id	keyword
21907	black
21907	lungs
21907	coal
21907	disease
21907	matter
21907	carbon
21907	fluid
21907	pulmonary
21907	chest
21907	air
21907	case
21907	bronchial
21907	cough
21907	blood
21907	years
21907	time
21907	substance
21907	glands
21907	lobe
21907	dark