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Which type of air cleaner is good for libraries?

How to choose an air cleaner


1-Ozone Generators

 Ozone generators that are sold as air cleaners intentionally produce the gas ozone.

Ozone is a molecule composed of three atoms of oxygen. Two atoms of oxygen form the basic oxygen molecule, the oxygen we breathe that is essential to life. The third oxygen atom can detach from the ozone molecule, and re-attach to molecules of other substances, thereby altering their chemical composition. It is this ability of ozone to react with other substances that forms the basis ozone generators principle. Ozone at safe levels does not clean the air. Independent studies by the U.S. Environmental Protection Agency, the Consumers Union, and others have shown that these devices do not effectively destroy microbes, remove odor sources, or reduce indoor pollutants enough to provide any health benefits. Ozone masks the odor of other indoor pollutants by deadening the sense of smell. It also reacts with certain indoor pollutants to produce toxic byproducts, such as formaldehyde. Ozone is used effectively in water to destroy microbes, but ozone in air must reach extremely hazardous levels (50-100 times the outdoor air quality standards) to effectively kill microbes.

The Federal Trade Commission (FTC) has successfully sued a major manufacturer of ozone generators for making unsupported health claims. These claims involve the products purported ability to remove indoor air pollutants, to prevent or relieve allergies, asthma and other health conditions, or to create harmful by-products such as formaldehyde ( http://www.arb.ca.gov ).

The same chemical properties that allow high concentrations of ozone to react with organic material outside the body give it the ability to react with similar organic material that makes up the body, and potentially cause harmful health consequences. When inhaled, ozone can damage the lungs (see - "Ozone and Your Health" - www.epa.gov). Relatively low amounts can cause chest pain, coughing, shortness of breath, and, throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections. People vary widely in their susceptibility to ozone. Healthy people, as well as those with respiratory difficulty, can experience breathing problems when exposed to ozone. Exercise during exposure to ozone causes a greater amount of ozone to be inhaled, and increases the risk of harmful respiratory effects. Recovery from the harmful effects can occur following short-term exposure to low levels of ozone, but health effects may become more damaging and recovery less certain at higher levels or from longer exposures (US EPA, 1996a, 1996b).

 The Food and Drug Administration (FDA) requires ozone output of indoor medical devices to be no more than 0.05 ppm. The Occupational Safety and Health administration (OSHA) required that workers not to be exposed to an average concentration of more than 0.10 ppm for 8 hours. The national Institute of Occupational Safety and Health (NIOSH) recommends an upper limit of 0.10 ppm, not to be exceeded at any time. At low concentration safe limit, ozone has no effect or not efficient to remove odors or gaseous materials. (www.epa.gov)

The American Lung association ( www.lungusa.org ) and California Department of Health Services ( www.arb.ca.gov )suggest that ozone generators not be used.

The Canadian Standards Association (CSA) no longer approves ozone generators for use in homes. Most of the ozone generators that are in homes were sold door-to-door across Canada . They were not sold in stores.

Because of highly reactivity, Ozone can react with all organic material in library and museum to destroy them. Suggested ozone concentration limits for the above cited environments are no higher than 0.001 to 0.013 ppm, with the most frequent recommendation being 0.001 ppm ( De Nuntiis et all , iaq 2004 ).

Ozone generators do not remove solid particles (e.g., dust and pollen).

Totally, ozone generators air cleaner are not recommended to be used in libraries or home.

2- Ion generators

Ion Generators or electronic air cleaner act by charging the particles in a room. The charged particles are then attracted to walls, floors, draperies, etc. or a charged collector. Ion generators, especially those that do not contain a collector, may cause soiling of walls and other surfaces. In the case of libraries, the charged particles go directly settled down and attached on books. This as we explain here create a new health problem may be worth than the initial problem.

Ion generators with collectors called: electrostatic precipitators (ESP) are equipped with electrostatic precipitators, employ an electrical field to trap particles. Using collectors on electronic air cleaner could reduce the problem of settling down of particles on books. Bur still, should be checked up how much charged particles can escape from electrostatic precipitators (collectors).

Ion generators and electronic air cleaners produce ozone, particularly if they are not properly installed and maintained. Ion generators have no effects on gaseous materials.

Totally before further research can clarify the problem of ozone by-product and charged particles which can escape from electrostatics precipitators; we can not be sure of safety and final efficiency of this type of air cleaners for using in libraries and museums.

3-Mechanical air cleaner

 3-1 Static air cleaners

Use special fibrous material that can be mounted into the ductwork of air conditioner and furnaces systems. This kind of filters can eliminate large and in the best cases medium size particulate materials. To eliminate fine particulate materials very fine structure of fibrous materials should be used. This result in high pressure lost in air conditioning conduits that are not generally acceptable for air conditioning system designers. That `s why using an air cleaner with HEPA filter inside rooms is needed to eliminate the fine particulate matter.

The best results achieved when fibers are given permanent electrical charges to attract any particles in their vicinity, with ability to capture small- or medium-sized particles.

3m has developed high efficiency filters of this type which clean 50 times better than foam standard. For more information please click here.

Central forced air systems in buildings usually have a rectangular, one-inch thick fiberglass filter that slides underneath the furnace fan. You can easily replace this filters with a high quality electrostatics charged filters. Prefabricated high quality filters are available from 3 m

3-2 Movable HEPA air cleaners

High-Efficiency Particulate Air Filters (HEPA) are a further extension of extended-surface media filters. A HEPA filter has been traditionally defined as an extended-surface dry-type filter having a minimum particle removal efficiency of 99.97% for all particles of 0.3 micron diameter with higher efficiency for both larger and smaller particles.

There are two kinds of portable air cleaners on the market: small tabletop units and larger console units that can be moved from room to room. tabletop units have been shown that provide little benefit, except in the area next to the machine

The simplest portable cleaners have a filter that will need replacement at regular intervals. Better quality air cleaners incorporate a HEPA or HEP-type filter. The HEPA filter is expensive, sometimes costing half as much as the entire appliance. (True HEPA filters must meet precise standards relating to the percentage of specific particles captured in a laboratory test. Some filters, described as HEPA-type filters are now being sold. These contain a filter made with HEPA materials, but do not quite meet the efficiency standards of true HEPA filters.)

While the cost of replacement of HEPA filter is a disadvantage, the great advantage of this kind of filters is that it produces no side products like ozone and electro-statically charged particles.

HEPA filter does not remove gaseous materials.

4-Gas removal air cleaners

Gaseous pollutants are trapped or destroyed as the air is drawn through materials such as activated charcoal or alumina coated with potassium permanganate

5-Hybrid Air cleaners,

Which contain two or more of the particle removal devices discussed above. Every device can solve a part of problem or cover the disadvantage of other devices.

Our recommendations:

 1-In libraries and museum we need before everything installing static filters in air conditioning and furnaces conduit. The filters which use permanently electrostatics charged fibers give better results.

3m has developed high efficiency filters of this type which clean 50 times better than foam standard. For more information please click here .

2-Scince there is no static filter that can remove all particles and because of existence of air pollution sources inside libraries (the books it selves for example) you will need to use portable air cleaner.

Between all air cleaners we recommend strongly use HEPA filter which can remove all dust particles including ultra fine particles, allergens, dust mite, molds, spores etc, and has no side- products like ozone and electro-statically charged particles. You may prefer to use a hybrid air cleaner with gas removing filter which can remove also fumes and chemicals. These chemicals may be produced from materials used in books (adhesive, plastic etc) chemical used for books conservation, pesticides used against molds and the usual hazardous chemicals comes from outside.

Below you find one of these hybrid air cleaners that we select from Austin air Cleaner and we believe is very good for libraries, museum and homes. For more information pleas click here.

 
Click here to enlarge
 
 
The filter is consisted of:

1-A large outer filter traps the large airborne particles, lint and pet hair.

2-The pre-filter eliminate larger dust particles.

3-A full 15 lb Carbon Active Zeolite to eliminate over 3000 toxic gases and odors.

4-A True Medical HEPA filter, the same as used in hospitals clean rooms. HEPA filter removes 99.97 particulate mater larger than 0.3 microns
 
The 3 initial filter layers by separating large particles and toxic gases protect HEPA filter. This is the main point why the HEPA filter needs to be changed once per every 5 years. This can save about $2000 the fees for HEPA filter replacement in 5 years in comparison with other air cleaners. The pre-filter , very cheap in price, needs to be changed once per year.
 
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