I have seen during homa/fire sacrifices air is blown by using fan (handheld fans/plates/etc.). I was always told that blowing through mouth is impure (because may be saliva dropping on fire).
However, I came across a book (in Tamil; screenshot attached) which quotes Devala and says one must not use fans (handheld fans, plates, etc.)...the book recommends using blow air from mouth through a tube.
This book does not mention which scripture this quote from Devala is. So, question is, a) what are the rules regarding fanning sacred fire? b) Is blowing air through mouth is allowed?
