Since they have decided that welding fume is dangerous, it would seem that you have little choice but to reduce it to levels which are as low as is possible. LEV may well be the only method needed, if your worker is bench welding and the fume content is known, and the workshop has no draughts. That would be few workshops. If you welding operation is, for instance, structural steel welding, with long lengths of prepainted steel, with a contractual requirement of unbroken weld runs of long length, then your LEV is unlikely to be sufficient. Ditto for stainless steel welding with hexavalent chromium fume content...fortunately, all welding fume is now considered dangerous