About: http://webisa.webdatacommons.org/404944433

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Historically, emphasis has been placed on testing for oxygen near mine floors and in low areas to detect gases that are heavier than air, such as carbon dioxide.
http://www.w3.org/ns/prov#wasQuotedFrom	msha.gov