A four floor high building

Question

There is a four floor high building owned by a company:

The first floor

A small office, where the employees are divided in teams of two.
Each teams does the same work, and help each other for everything.
Each team consists of similar number of people of the similar type who do a similar job.
But often the two teams usually end up facing each other.
They work very hard and are an essential part of the building.

The second floor

The second floor is the only place in the building where there are big open windows for ventillation.
It is dirty but the people need this. Without it, the office would have no ventillation and thus the people would suffocate. It is always open, but then it gets blocked every once in a while. The people clean it THEN.

The third floor

In the third floor, there are AGAIN windows. But these windows are fastened shut. They can't be opened, even if you do anything. Though, the view from here is amazing.

The fourth and the final floor

The fourth floor is the last and the strangest of all the floors. The company grows various types of plants here, mainly grass. Only plants. No animals. They kill animals if they ever see one.
And the strangest thing of all is that this company colours their plant. Literally colours them. Their prefered colour is black, but then every colour gets the chance once in a while. Strange!

HINT:

No. No hints.

What is this company and what are the floors?

P.S. These floors can be solved independently

Answer 1

My personal guess is this company is the

human head

First floor

Teams of two opposing teeth. Each upper (and lower) set is divided into equal sizes teams of incisors, canines, molars and pre-molars. They do work hard biting and chewing. At rest they face each other.

Second floor

These are the nostrils which are crucial for ventilation. They contain mucus, which may be deemed dirty, but cleans the nose lining and warms the air we breathe. When a blockage appears, blow your nose.

Third floor

The eyes - don't see through them due to the retina (optic nerves carry signals one way). The view are the images we see.

Fourth floor

Hair as it grows like a plant without moving location. If lice or other insects are there, get rid of them. The majority of humans have black hair, which may go white, but there are other colours.