White Sage (aka California Coastal Sage, Giant Sage) is a highly medicinal plant. It is the #1 item for smudging and is said to be excellent for purifying and driving away "things".

My main use for it has been if I get a runny nose. I make up a pot of strong sage tea and drink it a cup now and then during the day. It doesn't taste very good but it sure does keep you dry, and with no bad side effects.

I don't think you can get high off of the smoke, but then I haven't been intensely exposed to the smoke - most smudging ceremonies I've participated in have been in relatively drafty environs (yurts and tepees). I doubt it used up much of your O2 though.

As a comparison of power, last time I got a badly runny nose I was out of white sage and brewed up several strong pots of my fresh garden sage. I drank lots and lots of it and it had no effect whatever (but it tasted better than white sage).

The best way to find out how much is enough is to try too much.

I do this a lot in cooking but try to go real easy on how much too much to try

. . by visiting dignitaries from the plains states and other inland regions.

The general procedure here is to pull some hot coals from the fire (with your fingers if you've got the balls, muscular coordination and experience to know where to grab them) and place them in a large abalone shell. The sage is then piled over and fanned with a hawk wing or whatever you have. The smoke is spread about the premises accompanied by prayers, chanting, drumming or whatever combination works for you.

Of course large abalone shells are hard to get in most places and hawk wings are illegal except for Indians** - and even then are supposed to be certified as natural kill (power line maintenance crews sometimes find freshly killed eagles and hawks and turn them over to local tribes). All is not lost because other natural items can be used.

Note that sweet grass, native to both North America and Eurasia (north of Switzerland), was used on the doorsteps of European churches long before the discovery of America.

** Indians. I've dropped the "Native American" tag on advice. When the film Pocahontas was being made the crew employed a well known cultural figure as a consultant. When asked if they were doing anything that would be particularly offensive to his community he answered, "No, except stop calling us 'Native Americans'. We're Indians". My source here is an interview on KUSC of the guy who wrote the score for the film.