The abbreviation etc. stands for the Latin et cetera, which means “and other things”. The abbreviation is used to indicate that a given list is not comprehensive. The word is usually followed by a full stop, but note that if etc. ends a sentence, only one full stop is used.

We included several characteristics about the measuring sites (whether they were urban, rural, etc.) in our data.

Monitored pollution types included particulate matter, gases, etc. We also collected information from the factories themselves.