While most manufacturers of ozone air purifier systems  use the older, corona discharge (high voltage electricity) method to create ozone, Refulgent Catalysis Ionizing RCion's Photohydroionization TM AHPCO or RCIon Cell is the latest advanced oxidation technology used in air purifiers that consists of a proprietary, high-intensity broad spectrum UV tube (100 – 300nm) in a hydrated catalytic matrix cell. Low-level ozone is produced in the cell, the majority of which is converted into airborne hydro peroxides and super oxide ions. The UV bulb is encased in a protective poly tube to prevent any glass or mercury breakage/leakage. Also, the entire assembly is encased in a protective metal cell. Like ozone, UVGI destroys bacteria, viruses, and fungi and has been used in medical facilities for years for those exact purposes. Combining photolic ozone with UVGI and moisture (humidity) produces a powerful oxidant known as hydroxyl radicals.

These purifying hydroxyls have been described as "the single most important cleansing agent in the earth's atmosphere". They break down hazardous organic compounds and are a catalyst in the chain reaction necessary for contaminant oxidation. In addition to these purification methods, Refulgent Catalysis Ionizing RCion air purifier units produce negative ions via ultraviolet wavelengths. The APHCO or RCion Cell Technology combines the best of science and electronics to produce the purest of air.

A comparison of indoor air quality systems for HVAC contractors utilizing filterless system of Ozone and UV light:

• UV Germicidal Lamps
• UV Ozone Lamps
• Corona Discharge Ozone Systems
• UV Catalytic Oxidation Systems
• Photohydroionization™ System
• APHCO or RCIon Cell

General

Ultraviolet Light and Ozone receive a lot of attention concerning indoor air quality. Both are nothing new. They have been used for decades in hospitals, medical applications and the food industry. This technical overview will outline each of the technologies and discuss the pros and cons of each.

UV-C – Germicidal Lamps

These are rapidly becoming very popular as an easy fix for the air conditioner coil mold problem. This is the most prevalent cause of the building mildew smell you get when you enter an air-conditioned sick building. UV-C (254nm) lamps are basically similar to sun lamps and are typically only effective on microbials that pass by within a few inches of the lamp or areas where the light is shining directly on for extended periods of time, such as the air conditioner coil (see article in HVAC News – yellow highlighted).

Pros:
Low cost, easy installation, and effective on suppressing mold growth on the coil.

Cons:
Not effective at killing airborne mold unless numerous lamps are used (see article) only effective on the surface of the coil that is in direct light. This leaves much of the coil with no treatment. Does not provide ongoing room protection. Most UV systems install a glass UV mercury bulb without protection from breakage. A broken bulb could release mercury, a potential environmental and health hazard. Minimum of two lamps must be used to cover at least one-quarter of the coil surface (the upper half of the outer coil). For one-half coverage, three to six lamps must be used. 100% coverage is not practical.

UV-C – Ozone Lamps

UV lamps in the 185nm range produce low-level ozone, just as the sun does, which is very effective in odor microbial reduction and VOC’s.

Pros:
Low cost, easy installation, and effective on mold, smoke, odors and bacterial. The ozone gas travels through the house to provide ongoing treatment, unlike the UV-Germicidal Lamps where only the air that passes within inches of the bulb is treated.

Cons:
Ozone is a concern to some people. Improper systems could produce ozone levels exceeding Federal guidelines. Ozone does not work on all odors and VOC’s. Most UV systems install a glass UV mercury bulb without protection from breakage. A broken bulb could release mercury, a potential environmental and health hazard.

Corona Discharge Ozone Systems

These systems simulate lightning with a corona electric arc or spark. Strong ozone is produced by converting the oxygen (O₂) to ozone (O₃).

Pros:
Low cost. Ozone effective on odors, bacteria, VOC’s and mold.

Cons:
Air is 80% Nitrogen and 20% Oxygen. These units convert Oxygen to Ozone. They also convert the Nitrogen to Nitric Acid and Nitric Oxide, which causes maintenance problems due to corrossion. They produce high concentrations and levels of ozone, usually over Federal safe limits and airborne Nitric Oxide. These systems typically will require expensive monitors to control ozone levels. Also, aRCIonng (sparking) can be a noise and safety problem.

Note:
Corona Discharge Ozone Units should never be used for air purification in occupied areas, as they will usually exceed Federal safety limits of ozone.

UV Catalytic Oxidation Systems

This system utilizes a Titanium grid as a catalyst for UV-C (254nm) germicidal light. Air that passes through the grid and comes in contact with the catalyst is purified by Hydroxyl Radicals that are formed on the Titanium grid. Also, the UV-C light rays kill microbials that pass by them.

Pros:
Effective on the air that passes through the system for mold, bacteria and VOC’s.

Cons:
Expensive, large, substantial installation, and not effective on odors. Only treats the air that contacts activated target surfaces as it passes through the unit. Most UV systems install a glass UV mercury bulb without protection from breakage. A broken bulb could release mercury, a potential environmental and health hazard.

Photohydroionization™ System

This is an advanced oxidation system that consists of a UV-Ozone producing bulb (185nm) targeted on a catalyst target, which produces low-level ozone. Hydro peroxides and super oxide ions

Pros:
Low cost, low maintenance (yearly), and easy installation. Not only does this process treat the air that passes through the device, it sends low-level ozone (.04 ppm), hydro peroxides and super oxide ions into the room for complete coverage.

Note:
The Federal limit for ozone devices is .04 ppm.)

Cons:
Ozone is a concern to some people even when it is within federal safety limits. Most UV systems install a glass UV mercury bulb without protection from breakage. A broken bulb could release mercury, a potential environmental and health hazard.

APHCO or RCion Cell™ (Photohydroionization™ Cell)

This is the latest advanced oxidation technology that consists of a proprietary, high-intensity broad spectrum UV tube (100 – 300nm) in a hydrated catalytic matrix cell. Low-level ozone is produced in the cell, the majority of which is converted into airborne hydro peroxides and super oxide ions. The UV bulb is encased in a protective poly tube to prevent any glass or mercury breakage/leakage. Also, the entire assembly is encased in a protective metal cell.

Pros:
Low cost, no maintenance (once every 3 years), easy installation, airborne hydro peroxides, super oxide ions and very low-level ozone (.01 - .02 ppm*) travels through the house providing 24-hour protection against airborne mold, bacteria, viruses, odors and VOC’s. The cell also acts as a germicidal lamp and treats the air that passes by it.

*Note 1:
Federal safety limits are .04 ppm. At .01 - .02 ppm this is not considered an ozone device.

*Note 2:
The Chinese Government has tested and passed the APHCO or RCion Cell for use in preventing SARS in Chinese subways.

Cons:
None

In Summary

The APHCO or RCion Cell Technology is a vast improvement over ozone units using the corona discharge method of creating ozone which requires 5,000 - 10,000 volts of electricity.