What are the types of filters for air purification?

The first, and most important type, would be a HEPA filter. They are pretty much the standard filter. HEPA stands for High Energy Particulate Air Filtration. This was a medium that was developed by the US government during World War II. They used it to prevent radioactive particles from escaping from labs. These substances are made out of silicate, which is very glass-like, and this silicate is formed into sheets that are thin enough and effective enough to increase the surface area for filtration. So HEPA filters are simple mechanical filters that remove particulates from the air very effectively. They'll remove 99.9% of particles that are 0.3 microns or larger from the air. That pretty much covers everything. You can expand on that by using HEPA with activated carbon. Carbon is really nothing more than charcoal. It's made from nutshells, coconut husks, and things like that. The most important thing with carbon is that 5 gm of high quality carbon has an absorptive surface area greater than a football field. If you think about a HEPA filter with carbon, you have an amazing filtering ability. You not only filter out the contaminants, but you also contain them. So that would be one broad category.

There is another category. This would be an ozone generator. There are two schools of thought on ozone generators. The theory is that ozone purification converts chemicals in the air into other harmless substances, and a lot of researchers have shown us that this is not really the case. Studies recommend that you do not use ozone generating appliances in the home because it can have a damaging effect on health, especially for persons with asthma and other lung diseases. When you inhale it, ozone can cause respiratory problems in older people, children, and even healthy adults. It has been shown that long-term exposure can lead to premature aging of lungs and chronic respiratory conditions. So, it's a very difficult topic. There are two very opposing thoughts about this product. Our opinion here is that it is not healthy, and it is not a good thing to be using.

Another type of purifier that you've probably seen is an ion purifier. These generate negative ions. They strip them into the room's air, and they create a static charge, which causes these particles in the air to be attracted to surfaces. These would be table cloths, walls, and things like that. It removes them directly from the air, but it doesn't remove them from the room. It also creates ozone. The concern with a product like that is that the same electrical charge could also attract those materials to the lung tissue of anybody in the room. And so, once again, that is not a good thing.