Check your owner's manual to see if your car has a cabin air filter. If the answer is yes you may want to make a note to check with your service professional to see if it should be replaced. This is especially true if you suffer from asthma, allergies or live in a dry and dusty environment.
There are two basic types of cabin air filters:
The so-called particulate filter, which is the less-expensive type, is not just for large airborne debris. It traps dust and pollen, two very common allergens that are very small particles, so it has a significant effect on passenger comfort.
The activated charcoal layer/section is added to the particulate filter to absorb order. The manufacturers of the premium filters actually test their products using panels of people with a great sense of smell. Odor control filtration is a complex science involving a lot of trial-and-error. So you should appreciate that an effective filter is a good piece of engineering.
When having your mobile A/C system professionally serviced, insist on proper repair procedures and quality replacement parts. Insist on recovery and recycling so that refrigerant can be reused and not released into the atmosphere.