppbv over the entire land. We compare model ozone with measurements from the Air Quality System (AQS) sites over the U.S. Over the eastern U.S., the monthly mean bias of the model without the halogen chemistry is − 0.8 ppbv, the halogen chemistry deteriorates it to − 2.9 ppbv, and the particulate nitrate photolysis increases it to + 2.5 ppbv. Over the western U.S., the monthly mean bias of the model without the halogen chemistry is − 6.6 ppbv, the halogen chemistry deteriorates it to − 9.6 ppbv, and the particulate nitrate photolysis improves it to + 1.4 ppbv.