The engine air filter stops airborne contaminants from getting sucked into your vehicles' engine before it can do damage to the engine.
Your engine will run rich (too much gas and not enough air) if your engine is not able to suck enough air into the combustion chambers due to it being too dirty or clogged. When that happens, your vehicle could lose power and the engine will not run smoothly. Also, your “Check Engine” warning light may come on. When this happens, stop by your local Take 5 located at 3930 Fairmont Pkwy, to have a certified Take 5 technican inspect the filter.
Your vehicle may stop running altogether if you really neglect the air filter for a long time. Permanent damage is unlikely, but it is possible. Sufficiently dirty or damaged air filters would allow harmful, abrasive contaminants into the combustion chamber.