Many vehicles on the road today make use of cabin filters as a part of the air-conditioning and heating system. This filter is usually found under the dash inside the vehicle, or under the hood near the firewall. It is effective in eliminating dust and allergens from the air before they reach your nose and eyes, but it also protects vital components of your heating and air-conditioning system from damage.
The cabin filter is a smaller, denser version of the intake air filter in a vehicle. The filter is made of paper housed in a plastic form, and is specific to each vehicle by make, model and year. It is attached to the air-conditioning and heating systems, and is the last line of defense for preventing unwanted dust, allergens and particulate matter from entering the interior (cabin) of the vehicle.
Your vehicle's heating and cooling system works on the same principles as home heating and cooling systems. Outside air is drawn into the system to be heated or cooled, depending on the settings you choose, and passes through filters designed for drying and cleaning the air. In your vehicle the last filter the air passes through is the cabin filter. What comes out, inside the vehicle through vents, is very clean and nearly free of allergens.
Prior to the advent of the cabin air filter, a lot of the dirt, dust and allergens from outside came inside the vehicle through the vents. This often left the vehicle's interior, and sometimes the passengers, coated in a fine layer of dust and dirt. The cabin filter changed all that, and today many vehicles have cleaner air than ever before.
A dirty cabin filter is not only inefficient, but will restrict airflow into the cabin of your vehicle. This restriction in airflow means other components in your air-conditioning and heating system will have to work harder. Over time this will cause failure of some of these components, possibly resulting in costly repairs. The cabin filter is a recent addition to the automotive industry so this filter is quite often overlooked during routine maintenance and inspections. Sometimes the first indication you have of trouble is a reduction in airflow through the ventilation system in your vehicle. Changing your cabin filter is a job that can be accomplished by moderately experienced do-it-yourself enthusiasts or by any qualified mechanic.
Aircraft manufacturers have used cabin filters to clean the air inside aircraft for a number of years. Modified cabin filters are also found on the space shuttle and space station. Though much more complex than the ones used in Earth-bound vehicles, these filters provide everyone from airline passengers to astronauts with clean, fresh, breathable air in places where the environment is less than ideal.
