This feature wasn't standard on Toyota 4Runners until the 2003 model year.
If you're looking to improve air quality in your 4Runner, you can either:
* Install an aftermarket cabin air filter. Several companies offer these filters, and you can find them online or at auto parts stores.
* Use a cabin air filter replacement kit. These kits typically come with a new filter and instructions on how to install it.
Before installing an aftermarket filter, be sure to check your owner's manual or consult a qualified mechanic to ensure proper installation and compatibility.