Different inorganic materials were evaluated as substitutes for air, in photon radiation environments. The materials were evaluated based on their: total mass attenuation coefficients, mass-energy absorption coefficients, total electron mass stopping powers. Common inorganic compounds and mixtures not containing carbon were theoretically tested with the aim to find a solid or liquid air substitute material for photon radiation. As presented in this work, the best results of these tests were achieved for liquid nitric acid diluted in water at 81 wt%. This solution exhibits hitherto unknown properties similar to air for photon radiation in the energy region 0.1 to 1000 MeV and can be used for air photoactivation determination as well. The inherent property of this aqueous solution is that it allows simultaneous determination of all photonuclear reaction yields from nitrogen and oxygen in a wide range of photon energies. Additionally, this aqueous solution does not contain any other constituent elements, which could affect the accuracy of this determination.