I was overwhelmed looking at all of the available a/c filters when I was at our local hardware store last week. Once I had determined the size of our filter tray, which in our case is 20 by 20 inches, I finally had to choose a brand plus style of filter. But since this was our first time owning our own locale plus having to finally buy an Heating plus Air Conditioning filter myself for the first time, I was confused plus unsure of what to buy. I asked the heating plus cooling expert at the hardware store plus he told me that the basic differences between filters is in the level of absorption they have of air contaminants like dust, pollen, plus mold spores. Your most basic filters can only handle dust plus pollen while some of the most high-priced filters are dense plus thick enough to filter out actual bacterial plus viral pathogens on top of a whole host of varying particles that can theoretically swirl through the air in your home. I noticed some filters plus whole-condo air purifiers in the store flaunted with something called HEPA certification. He said that this stands for high efficiency particulate air/absorption, plus that essentially these filters have an ability to filter our air particles at a level far beyond that of most regular filters. And anything sold as a “HEPA filter” undoubtedly has to meet regulatory standards set forth by a collective of varying governing bodies plus entities, so if you buy a single you suppose you’re getting a guaranteed product. Hospitals use them, nursing homes use them, plus people with asthma plus dust sensitivities are encouraged to use them as well. I have issues with both from time to time so I figured I’d supply the HEPA filter a shot despite the price, plus boy am I thrilled I did. My breathing feels more seamless plus less constrained plus I haven’t had a headache since I put it in. It pays to get the right kind of filter for whatever your needs are.