Why HEPA air filter need periodic replacement?
HEPA air filters need replacement at some point. This is for the sake of ensuring you are getting a high level of air cleaning. As the filters collect particles like pet dander, mold spores, pollen, and other airborne allergens, the airflow resistance will increase.
This results in less airflow through the filter and lower air cleaning performance. If the filter is clogged, it will have a difficult time in moving the air to clean your room.
Safety is also best. HEPA filters only use mechanical filtration. They do not generate any unwanted air pollutants such as ozone. If you are looking for a recommendation, consider the Agcen KJ750F-T02 HEPA air purifier. It is an air purifier that works for 90 sq. meters room and sterilizing rate 99.99% max.
Learn more about HEPA air filter: http://en.agcen.com/products_detail/productId=43.html