Personal Opinion on Air Purifiers
Making a choice on the best air purifiers available
There is a lot of controversy surrounding the cheaper units on the market which ionize the air in an effort to make air particles heavier so that they drop to the floor. For more information on how these units work read the following article; Your Ionic Air Purifier Alternatives
Personally I would feel a little dubious about having a device that as a by-product of the method it uses to operate, it will also produce ozone. Regardless of the volume of ozone it is purported to produce, small or large, what really is the point of using a machine that makes the dirt particles in the air (which you are trying to remove) heavier, so that they fall onto surfaces, where you either have to dust them off (so resulting in some dirt becoming airborne again), or having to vacuum the dirt anyway from the carpet or floor?
These ionizer units (distinct from the very expensive ones that Consumer Reports rates highly) are just not as effective as a HEPA certified filter. Period. They have other upsides like making the air smell rain fresh and silent operation, but they simply do not have the efficiency that a HEPA filter provides (filtering 99.97% of .3 micrometre particles).
At least with a HEPA filter, you know that you are trapping the particles and actually removing them from the environment immediately, rather than sending them out of the back end of the machine where they are still airborne, but just waiting to settle to the ground. In the meantime, with them being airborne still, they can just as easily "settle" in your lungs or nasal passages!
I ask you - Do you really want that?
For my money I would always go for a HEPA filter unit, or a combination HEPA and UV purifier. But is there something even better available?
There are some very good air purifiers on the market. The main companies are:-
- Sharper Image
- Hamilton Beach
- Bell & Howell
- Surround Air
Before you can find the one that is right for you you must understand the technical differences among these purifiers.
HEPA Filter air purifiers
HEPA (High Efficiency Particulate Air) filters utilize a cloth type filter that can trap 99.9% of particles 0.3 microns or larger in size, and use a fan to force air through the machine. HEPA filters can be very effective at clearing out almost any harmful particles from the air in a room. These devices usually have a replaceable filter that can last several years depending on how filthy the air is in your home. Some people don't like the noise level given out by a HEPA machine (because it requires a suitably powerful fan to force the air through the filter), but it can usually remove far more airborne pollutants and particles than an ionic air purifier.
Advantages: Allergens are immediately captured; not being released into the air once trapped.
Disadvantages: HEPA will not eliminate chemical fumes, gases, cigarette smoke, or odours.
Ozone air purifiers
Ozone is a highly reactive oxidant which can destroy certain bacteria and chemicals. Although ozone is very effective against strong odours, there is a caution you should consider which was alluded to further above.
When ozone reacts with substances being carried in the air, those substances are broken down by the reaction into other materials that are also pollutants. And this is where the controversy lies with ozone machines. Some ozone purifiers are adjustable and can be run on a low setting, which is often the advice given by manufacturers. But, if you need to clear a room of smoke or odours, then you can run it on a high setting while keeping people out of the room altogether. Later, you simply turn the machine off and open some windows to clear out the ozone.
Advantages: Can be extremely effective against odours.
Disadvantages: In-effective on most chemicals and allergens.
Ionic air purifiers
Ionic air purifiers do not have a cloth filter like the HEPA machines. Instead they work by "ionizing" the air, causing the airborne particulates to gain a positive or negative charge. So what dies this do?
The applied charge is necessary for two reasons. The air ionizer contains collection plates that have an opposite charge from the particles in the air, so those particles are drawn to the collection plates (this type of purifier is referred to as "capture" ionic purifiers).
Also, the particulates can become attracted to other particles that have an opposite charge. When this happens the two particles with opposite charges end up sticking together, increase in mass (become heavier) and fall out of the air as dust (these machines simply release ions into the air without capturing them on plates). One of the main reasons many people like ionizers, is because they are very quiet compared to most fan-forced HEPA machines.
Advantages: ionization can remove extremely fine particles anywhere in a room; even up to several feet away from the machine.
Disadvantages: ionizers are not effective on odours; while not killing germs, they will remove them from air confined in a house.
Carbon air purifiers
Activated carbon air filters consist of a system of pores in the carbon which are tiny in size. The pores are highly absorbent, reacting chemically with particles that pass through them, and the particles and odours actually bond with the carbon.
This is the most absorbent filter on the market today, so it is extremely effective in capturing certain types of particles. Note also that most carbon activated devices also incorporate HEPA technology, thereby combining the advantages of both types of technology.
Advantages: Carbon filters are highly effective with chemicals, gases, smoke, and odours.
Disadvantages: Carbon is not effective with allergens and micro-organisms.
Ultraviolet light air purifiers
Ultraviolet (UV) lamps are well known for their ability to sterilize micro-organisms that pass through the light. This includes germs, viruses, bacteria, and mold; so micro-organisms, after treated with this light, can no longer reproduce and grow. At least, we know this to be true when UV light is used in sufficient dosage and a sufficiently long period of time to do its job.
Sunlight is the most natural source of UV light, and bacteria cannot thrive when exposed to sunlight. This was a fact known by ancient physicians, and doctors before modern anti-bacterial medicines and anti-biotics were available, where soldiers who sustained injury on the battle-field would be told to clean the wound and let sunlight fall on the exposed flesh so as to kill the bacteria and allow fresh air and natural healing to take place.
When used in an air purifier the question is: Does the UV light have enough time to perform and sterilize correctly, while air is moving through it, possibly at a brisk rate of speed? There is an innovative approach that uses UV lamp combined with a HEPA filter, so particles trapped in the filter are slowed and can be treated with UV light for an effective amount of time.
Advantages: UV helps destroy the micro-organisms that cause disease.
Disadvantages: Not effective on allergens, smoke, odours, or chemicals.
Purifying hydroxyl radicals
Hydroxyl radicals are powerful cleansing agents that occur naturally in the earth's atmosphere. They are created when oxygen atoms pull a hydrogen atom from water vapour, which then form the radical.
Hydroxyl radicals are one million times faster at destroying pollutants in the air than ozone. They are the most powerful method of neutralizing mold, bacteria, and viruses.
New proprietary technology has combined hydroxyl radical technology with ultra violet light and negative ions resulting in an air purifying system that neutralizes every category of pollutant in your home, including odours, without the need for filters!
Advantages: removes every category of pollutants when combined with negative ions and UV light technologies; no filters needed; inexpensive.
Disadvantages: only available from one manufacturer. No HEPA filter. Relies on controlled ozone levels and ionization.