Starting with the basics: Air purification 101
When compressed air heats up it becomes "dirty", resulting in the system omitting too much moisture or oil into the air which can cause havoc to your equipment and air quality-particularly in lab and hospital environments that require high quality "medical air or for electronic assembly environments that requiring dry "shop air". This is true for numerous industrial applications as well.
As such, it's important to remove the moisture and contaminates to ensure an optimal air quality environment. This involves equipment such as compressed air dryers, filtration, condensate management systems and air quality monitors.