Perhaps you should try some spelling variations:
"50 ppm decrease" » "50 _ decrease" (Expand Search), "50 pa decreased" (Expand Search), "50 026 decrease" (Expand Search), "5 ppm decrease" (Expand Search)
"50 nn decrease" » "50 _ decrease" (Expand Search), "50 mean decrease" (Expand Search), "50 gy decreased" (Expand Search), "50 ns decrease" (Expand Search), "50 ng decrease" (Expand Search), "50 n decrease" (Expand Search)
"5 we decrease" » "5 _ decrease" (Expand Search), "5 mean decrease" (Expand Search), "5 teer decrease" (Expand Search), "_ we decrease" (Expand Search), "5 wt decrease" (Expand Search), "5 w decrease" (Expand Search)
"5 a decrease" » "5 _ decrease" (Expand Search), "5 _ decreased" (Expand Search), "5 _ 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: "((\"50 ppm decrease\") OR (((\"50 nn decrease\") OR (((\"5 a decrease\") OR (\"5 we decrease\"))))))~".
• Removing quotes may allow a broader search: (( 50 ppm decrease ) OR ((( 50 nn decrease ) OR ((( 5 a decrease ) OR ( 5 we decrease ))))))~.
• Adding a wildcard symbol may retrieve word variants: (("50 ppm decrease") OR ((("50 nn decrease") OR ((("5 a decrease") OR ("5 we decrease"))))))*.