Assertion: smog | /r/HasProperty | serious problem
Facets:
value: in most big urban areas
type: LOCATION
value: in many cities
type: LOCATION
Source sentences:
text: Smog is a serious problem in many cities and continues to harm human health.
text: Smog is a serious problem in most big urban areas.
text: Smog is a serious problem facing America today, and one that effects all of us.
text: Smog is a serious problem that poses risk to human health and the environment.