Composite image of OH 231.8+4.2 displaying: (grey scale) the dust distribution as observed with HST/WFPC2 and the broad-band F791W filter (Bujarrabal et al., 2002); (contours) the molecular outflow as traced by the ¹²CO (2–1) emission (velocity integrated) mapped with 1.̋5 × 0.̋7-resolution (see Fig. 4 in Alcolea et al., 2001). The dashed circles show the area covered by the largest and smallest telescope beams (HPBW) of the IRAM-30 m observations presented in this work. The different emitting clumps, I1-I7, are labelled as in Alcolea et al. (2001). The V_LSR range (in km s^-1) of each clump is I1) [−80:−30], I2) [−30:+10], I3) [+10:+55], I4) [+55:+80], I5) [+80:+150], I6a) [+150:+205], I6b) [+205:+230], and I7) [+230:+285] (see Table 2 in Alcolea et al., 2001, for more details on the physical properies of the clumps).