Oxygen diffusion in atactic poly(methyl methacrylate) has been studied by anthracene luminescence quenching in geminate pairs anthracene-oxygen at 77-130 K. Analysis of the experimental data shows that the luminescence quenching is well accounted for by a polychromatic model assuming a log-normal diffusion coefficients distribution due to inhomogeneity of polymer structure. Energy activation is equal to 30 +/- 1 KJ/mol. All diffusion coefficients data in the range 77-300 K demonstrate a good linear Arrhenius law.