  We calculate the density shift and broadening of selected dipole transition
lines of pionic helium in gaseous helium at low temperatures up to T=12 K and
pressure up to a few bar. In the approximation of binary collisions the shift
and broadening depend linearly on the density; we evaluate the slope of this
linear dependence for a few spectral lines of known experimental interest, and
also investigate its temperature dependence. We find a blue shift of the
resonance frequencies of the $(n,l)=(16,15) \rightarrow (16,14)$, $(17,16)
\rightarrow (17,15)$, and $(16,15)\rightarrow(17,14)$ unfavored transitions,
and a red shift for the favored one $(17,16) \rightarrow (16,15)$. The results
are intended to significantly increase the efficiency of the laser spectroscopy
investigations of pionic helium and help the interpretation of the experimental
data.
