This appears to be a vent to the attic. It is located beside a masonry chimney that is being used by a wood burning appliance. There is another vent located beside the wood burning appliance and they may be connected? Anyone seen anything like this before? Thanks.
Combustion air…
I agree…appears to be an attempt to provide additional combustion air to those appliances. If so, it shouldn’t be screened for obvious reasons.
Uhh… right, now it makes so much sense. Thanks 
The screen is to prevent accidental or intentional insertion of insulation or other debris into the vent by the occupants of the home. Perhaps it should be a wider mesh, but a screen is a good idea in my view.
Well, the IRC doesn’t agree with you (M1703.3.4) but if that’s the way you want to report it then it’s A-OK with me. The screen will become clogged with lint, dust (see photo) over time and prevent airflow.