What is the best type of Air purifier to buy?

My 2 1/2 year old has asthma. So i need to buy a purifier for the room. Which one is the best kind? And I heard the Ozone kind are suppose to be bad for you, so I want to make sure I don't buy one of those. Please tell me your experience.

Question asked at Yahoo Answers

Despite manufacturer's claims, ozone air purifiers don't remove particles from the air that may trigger asthma attacks. In fact, inhaled ozone may even make asthma worse.

Ozone generators sold as air purifiers intentionally produce ozone, which is a toxic gas. Ozone is a molecule made of three atoms of oxygen. Two of these atoms form the basic oxygen molecule. The third atom can detach from the ozone molecule and reattach to molecules of other substances, changing their chemical composition. This is the basis of manufacturer claims that ozone "purifies" the air. But inhaling ozone — even in small amounts — can damage lung tissue. Inhaled ozone may cause throat irritation, coughing, chest pain and shortness of breath. It can increase the risk of developing a respiratory infection.

Some ozone air purifiers are made with an ion generator or "ionizer" in the same unit. You can also buy ionizers as separate units. Ionizers do take particles out of the air. Ions stick to particles, causing them to attach to nearby surfaces or to each other and settle out of the air. But ionizers don't work any better than high-efficiency particulate air (HEPA) filters or electrostatic filters in removing allergens from the air and may generate unwanted ozone.

ypes of Air Purifiers

There are basically two types of Air Purifiers:

* Arrestors, which physically trap pollutants.

* Non-Arrestors, which alter the pollutants characteristics without capturing them.

Arrestors

Mechanical Air Filters


Most mechanical air filters use a woven material to capture particles as the try to pass thru. Because they accumulate trapped particles, Mechanical air filters will require maintenance. Some are washable, otherwise dirty filters are discarded and replaced by new ones. As dirt accumulates in the filter, the filter's effectiveness will be reduced by restricted air flow; so maintenance is very important. Air filters with the ability to trap 99.97% of particles larger than .3 microns in size are called HEPA or High Efficiency Particle Arrestor.

Absorbents such as charcoal can also be used to Arrest pollutants. Porous materials like charcoal act like sponges to absorb odors and gaseous pollutants. Because the pollutants accumulate within the charcoal, these too must be regularly maintained.

Electrostatic or Electronic Air Purifier

An Electrostatic or Electronic Air Purifier places a charge on particles as they pass by an electrical grid. This gives them a charge which makes them "sticky". The "sticky" particles then pass by some oppositely charged collector plates. Since they are "sticky" with the opposite charge, the particles cling to the plates. Because the plates accumulate particles, they will eventually become covered and need washing, so an electrostatic air purifier's ability declines with use and requires maintenance. The electrical charge may also produce ozone.

Non-Arrestors

Ionic Air Purifiers

Ionic Air Purifiers generate an electrical charge. The pollutants in the air become "sticky" and cling to the walls and ceiling and furniture in the room. Because the pollutants are "sticky" they may also cling to the inside of your lungs when you inhale them. Ionic Air Purifiers may also produce Ozone as a byproduct. Ozone may be considered an irritant.

Ozone Air Purifiers

Ozone Air Purifiers manufacturer a form of oxygen that combines with pollutants and changes their chemical make up. Ozone Air Purifiers are mostly used for smoke and odor removal . Again, ozone is considered an irritant and may be harmful in large doses.

Ultra-violet Air Purifiers

Ultra-violet Air Purifiers are used to kill bacteria, molds, and viruses. Ultra violet light is harmful to the eyes, so the air must be drawn into the air purifier where the pollutants are exposed to the deadly light. The speed of the air and the light intensity are critical to it's success. This type of air purifier does not remove particles, but can be combined with a mechanical filtering device to do so. Ozone may be a byproduct of this type of Air Purifier.