Perhaps you should try some spelling variations:
"5 ppm decrease" » "5 _ decrease" (Expand Search)
"_ nn decrease" » "_ _ decrease" (Expand Search), "_ ann decrease" (Expand Search), "_ cnn decrease" (Expand Search), "_ knn decrease" (Expand Search)
"5 we decrease" » "5 _ decrease" (Expand Search), "_ we decrease" (Expand Search)
"5 c decrease" » "5 _ decrease" (Expand Search), "5 _ decreased" (Expand Search), "5 _ decreases" (Expand Search), "45 c decrease" (Expand Search)

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"5 ppm decrease\") OR (((\"_ nn decrease\") OR (((\"5 c decrease\") OR (\"5 we decrease\"))))))~".
• Removing quotes may allow a broader search: (( 5 ppm decrease ) OR ((( _ nn decrease ) OR ((( 5 c decrease ) OR ( 5 we decrease ))))))~.
• Adding a wildcard symbol may retrieve word variants: (("5 ppm decrease") OR ((("_ nn decrease") OR ((("5 c decrease") OR ("5 we decrease"))))))*.