Assertion: methane's concentration | /r/HasProperty | toxic
Facets:
value: over longer exposures
type: TEMPORAL
value: potentially
type: DEGREE
Source sentences:
text: At concentrations greater than 2,000 ppm (0.2%) it is generally quite noticeable, however lower concentrations may remain undetected while still being potentially toxic over longer exposures, and may still present a fire/explosion hazard.