A portable apparatus and method for discharge of CO.sub.2 snow or a combination of CO.sub.2 and ice along a generally horizontal path over and onto a load within an elongated insulated container from one partially open end of the container toward the other closed end thereof and in a manner to form either a blanket of CO.sub.2 snow or a blanket of ice over the load within the container. The apparatus includes a rectangular or cylindrical duct into which liquid CO.sub.2 is discharged adjacent one closed end for impact against the walls of the duct before exiting in a CO.sub.2 snow and gas stream from the opposite open end. A transverse manifold is mounted adjacent the open end to jet spray water feed to the manifold into contact with the CO.sub.2 stream at an acute angle, preferably about 15.degree..