How can I chmod 777 all subfolders of var?

chmod 777 I'm trying to change the permissions of temp_dir to 777. Why are these commands not accomplishing that? I'm using Linux by the way.. chmod 777 is considered potentially dangerous because you are giving read, write and execute permission on a filedirectory to everyone.

7777 artinya, Setting 777 permissions (chmod 777) to a file or directory means that it will be readable, writable and executable by all users and may pose.