Air circulation is important for controlling humidity and because plants need to breathe just like us.
Air circulation is also great for preventing hot spots, where the direct light on the plant builds up. You want about enough air circulation that your plants leaves gently move as if there was a natural breeze. Too much can actually damage your plant and “wind-burn” it, but the right amount will strengthen the stem which is very important. Also, make sure that you’re both introducing and exhausting the air with fans.