In the page of 'overpower' in encyclopedia.com, there's such a sentence as follows.
They were overpowered by the fumes.
The explanation of 'overpower' in that sentence given by encyclopedia.com is
be too intense for; overwhelm.
However, I don't quite get what that sentence exactly means. I wonder if the people in that sentence passed out due to the fumes or their actions were restricted by the fumes, or something else.