The emission of helium neutrals recycling on a poloidal limiter is analysed, so as to combine passive spectroscopy with the He I line intensity ratio method, widely used in combination with atomic helium beams in fusion devices, to measure the plasma electron temperature T_e and density n_e. The inherent problem of passive spectroscopy, in contrast to active spectroscopy, is that the measured intensities result from the integration of the emission over the whole line of view. Local information is therefore difficult to obtain. Here, however, it is demonstrated that this problem can be overcome by choosing the correct observing geometry that integrates the dominant plasma emission over nearly constant T_e and n_e chords in front of a poloidal limiter. In this paper only radial electron temperature profiles are deduced from two He I lines, although n_e measurements using a different He I line pair is also possible. The experimental results are in good agreement with other diagnostics. A future possibility of this method could be two-dimensional imaging of T_e and n_e in the plasma boundary with good temporal resolution. The combination of passive spectroscopy and the He I line intensity ratio technique would be especially attractive in reactor-relevant conditions, where helium will be naturally present in the plasma.