Here's the written version with added details...
This Is Bad For Your Health. Here's Why:
#1 Dust, hair, pollen, animal dander = allergies, asthma, odors
#2 Chemicals, vapors = odors, chemical sensitivity, immune system stress
#3 Mold, mildew, bacteria, germs, viruses = immune system (colds, flu, viruses), and odors.
#1 HEPA, Pre-filter, Neg/Ion, and Plasma Grid = Helpful for allergies and asthma, some odors
#2 Carbon, Charcoal, Ozone, and Zeolite = Helpful for odors, smoke, animal smells, chemical sensitivity, and protecting our immune system
#3 UV, TiO2, Plasma Grid, and Ceramic = Helpful for immune system protection (colds, flu, viruses, pathogens), and eliminating musty odors.
(In Chronological order)
1. Charcoal Filters (1854) - Absorbs odor and some gases.
Pros: Good for smoke, pet odor, and hazardous fumes. Inexpensive.
2. Ozone (O2) (1881) - Ozone is what you might smell in the air after a thunderstorm. It's oxygen with an extra charged particle attached which is unstable and only lasts a second but does a great job on odor, mold, etc.
Pros: It kills odors better than anything else. Kills mildew and mold. Good for chemical removal as well. (I love a little Ozone which I turn on a few hours before bed to make the room really fresh and clean).
Cons: In small amounts (low level) it is safe and very effective. (Consumer Reports blasted Sharper Image/Ionic Breeze because their unit put out very high levels of Ozone. As a result unfortunately many people are now afraid of ozone).
Note: Because of Sharper Image Manufacturers are now either 1) avoiding Ozone 2) calling it "Activated Oxygen" 3) putting timers on Ozone.
3. HEPA (1934) - HEPA air purifier filters trap up to 99.97% of dust, pollen, dander, etc. Many manufacturers however leave it out because of the manufacturing expense.
Pros: Very helpful for allergies, dog/cat hair, pollen etc. A must for asthmatics.
Cons: HEPA air purifier filters have to be replaced, but they work very well. Replacement filters are typically overpriced (like printer cartridges) so look for a Purifier Brand whose replacement costs are reasonable (maybe $20-40 depending on the size/thickness).
4. UV Light (1936) - UV light kills many pathogens such as mold, viruses, germs and bacteria. (Used in hospitals).
Pros: with today's pathogens and bacteria strains UV is a great addition - especially if you have children, asthma, or immune challenges.
Cons: You have to replace the bulb(s) every year or so. Like with HEPA make sure the Manufacturer isn't "soaking" you for high replacement costs. Don't pay more than $20-30 for a bulb.
5. Negative Ion (1974)- Negative Ion is a positive thing for removing some pollen, smog, and some dust. The early ionizers would make your walls black because the charged dirt would adhere to the walls around the unit. That's now taken care of by grid plates.
Pros: Very affordable method for cleaning the air.
Cons: It works well in combination with other technologies but it's not very effective by itself.
6. Ceramic - Uses heat inside a chamber to kill pathogens in the air as air is drawn into and thru the chamber. (This is also how a fever works in our body, raising the temperature to kill a virus).
Pros: Heat kills pathogens.
Cons: Most experts believe UV does a better job, with a lot less electricity. You don't see many of these filters for that reason.
7. Washable Pre-Filters - This basically catches hair and large airborne particles. Most purifiers have these.
Pros: Very inexpensive addition by manufacturers. . It also extends the life of the other filters.
8. Ti02 Photo-Catalytic (1991) - Enhances the UV light up to 4000% to kill germs, viruses, mold, bacteria, as it passes through the filter.
Pros: What's great is now the UV bulb doesn't have to be as strong or as big yet works more effectively. Cons: None.
9. Plasma Dust (or Grid) Filters (1989) - Uses a charged grid plate to shower the incoming air with both positive and negative ions. Removes some airborne particles and some micro-organisms. I wouldn't count on this alone but it will do some cleaning as you'll see when the plates get dirty. It's basically an ionizer on steroids. The "Never needs a replacement filter" types (Ionic Breeze, Oreck) fall into this category. (Note: You never need a replacement filter because your lungs are filtering what it doesn't do a good job on)
Pros: You can wash it.
Cons: Works well, but needs other technologies to do a good job.
#10 New Air Technology From Japan: Pollen, Odor, Dust Sensors I think this is very cool and very useful.The Japanese have developed sensors that detect pollen, odor, and dust in the air.
Pros: Saves electricity and guesswork as you can leave the unit on "Auto" all the time. I think it's the greatest thing for allergy and asthma prevention. The sensors turn the technologies on/off /low/high depending on the needs of the room.