Assertion: air pollution | /r/CreatedBy | other harmful gases
Facets:
value: usually
type: TEMPORAL
Source sentences:
text: Air pollution is a type of environmental pollution that affects the air and is usually caused by smoke or other harmful gases, mainly oxides of carbon, sulphur and nitrogen.
text: Air pollution is a type of environmental pollution that affects the air and is usually caused by smoke or other harmful gases, mainly oxides of carbon , sulphur and nitrogen .