sentences: if something metric something else then that something else pollution from that something
docs: second_messenger is tangible_thing. fault is tangible_thing. goods is tangible_thing. volatile_memory is tangible_thing. protein_molecule is tangible_thing. covering is tangible_thing. pollutant is tangible_thing. etcher is tangible_thing. dangerous_thing is tangible_thing. semiconductor is tangible_thing.