@bakeandfry wrote:

Pdf files are harmfull to mobile devices.

Technically, they have the potential to harm any device, since they can contain things other than just images and text (eg scripts, even executable files, though their security has improved and most readers will now block them from automatically doing anything that can hurt a device - Adobe has a reader for mobiles, I don't know too much about it because I don't have anything that could run it, but if it's a security risk that's the cause of concern, it's probably worth checking out some of the mobile readers and seeing what level of protection they offer - the PC version of Adobe allows PDFs to be opened in a protected mode, at least).