A very helpful aricle here.
Camphor essential oil is derived from Cinnamomum Camphora from China and Taiwan.
Cinnamomum camphora ct linalool from Fujian China is used to make Ho Leaf essential oil which contains 90%+ linalool rather than cineole, camphor or estragole.
So if you reach for the cinnamon camphora from china expecting cineole to relieve a blocked nose you could be relaxed but disappointed. Ravintsara essential oil from cinnamomum camphora grown in madagascor contains little camphor and little linalool. Cineole is a major component of Ravintsara.
Madagascor is the worlds third largest island and contains a treasure trove of aromatic plants and trees.
From Madagascor comes two oils. Ravensara aromatica has a different chemistry to Cinnamomum camphora ct 1,8-cineole. Methyl chavicol (estragole) is the major component of Ravensara which finds use in the treatment of shingles. Estragole is a suspected carcinogen. Limiting use with children or pregnant or nursing mothers seems appropriate. Also, true Ravensara aromatica can be a skin irritant.