Perhaps you should try some spelling variations:
"dioxide emission" » "dioxide emissions"
"toxic emissions" » "dioxin emissions", "atomic emission", "dioxide emissions"
"oxide emissions" » "dioxide emissions"
"voc emissions" » "bvoc emissions", "voc emission", "vocal emissions"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("toxic emissions") OR ("voc emissions"))) OR ((("dioxide emission") OR ("oxide emissions"))))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"toxic emissions\") or (\"voc emissions\"))) or (((\"dioxide emission\") OR (\"oxide emissions\"))))*".
• Removing quotes may allow a broader search: (((( toxic emissions ) or ( voc emissions ))) or ((( dioxide emission ) OR ( oxide emissions ))))*.