Lavender/essential oils in PG

Now I know that they are considered not good in PG but my dilemma is this....

I am currently in the TWW (but snuck a test and have good feelings for a BFP on Thursday)
I walked in to work on Monday and they had lavender oil burning in the oil dispenser REALLY STRONGLY, it left a metalic taste in my mouth all day, I don't want to tell the girls at work that I am PG as I don't even know for sure myself yet and I really want to wait till after the 12week period due to a M/C in Nov 07.

I asked one of my collegues to swap the oil over as it was making me feel ill and giving me a head ache and she put eucalyptus oil in their instead.
I don't know if this is any better, but I did stop feeling sick with it
(they also use lavender oil based airfreshners which was sprayed in my face by a collegue who was trying to be helpful while I was changing a dirty nappy(long day care worker) again with the metallic taste and the smell is in my clothes YUCK!!!

my question is are there any other oils that would be considered a safer alternative that I could provide to my work place for the duration of my "hopeful "PG, as my boss has admitted to me that she doesn't believe the theory about oils being bad in PG and won't stop burning them for that reason.

I know that you shouldn't use Lavender essential oil on your skin before 12 weeks (after is fine) But i am not sure about in an oil burner. But it would be less potent than if it was on your skin anyhow.

Keep away from Peppermint too as that is not good during pregnancy. Same with Rosemary, Sandlewood and Jasmine.

Eucalyptus is fine in pregnancy. Frankincence is also fine.

I hope that helps some. Goodluck, i hope you get your BFP!