Imagine that you are in a cubicle located in the middle of the office floor plate. Your office has a glazed front, but you are looking into another open office. You have no real window or view to the outside, so you can't tell if it's raining outside or sunny. If you are lucky, and you do have a window, it's fixed, and you are looking into an office in the neighbouring building that is five metres away.
The fluorescent lighting that you sit under for eight hours has thrown out your body's natural circadian rhythm. The ventilation is alright, but you start to feel droopy at around 3pm because the carbon dioxide levels in your shoebox have risen. It might even feel a bit stuffy, regardless of the door being open or closed. As you don't have an operable window, you have been breathing in recycled air all day. When you get outside and take a breath, you will instantly notice that the air outside is fresh.
Now multiply that by five days a week, 48 weeks a year. Maybe you will get a pot plant in a few weeks.