A common theory states that indoor air quality can be greatly improved by electrically charging the air. Air is accelerated over charged plates, imparting a charge to the air, which reportedly improves mood, causes bacteria, viruses, and dust to adhere to surfaces instead of becoming airborne, causes beneficial effects on the health of the people who breathe it, and even helps heal injuries. Some or all of these claims might be complete hogwash. One thing is definitely clear, though. Air ionizers create ozone, an oxygen variant that damages your lungs and is the major component in smog, although more useful in the upper atmosphere due it its tendency to neutralize harmful radiation.
The best evidence for the touted benefits of the theory was a study conducted in Bangkok, which showed that ionized air did improve rates of healing from injuries, and did in fact cause airborne bacteria to cease to be airborne, where it could be easily cleaned off the walls and floors that it stuck to. No mood difference was noted in participants. The data size was not large enough to be significant.
On the other hand, even if I assume this is all true, I would first worry about the ozone exposure. Fortunately, it is possible to filter out ozone using carbon-rich paper filters, and the ozone does kill all bacteria (and some viruses) while it is present.
So if this theory was true, the best air sources would be first ionized, then filtered (removing the dust, bacteria, viruses, and ozone), and then accelerated into the room. This also gives me a plan to experiment with this idea.
Get 3 groups of 30 people each. One group is put into a room in which the air is positively charged, filtered, then blown into the room. One group is put into a room in which the air is negatively charged, filtered, and then blown into the room. The last group is the control, and their air is not charged, but merely filtered. The filtering takes place some distance from the room so that it's not apparent which group you're in. The rooms are otherwise identical, and can support sleep, work, games, and eating. We have the group live there a period of time to be decided later. At the end of the period, we evaluate the groups for changes in health and mood, and we also measure bacteria concentrations in the rooms, walls, and floors.
If the theory is true, then I would expect that the positively charged room would be in better health than the control, which would be in better health than the negatively charged room, but that bacteria levels would be highest in the control room.