Perhaps you should try some spelling variations:
lipid environment » grid environment, arid environment, wind environment
covid environment » cold environment, closed environment, cloud environment
policy paper » policy part

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: ((lipid environment) OR (covid environment)) policy paper.
• Adding a wildcard symbol may retrieve word variants: ((lipid environment) or (covid environment)) policy paper*.