Poly(styrene-acrylonitrile) (SAN) and acrylonitrile-[ethylene-propylene diene monomer (EPDM)]-styrene (AES) films were exposed to long-wavelength radiations (A > 300 nm) in the presence of atmospheric oxygen. Fourier transform infrared (b-T-IR) and Fourier transform Raman (FT-Raman) spectroscopy were used to follow the chemical evolution of the polymer. The different photoproducts formed were identified by coupling FT-IR analysis to chemical derivatization reactions. The contribution of styrene, acrylonitrile and EPDM to the general mechanism of degradation was determined, showing that the presence of EPDM enhanced the chemical evolution of the other components, compared to the homopolymers polyacrylonitrile and polystyrene, both studied previously. The distribution of the photoproducts profile within thick samples was also determined.