Decays of mesons produced in cosmic ray induced air showers in Earth's atmosphere can lead to a flux of light exotic particles which can be detected in underground experiments. We evaluate the energy spectra of the light neutral mesons π0, η, ρ0, ω,
Nearby in the stack
φ
and
J/ψ
produced in interactions of cosmic ray protons and helium nuclei with air using QCD inspired event generators. Summing up the mesons produced in the individual hadronic interactions of air showers, we obtain the resulting fluxes of undecayed mesons. As an application, we re-consider the case of millicharged particles created in the electromagnetic decay channels of neutral mesons.