CMAQ v5.5 Annual 2023 Gridded Predictions Across the US and Canada Data contact: Havala Pye, ORCID: 0000-0002-2014-2140 This dataset provides daily predictions of ozone and fine particle (PM2.5) species across the contiguous U.S. and a large fraction of Canada at 12km horizontal resolution for 2023. Values are predicted by CMAQv5.5 with CRACMM chemistry. Please see Pye, H. O. T. (2025). CMAQ v5.5 Annual 2023 Gridded Predictions Across the US and Canada (v1.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.15732714 for the full archive. Please cite the following for CMAQ with CRACMM2: Skipper, T. N., D'Ambro, E. L., Wiser, F. C., McNeill, V. F., Schwantes, R. H., Henderson, B. H., Piletic, I. R., Baublitz, C. B., Bash, J. O., Whitehill, A. R., Valin, L. C., Mouat, A. P., Kaiser, J., Wolfe, G. M., St. Clair, J. M., Hanisco, T. F., Fried, A., Place, B. K., and Pye, H. O. T.: Role of chemical production and depositional losses on formaldehyde in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM), Atmos. Chem. Phys., 24, 12903–12924, https://doi.org/10.5194/acp-24-12903-2024, 2024. DISCLAIMER: This data product has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for public release. At the time of release, the data had not yet been published in peer-reviewed literature. The data is provided for research and the user should verify the data is suitable for their intended use.