Ionic Air Purifier Technologies - Boon or Bane? » Allergies - Learning From Common Types Of Allergies

« « Man's Best Friend - Dog Allergies | Consider Fluconazole For Mold Allergies » »

Ionic Air Purifier Technologies - Boon or Bane?

Sunday, January 11th, 2009 Subscribe To Our Feed

Introduction

Ionic air purifiers hold the promise of clean air, purified of all known harmful contaminants that threaten our health. These harmful contaminants are not visible to our naked eyes. Invisible ions battling invisible contaminants appears to make perfect sense. Intuitively, the logic is appealing. But these days, finding a simple and quick solution is rare. Googling the subject unearths a ton of controversy. Obviously, I must resist the urge to go by intuition and grab the first ionic air purifier that I lay hands on. Effectiveness is important but safety is paramount in the criteria for selecting an ionic air purifier.

The recent China melamine saga that killed infants also is a timely reminder to us that in buying into any technology or any product, all claims by manufacturers and distributors must be screened to the fullest extent that our resources permit. This is especially so where the key reactive agent is invisible to the naked eye. Investigating ionic air purifier technologies falls within this ambit as the reactive agents are invisible ions.

In this article, I am laying out the roadmap as I look into the existing ionic air purifier technologies in the global marketplace. As laypersons, I believe we have to adopt a back-to-basics approach to try and understand the technologies. The creation of a powerful invisible defence shield against airborne molecular contaminants is increasingly taking centrestage. The dominant global health threat under the scrutiny of scientists is the avian flu virus.

Types of Ionic Air Purifier Technologies

Broadly speaking, air purification technologies can be deployed in either passive or active modes. In passive mode, impure air is drawn into the air purifier for reactive agents to work on before re-emerging as cleaned air into the environment. Active generally means dispersive processes by which the impure air is penetrated and purified by the reactive agents. Combinations of both passive and active modes are often found in many types of ionic air purifiers.

In the global market today, ionic air purifier technologies include the following categories:

(A) Ion generator - positive and negative ions
(B) Ion generator - negative ions only
(C) Photocatalytic Oxidation (POC)
(D) Electrostatic filter
(E) Combos

Ion Generator - Positive and Negative Ions

This combination of positive and negative ions appears to show the most promise for the future of ionic air purifier technology. They have been named as plasmacluster ions by Sharp Corporation, the Japanese corporate powerhouse that invented them.

Sharp explains that the plasmacluster of positive and negative ions clump to harmful airborne bacteria and viruses. In so doing, the production of hydroxyl is activated. Hydroxyl, also known as nature’s detergent, is a powerful reactive species that plucks out hydrogen molecules from the organic structure of these airborne particulates thereby destroying them. This chemical reaction generates harmless by-products, the main of which is water.

This technology uses a differential ion generator, comprising a positive and a negative ion generator which can be powered in alternate cycles to control the type of ions generated.

Advocates of the positive and negative ions combination claim that a balance of both these ion types is to be found in places like waterfalls and pristine forests, i.e. this is the actual state in nature. In contrast, proponents of negative ions technology insist that negative ions fill natural habitats and that the presence of positive ions is harmful. In this regard, I have yet to find independent scientific studies as evidence for the contradictory claims of both camps.

Ion Generator - Negative Ions

The traditional ionic air purifier produces only negative ions. This method seems to dominate market share in the industry but is coming under serious threat from Sharp’s plasmacluster positive and negative ions technology.

It is claimed that nearly all harmful airborne particulates like dust, smoke and bacteria etc have a positive charge. Negative ions from the air purifier attach themselves to these particulates until they get weighed down and fall to the ground. Regular vacuuming removes these impurities from our environment. Weighing down the particulates does nothing to destory them, according to critics, and merely walking on them causes the air to be polluted again.

Apparently, there are a number of ways to produce negative ions. This has significance as the various methods result in different by-products, some of which are harmful. These methods include:

(1) Water method - this employs what is known as the waterfall or Lenard Effect. Onto an electrically-charged metal plate, water droplets are splashed. The charge splits the water droplets resulting in the production of a large number of negative ions. Proponents of the water method believe it to be free of harmful by-products.

(2) Electron radiation method - this is based on a single negative discharge electrode needle. Millions of negatively-charged electrons are produced when a high voltage pulse is applied to the electrode. It is claimed that this method produces no ozone. This is believed to be due to the application of a “smaller” energy pulse.

(3) Corona discharge method - this is based on a dual electrode model, a sharp metal electrode and a flat electrode. Between the two electrodes, a high voltage is applied. This creates a massive movement of electrons between the electrodes and ionises the air in between them. An inherent flaw of this method is the production of harmful by-products like ozone and nitride oxide.

Photocatalytic Oxidation (POC)

This technology is commonly applied in a passive mode. It is also based on the powerful reactive agent hydroxyl which purifies impure air that is pulled through the air purifier.

Germicidal ultraviolet (UV) light is commonly shone on a catalyst (usually titanium oxide) to produce hydroxyl, oxygen and peroxide, all of which are potent oxidising agents that are very effective at destroying the organic structure of micro-organisms and gaseous volatile organic compounds.

The key pillar of POC technology is its comprehensive coverage. Proponents of this technology claim that POC inactivates ALL categories of indoor pollution, including:

(1) airborne particulates i.e. dust, pet dander, plant pollen, sea salts, tobacco smoke, industrial and car pollution, etc

(2) bioaerosols i.e. biological compounds that may be infectious (e.g. viruses and pathogenic bacteria) or non-infectious (e.g. non-pathogenic bacteria, molds, cell debris)

(3) volatile organic compounds (VOCs) i.e. gaseous odours and chemicals - toluene, chloroform, hexane, ethanol, formaldehyde, ethylene etc, all common emissions from everyday products of our modern home.

Detractors of POC technology are wary of the inability of hydroxyl to distinguish between the organic structures of molecular contaminants and that of our nose membrane, lung tissue and eye cornea.

Electrostatic Filter

This technology appears to have originated in heavy industries which produced abundant pollutants. In the most common electrostatic filter arrangement, there is a porous dielectric material positioned between two electrodes. A dielectric material does not conduct electricity while metallic electrodes are good conductors that transmit or receive electricity.

As impure air is drawn into the electrostatic purifier, it passes through the dielectric material which acts as a sieve. Electrostatic electricity between the electrodes causes airborne particulates i.e.dust, smoke contaminants, etc, to adhere to the surface of the dielectric. Purified air is pushed out of the purifier and re-circulated.

Very often, an ion source is inserted before the electrostatic filter to charge the airborne particulates. These impurities, so charged, stick more effectively to the dielectric material.

The general criticism of ionisation technology applies to electrostatic filters as well i.e. that harmful ozone is a by-product.

Combo Ionic Air Purifiers

To cater to the various adherents and critics of the diverse technologies, combos incorporate all or some of the above types of technologies. Combos may include:

(1) adsorptive materials such as activated carbon or oxygenated charcoal (known for its extremely porous large surface area) are added to POC technology to enhance the removal of VOCs;

(2) oxidizing catalysts like titanium oxide are coated on various components of all types of air purifiers to enhance VOC elimination;

(3) reducing catalysts such as manganese dioxide are coated near the exit outlets of many air purifiers to reduce reactive species like ozone and nitric oxide which may be harmful;

(4) generating ions by differing methods such as using microwave, UV light, radio frequency waves, and direct current;

(5) tweaking the specifications of any ionic air purifier technology so as to attain the well-known HEPA status without actually using HEPA filters.

Obviously, the process of selecting the most efficient and effective ionic air purifier involves analysing a deluge of information. And I have not even touched on the safety aspects of each technology. Nor have I studied in detail the claims of each technology. It is natural to want to quickly want something that promises to improve the air quality in your homes, offices, factories, schools etc. But I urge you to do your homework and don’t forget to visit me for updates as I continue my search for the ideal ionic air purifier.

To easily receive updates on new articles, subscribe to The Ionic Air Purifier Blog today.

Share and Enjoy: