About: part per billion

Head noun: part
Postmodifier: per billion

Same concepts
http://dbpedia.org/resource/Parts-per_notation

Broader concepts

label	provenance	confidence
concentration	isap:41778787	0.338076
level	isap:96033553	0.330121
voc	isap:127736506	0.196162

Narrower concepts

label	provenance	confidence
ozone	isap:202899209	0.276040