The search for functional polymers for an optical chemical sensor (OCS) for sulfur dioxide was continued. Copolymers of polyamides, methyl methacrylate (PMMA), and poly(dimethylsiloxanes) (PDMSs) were examined. It was shown that the sensitivity of the spectral parameters of polymers in absorption spectra of their films upon the action of SO2 in vacuum depends on the chemical and phase composition of polymers. For a sensor with a sensing layer based on PDMSs, linear calibration graphs on logarithmic coordinates were obtained in a wide range of SO2 concentrations in an air flow (5–6200 mg/m3). It was found that the slope of the calibration graph depends on the thickness of the sensing layer, other conditions being the same. The calculated detection limit is of about 3 mg/m3, which points to the possibility of using the proposed OCS for controlling the air of the working area.