We report observations of carbon recombination lines near 34.5 MHz ( n \sim 578 ) and 325 MHz ( n \sim 272 ) made towards Cas A , the Galactic centre and about ten other directions in the galactic plane .
Constraints on the physical conditions in the line forming regions are derived from these and other existing observations .
The CII regions that produce the low-frequency lines are most likely associated with the neutral HI component of the ISM .