Perhaps you should try some spelling variations:
"5 ppm decrease" » "5 _ decrease" (Expand Search)
"5 non decrease" » "5 _ decrease" (Expand Search), "_ non decrease" (Expand Search), "a non decrease" (Expand Search), "b non decrease" (Expand Search)
"_ e decrease" » "_ _ decrease" (Expand Search), "_ _ decreased" (Expand Search), "_ _ decreases" (Expand Search)
"e a decrease" » "e _ decrease" (Expand Search), "e _ decreased" (Expand Search), "e _ decreases" (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 (((\"_ e decrease\") OR (((\"5 non decrease\") OR (\"e a decrease\"))))))~".
• Removing quotes may allow a broader search: (( 5 ppm decrease ) OR ((( _ e decrease ) OR ((( 5 non decrease ) OR ( e a decrease ))))))~.
• Adding a wildcard symbol may retrieve word variants: (("5 ppm decrease") OR ((("_ e decrease") OR ((("5 non decrease") OR ("e a decrease"))))))*.