I know a number of you with allergies to airborne particles such as dust, pollen, etc (or even who don't) use air purifiers. These equipment definitely don't come cheap, but worse, some of them may even aggravate your conditions, such as in the case of those with allergic asthma.

A new study revealed another warning to those using certain indoor air purifiers: In the presence of limonene-containing cleaning products, these purifiers may actually make the air dirtier.

Continuous operation of the ionic purifier without limonene resulted in a slight reduction in the average particle concentration, while operation of the ozonolysis purifier resulted in no detectable effect on the particle level. When limonene was added to the room, the particle concentration shot up in both cases, on some occasions up to 100 times the original level. Adding limonene to the room when a purifier was not operating produced little change in the overall particle level.

Apparently, it depends on the type of air purifier: commercial ionic purifier that emits about 2 milligrams of ozone per hour, or an ozonolysis purifier that emits approximately 100 milligrams of ozone per hour. I also browsed through the ionic purifiers in Amazon.com, and saw a model that has an "OzoneGuard": Ionic Breeze Quadra Silent Air Purifier.

Exclusive OzoneGuard in the front grill converts by-product ozone to harmless oxygen as clean air circulates back into the room. Ozone accumulation is far below safety requirements for air cleaners.

Might be a good option.