Most Hwuru have a mild dependence on chaoofsh a chemical attractant released by the trees native to their world. When off-world, they tend to wear a breathing apparatus to deliver this chemical.
Chaoofsh Dependence
Virtually all (85%) of Hwuru are physically dependence on chaoofsh (an inhaled intoxicant). Going with-out for 12 hours or more leads to withdrawal: Toxicity 8, Interval one day, Virulence 3. Each failed save means a -1 to Intelligence, Wisdom, and Dexterity. Withdrawal resolves in 5 days.