A common problem of air conditioner filter

Summer arrived the car air conditioning is more frequently, and a good air conditioning filter can you more air filter impurities, while the inferior will may bring you health hazard.
So how to distinguish the stand or fall of air-conditioning filter?
First work, generally good filter with fine making are inferior in general can clearly. Like all five yuan to buy a toy gun and the difference between 50 yuan I believe that everyone still can see. Another is material, general good material is nylon paper + carbon into grey. Because carbon can absorb more impurities, and inferior are only nylon paper or more inferior material
Clean air filter?
Is commonly used time after changing the nylon paper can, because it's main function is to achieve the result of filtering by absorbing impurities