One of the somewhat common occurrence that people simply dismiss is the brainfog events. Brainfog is literally a symptom, not an isolated anomaly. This can happen because of poor nutrition or hydration, but this is one of the very common problems that come with a toxic or semi-toxic building.
I have had other air quality responses when I am stuck behind a diesel truck or bus that causes an almost immediate headache. That headache goes away when I am away from the diesel exhaust smell. So, we know the cause of the headache.
This is the classic sick building sign. If the ill-feeling problem comes and goes with some location, you are likely dealing with a sick or toxic building. This is why OSHA and the Department of Labor require that a company use a simple survey by an IAQ Specialist to detect the potential of sick building problems.
In the years when people smoked in bowling alleys, I would get the similar headache in the forefront of the head and a kind of disassociation like brainfog. When I left the bowling alley, the problem would eventually go away.
Unless you have another health reason for the threshold symptoms of brainfog, afternoon headaches, itchy eyes, or bouts of mild nausea; you may be dealing with a polluted building. In particular, if the symptoms dissipate when you get into the fresh air, you are likely impacted by poor indoor air quality.
The good news is the IAQ review is simple and to solution can be quite simple as well. Contact your HR office and ask that they contact the National Air Quality Institute to provide the assistance of an IAQ Specialist.