Night sky radiation measurements have been carried out in June in Athens. Computations of the correlations with the most common type of equations used for sky radiation are performed. Brunt, Brutsaert and Idso type of equations fit well with experimental data. In terms of the zero intercept, equations (of polynomial type) correlating the sixth power of the screen level air temperature and the square of vapour pressure show better behaviour. City pollutants do influence the sky radiation. The equation that best fits to the experimental data is of polynomial type and includes the square of the sum of the partial pressures of four city pollutants as well as the sixth power of screen level air temperature and the square power of vapour pressure.