ozone should never be used in occupied spaces

[Guest guest]

From: " Jim H. White " <systemsa@...>

Date: Sat Jun 25, 2005 1:20 pm

Subject: Re: [iequality] IAQ in central ac systems systemsa@...

iequality/message/3299

Ozone generators and/or ozone should never be used in occupied

spaces as it

does lung damage even at low concentrations. Any employee

satisfaction can

be due to damage smell sensors in the nasal passages, not in a real

improvement. See Health Canada

(http://www.hc-sc.gc.ca/hecs-sesc/cps/publications/ozone.htm

http://www.hc-sc.gc.ca/hecs-sesc/cps/publications/ozone_qa.htm) and

the US

EPA (http://www.epa.gov/iaq/pubs/ozonegen.html

http://www.epa.gov/iaq/pubs/airclean.html) sites for reasons why you

should

not use ozone indoors.

Jim H. White SSAL

Subject: Aerotech Laboratories, IAQ Tech Tip #62: Ozone Generators

and IAQ

Date: Tue, 9 Oct 2001 13:47:29 -0700

Ozone Generators and IAQ

With the considerable recent media attention focused on the issues

of indoor air quality, microbial contaminants in particular, ozone

is once again being touted as a remedy for all manner of indoor air

quality concerns. Marketing literature from distributors of ozone

generators boast claims of eliminating microbial contaminants

through the use of ozone. One website claims " Ozone helps kill mold

and mold odors with large ozone dose shock treatments " and " Ozone

may be the only way to save your home from deadly mold " . The

propaganda goes as far as claiming that ozone destroys mold leaving

only oxygen, hydrogen and carbon dioxide. These are the kind of

unsubstantiated claims that led to a $1.49 million civil penalty

against Alpine Industries in April of 2001 and a Court Order to

cease making health claims for its ozone generators. A recent study

has demonstrated that gas phase ozone is ineffective in reducing the

viability of Penicillium spores on building materials at levels as

high as 9 parts per million (ppm), levels that are much higher than

those attainable under field conditions (Appl.Occup.Environ.Hyg. 12

(8), August 1997). Recent studies have also implicated a synergistic

effect between fungal spores and ozone and increased symptoms of

asthma in asthma patients using an inhaler on an as-needed basis

(Am.J.Respir.Crit.Care.Med. 154(3 Pt 1):633-41, Sept. 1996).

The U.S. Occupational Safety and Health Administration (OSHA) limits

ozone exposure in industrial settings to 0.1 ppm over an eight hour

day, six days per week. The Food and Drug Administration has set a

limit of 0.05 ppm for the ozone generated from electronic air

cleaners used as medical devices. The Environmental Protection

Agency has stated:

Available evidence shows that, at concentrations that do not exceed

public health standards, ozone is generally ineffective in

controlling indoor air pollution. The concentration of ozone would

have to greatly exceed health standards to be effective in removing

most indoor air contaminants

From: " Carl E. Grimes " <grimes@...>

Date: Mon Oct 11, 2004 1:29 pm

Subject: Re: []^ Ozone educational web sites

This is my last comment on this ozone discussion: Ozone is not

enriched oxygen. Ozone is a pollutant. The two have different

properties.

Carl Grimes

Healthy Habitats LLC

From: Jeff May <Jeff@...>

Date: Thu Oct 7, 2004 10:31 pm

Subject: Re: Ozone for killing mold

1. Common indoor molds (Penicillium, Aspergillus, Cladosporium, etc.)

are NOT wood-destroying organisms (many cannot even digest

cellulose),

so they do not consume wood in our houses. Even Stachybotrys, which

can

be cellulolytic, does not destroy wood; these molds are called

microfungi. Brown rots and white rots (mushroom-forming fungi or

macrofungi) destroy wood, digesting either cellulose, lignin or

both..

Though there are outdoor (and indoor) spores in the air, mold is not

all

around us and in every room (unless in a very problem environment).

4. As Jim Holland noted in a previous e-mail, FDA-approved ozone

generators do NOT inhibit the growth of fungi or even kill spores. On

the other hand, many ozone generators create concentrations of ozone

above the FDA limit of .05 ppm. (Anyone with an ionizer or ozone

generator concerned about ozone concentrations can purchase a two-

test

kit from IQAir for about $8.)

5. Filtration is the most effective means to remove aerosolized

particulates.

6. Air purifiers may remove spores from the air, but they do NOT

control

mold. As you noted, the only way to control mold growth is to control

relative humidity and water. It is foolish to spend money on any

type of

air purifier without eliminating the obvious sources of spores first.

Jeff May

Author, " The Mold Survival Guide "

s Hopkins University Press

From: RLLIPSEY87@...

Date: Wed May 28, 2003 8:53 am

Subject: Re: [] Digest Number 1636

Ozone is a toxic chemical whether it is produced naturally in a

thunderstorm or

produced by ozonators or " air purifiers " (or sold by any other

name) .

Ozone is an OSHA regulated toxic chemical which is 500 times

more toxic than carbon monoxide (CO) that kills hundreds of people

each year. The federal air standard for ozone is only 0.1 ppm while

it is 50 ppm for CO. Ozone attacks mucous membranes, ie the lungs,

and causes chronic respiratory disease.

NIOSH has published that ozone is not very effective in killing

mold or bacteria. Ozone is not " controversial " . It is toxic and

dangerous and not effective in controlling mold or bacteria and

should never be used in a room with people present, even to remove

odors ie smoke damage odors.

Dr. L. Lipsey

Professor and Toxicologist

University of North Florida,

---OSHA HazMat Cert.

U. of Florida Med. Ctr, Jax

Poison Control Center Board

CV--Toxicology And Environmental Health Assoc

From: Dr.Joe Klein <epistrophy1@...>

Date: Sun Jun 1, 2003 4:45 pm

Subject: Re: [] criticism of recent comments on ozone

I am concerned that that some of our visitors may be mislead or

misinformed concerning ozone.

Fact: Ozone can have damaging health effects, especially for

persons with asthma and other lung diseases, children and the

elderly.

Fact: Ozone generators are NOT recommended by the American Lung

Association:

Fact: Much of the material regarding ozone generators makes claims

or draws conclusions without substantiation and sound science.

Fact: EPA does not certify air cleaning devices.

Fact: " Relatively low amounts(of ozone)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. "

Fact: " 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). "

Fact: Exposure to ozone can cause:

1. Decreases in lung function

2. Aggravation of asthma

3. Throat irritation and cough

4. Chest pain and shortness of breath

5. Inflammation of lung tissue

6. Higher susceptibility to respiratory infection

Fact: Ozone is not the same as oxygen and it is not a benign,

harmless, molecule that is safe to breathe in. Ozone is a molecule

composed of an extra atom of oxygen, in addition to the two atoms

which form the basic oxygen molecule that is safe to breathe in.

However, the third oxygen atom can easily detach from the ozone

molecule, and combine with molecules of other substances, thereby

altering their chemical composition. This is how ozone can destroy

lung tissue. The free radical of ozone, combines with vital lung

tissue essentially forming a new substance and thereby destroying

the lung tissue.

Fact: Ozone's damaging effects do not stop once the ozone producing

machine is shut off due to the production of harmful or irritating

by products such as aldehydes and formic acid.

" For many of the chemicals with which ozone does readily react, the

reaction can form a variety of harmful or irritating by-products

(Weschler et al., 1992a, 1992b, 1996; Zhang and Lioy, 1994). For

example, in a laboratory experiment that mixed ozone with chemicals

from new carpet, ozone reduced many of these chemicals, including

those which can produce new carpet odor. However, in the process,

the reaction produced a variety of aldehydes, and the total

concentration of organic chemicals in the air increased rather than

decreased after the introduction of ozone (Weschler, et. al.,

1992b). In addition to aldehydes, ozone may also increase indoor

concentrations of formic acid (Zhang and Lioy, 1994), both of which

can irritate the lungs if produced in sufficient amounts. Some of

the potential by-products produced by ozone's reactions with other

chemicals are themselves very reactive and capable of producing

irritating and corrosive by-products (Weschler and Shields, 1996,

1997a, 1997b). Given the complexity of the chemical reactions that

occur, additional research is needed to more completely understand

the complex interactions of indoor chemicals in the presence of

ozone. "

Fact: Ozone generators do not remove particulate matter from air

which is causes allergy. Furthermore, even if ozone is used in

combination with an " ionizer " it is still not as effective, as a

high efficiency particle filter. This is supported by information

at the EPA web site.

" Ozone does not remove particles (e.g., dust and pollen) from the

air, including the particles that cause most allergies. However,

some ozone generators are manufactured with an " ion generator "

or " ionizer " in the same unit. An ionizer is a device that disperses

negatively (and/or positively) charged ions into the air. These ions

attach to particles in the air giving them a negative (or positive)

charge so that the particles may attach to nearby surfaces such as

walls or furniture, or attach to one another and settle out of the

air. In recent experiments, ionizers were found to be less effective

in removing particles of dust, tobacco smoke, pollen or fungal

spores than either high efficiency particle filters or electrostatic

precipitators. (Shaughnessy et al., 1994; Pierce, et al., 1996).

However, it is apparent from other experiments that the

effectiveness of particle air cleaners, including electrostatic

precipitators, ion generators, or pleated filters varies widely

(U.S. EPA, 1995). "

Fact: " If used at concentrations that do not exceed public health

standards, ozone applied to indoor air does not effectively remove

viruses, bacteria, mold, or other biological pollutants "

Fact: " Whether in its pure form or mixed with other chemicals,

ozone can be harmful to health. "

Fact: The above statements are supported by both The American Lung

Association and The EPA.

Please don't confuse fact with personal testimonials and personal

opinions.

The following has been excerpted from the EPA's web site.

http://www.epa.gov/iaq/pubs/ozonegen.html

" Ozone Generators that are Sold as Air Cleaners: An Assessment of

Effectiveness and Health Consequences "

There is a large body of written material on ozone and the use of

ozone indoors. However, much of this material makes claims or draws

conclusions without substantiation and sound science. In developing

Ozone Generators that are Sold as Air Cleaners, the EPA reviewed a

wide assortment of this literature, including information provided

by a leading manufacturer of ozone generating devices. In keeping

with EPA's policy of insuring that the information it provides is

based on sound science, only peer reviewed, scientifically supported

findings and conclusions were relied upon in developing this

document.

Please Note: EPA does not certify air cleaning devices. The Agency

does not recommend air cleaning devices or manufacturers. If you

need information on specific devices or manufacturers, one resource

you can consult is the Association of Home Appliance Manufacturers

(AHAM) 1111 19th Street, NW, Suite 402, Washington, DC 20036

(202) 872-5955. AHAM also provides information on air cleaners on

their AHAM-certified Clean Air Delivery Rate site at www.cadr.org

Also, the American Lung Association has an Air Cleaning Device fact

sheet at: www.lungusa.org/air/air00_aircleaners.html There are

other resources provided in this fact sheet.

Contents

What is ozone?

How is ozone harmful?

- Ozone Heath Effects and Standards

Is there such a thing as " good ozone, " and " bad ozone " ?

Are ozone generators effective in controlling indoor air pollution?

If I follow manufacturers' directions, can I be harmed?

Why is it difficult to control ozone exposure with an ozone

generator?

Can ozone be used in unoccupied spaces?

What other methods can be used to control indoor air pollution?

Conclusions

Recommendation

Additional Resources

- Publications

- Information Sources

Bibliography

Introduction and Purpose

Ozone generators that are sold as air cleaners intentionally produce

the gas ozone. Often the vendors of ozone generators make statements

and distribute material that lead the public to believe that these

devices are always safe and effective in controlling indoor air

pollution. For almost a century, health professionals have refuted

these claims (Sawyer, et. al 1913; Salls, 1927; Boeniger, 1995;

American Lung Association, 1997; Al-Ahmady, 1997). The purpose of

this document is to provide accurate information regarding the use

of ozone-generating devices in indoor occupied spaces. This

information is based on the most credible scientific evidence

currently available.

Some vendors suggest that these devices have been approved by the

federal government for use in occupied spaces. To the contrary, NO

agency of the federal government has approved these devices for use

in occupied spaces. Because of these claims, and because ozone can

cause health problems at high concentrations, several federal

government agencies have worked in consultation with the U.S.

Environmental Protection Agency to produce this public information

document.

What is 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 to react

with other substances that forms the basis of manufacturers' claims.

How is Ozone Harmful?

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. 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).

Manufacturers and vendors of ozone devices often use misleading

terms to describe ozone. Terms such as " energized oxygen " or " pure

air " suggest that ozone is a healthy kind of oxygen. Ozone is a

toxic gas with vastly different chemical and toxicological

properties from oxygen. Several federal agencies have established

health standards or recommendations to limit human exposure to

ozone. These exposure limits are summarized in Table 1.

Table 1. Ozone Heath Effects and Standards

Health Effects Risk Factors Health Standards*

Potential risk of experiencing:

Decreases in lung function

Aggravation of asthma

Throat irritation and cough

Chest pain and shortness of breath

Inflammation of lung tissue

Higher susceptibility to respiratory infection Factors expected to

increase risk and severity of health effects are:

Increase in ozone air concentration

Greater duration of exposure for some health effects

Activities that raise the breathing rate (e.g., exercise)

Certain pre-existing lung diseases (e.g., asthma)

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) requires

that workers not 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.

The Environmental Protection Agency (EPA)'s National Ambient Air

Quality Standard for ozone is a maximum 8 hour average outdoor

concentration of 0.08 ppm.

(* ppm = parts per million)

Is There Such a Thing as " Good Ozone " and " Bad Ozone " ?

The phrase " good up high - bad nearby " has been used by the U.S.

Environmental Protection Agency (EPA) to make the distinction

between ozone in the upper and lower atmosphere. Ozone in the upper

atmosphere--referred to as " stratospheric ozone " --helps filter out

damaging ultraviolet radiation from the sun. Though ozone in the

stratosphere is protective, ozone in the atmosphere - which is the

air we breathe - can be harmful to the respiratory system. Harmful

levels of ozone can be produced by the interaction of sunlight with

certain chemicals emitted to the environment (e.g., automobile

emissions and chemical emissions of industrial plants). These

harmful concentrations of ozone in the atmosphere are often

accompanied by high concentrations of other pollutants, including

nitrogen dioxide, fine particles, and hydrocarbons. Whether pure or

mixed with other chemicals, ozone can be harmful to health.

Are Ozone Generators Effective in Controlling Indoor Air Pollution?

Available scientific evidence shows that at concentrations that do

not exceed public health standards, ozone has little potential to

remove indoor air contaminants.

Some manufacturers or vendors suggest that ozone will render almost

every chemical contaminant harmless by producing a chemical reaction

whose only by-products are carbon dioxide, oxygen and water. This is

misleading.

First, a review of scientific research shows that, for many of the

chemicals commonly found in indoor environments, the reaction

process with ozone may take months or years (Boeniger, 1995). For

all practical purposes, ozone does not react at all with such

chemicals. And contrary to specific claims by some vendors, ozone

generators are not effective in removing carbon monoxide (Salls,

1927; Shaughnessy et al., 1994) or formaldehyde (Esswein and

Boeniger, 1994).

Second, for many of the chemicals with which ozone does readily

react, the reaction can form a variety of harmful or irritating by-

products (Weschler et al., 1992a, 1992b, 1996; Zhang and Lioy,

1994). For example, in a laboratory experiment that mixed ozone with

chemicals from new carpet, ozone reduced many of these chemicals,

including those which can produce new carpet odor. However, in the

process, the reaction produced a variety of aldehydes, and the total

concentration of organic chemicals in the air increased rather than

decreased after the introduction of ozone (Weschler, et. al.,

1992b). In addition to aldehydes, ozone may also increase indoor

concentrations of formic acid (Zhang and Lioy, 1994), both of which

can irritate the lungs if produced in sufficient amounts. Some of

the potential by-products produced by ozone's reactions with other

chemicals are themselves very reactive and capable of producing

irritating and corrosive by-products (Weschler and Shields, 1996,

1997a, 1997b). Given the complexity of the chemical reactions that

occur, additional research is needed to more completely understand

the complex interactions of indoor chemicals in the presence of

ozone.

Third, ozone does not remove particles (e.g., dust and pollen) from

the air, including the particles that cause most allergies. However,

some ozone generators are manufactured with an " ion generator "

or " ionizer " in the same unit. An ionizer is a device that disperses

negatively (and/or positively) charged ions into the air. These ions

attach to particles in the air giving them a negative (or positive)

charge so that the particles may attach to nearby surfaces such as

walls or furniture, or attach to one another and settle out of the

air. In recent experiments, ionizers were found to be less effective

in removing particles of dust, tobacco smoke, pollen or fungal

spores than either high efficiency particle filters or electrostatic

precipitators. (Shaughnessy et al., 1994; Pierce, et al., 1996).

However, it is apparent from other experiments that the

effectiveness of particle air cleaners, including electrostatic

precipitators, ion generators, or pleated filters varies widely

(U.S. EPA, 1995).

There is evidence to show that at concentrations that do not exceed

public health standards, ozone is not effective at removing many

odor-causing chemicals.

In an experiment designed to produce formaldehyde concentrations

representative of an embalming studio, where formaldehyde is the

main odor producer, ozone showed no effect in reducing formaldehyde

concentration (Esswein and Boeniger, 1994). Other experiments

suggest that body odor may be masked by the smell of ozone but is

not removed by ozone (Witheridge and Yaglou, 1939). Ozone is not

considered useful for odor removal in building ventilation systems

(ASHRAE, 1989).

While there are few scientific studies to support the claim that

ozone effectively removes odors, it is plausible that some odorous

chemicals will react with ozone. For example, in some experiments,

ozone appeared to react readily with certain chemicals, including

some chemicals that contribute to the smell of new carpet (Weschler,

1992b; Zhang and Lioy, 1994). Ozone is also believed to react with

acrolein, one of the many odorous and irritating chemicals found in

secondhand tobacco smoke (US EPA, 1995).

If used at concentrations that do not exceed public health

standards, ozone applied to indoor air does not effectively remove

viruses, bacteria, mold, or other biological pollutants.

Some data suggest that low levels of ozone may reduce airborne

concentrations and inhibit the growth of some biological organisms

while ozone is present, but ozone concentrations would have to be 5 -

10 times higher than public health standards allow before the ozone

could decontaminate the air sufficiently to prevent survival and

regeneration of the organisms once the ozone is removed (Dyas, et

al.,1983; Foarde et al., 1997).

Even at high concentrations, ozone may have no effect on biological

contaminants embedded in porous material such as duct lining or

ceiling tiles (Foarde et al, 1997). In other words, ozone produced

by ozone generators may inhibit the growth of some biological agents

while it is present, but it is unlikely to fully decontaminate the

air unless concentrations are high enough to be a health concern if

people are present. Even with high levels of ozone, contaminants

embedded in porous material may not be affected at all.

If I Follow Manufacturers' Directions, Can I be Harmed?

Results of some controlled studies show that concentrations of ozone

considerably higher than these standards are possible even when a

user follows the manufacturer's operating instructions.

There are many brands and models of ozone generators on the market.

They vary in the amount of ozone they can produce. In many

circumstances, the use of an ozone generator may not result in ozone

concentrations that exceed public health standards. But many factors

affect the indoor concentration of ozone so that under some

conditions ozone concentrations may exceed public health standards.

In one study (Shaughnessy and Oatman, 1991), a large ozone generator

recommended by the manufacturer for spaces " up to 3,000 square

feet, " was placed in a 350 square foot room and run at a high

setting. The ozone in the room quickly reached concentrations that

were exceptionally high--0.50 to 0.80 ppm which is 5-10 times higher

than public health limits (see Table 1).

In an EPA study, several different devices were placed in a home

environment, in various rooms, with doors alternately opened and

closed, and with the central ventilation system fan alternately

turned on and off. The results showed that some ozone generators,

when run at a high setting with interior doors closed, would

frequently produce concentrations of 0.20 - 0.30 ppm. A powerful

unit set on high with the interior doors opened achieved values of

0.12 to 0.20 ppm in adjacent rooms. When units were not run on high,

and interior doors were open, concentrations generally did not

exceed public health standards (US EPA, 1995).

The concentrations reported above were adjusted to exclude that

portion of the ozone concentration brought in from the outdoors.

Indoor concentrations of ozone brought in from outside are typically

0.01- 0.02 ppm, but could be as high as 0.03 - 0.05 ppm (,

1991; U.S. EPA, 1996b; Weschler et al., 1989, 1996; Zhang and Lioy;

1994). If the outdoor portion of ozone were included in the indoor

concentrations reported above, the concentrations inside would have

been correspondingly higher, increasing the risk of excessive ozone

exposure.

None of the studies reported above involved the simultaneous use of

more than one device. The simultaneous use of multiple devices

increases the total ozone output and therefore greatly increases the

risk of excessive ozone exposure.

Why is it Difficult to Control Ozone Exposure with an Ozone

Generator?

The actual concentration of ozone produced by an ozone generator

depends on many factors. Concentrations will be higher if a more

powerful device or more than one device is used, if a device is

placed in a small space rather than a large space, if interior doors

are closed rather than open and, if the room has fewer rather than

more materials and furnishings that adsorb or react with ozone and,

provided that outdoor concentrations of ozone are low, if there is

less rather than more outdoor air ventilation.

The proximity of a person to the ozone generating device can also

affect one's exposure. The concentration is highest at the point

where the ozone exits from the device, and generally decreases as

one moves further away.

Manufacturers and vendors advise users to size the device properly

to the space or spaces in which it is used. Unfortunately, some

manufacturers' recommendations about appropriate sizes for

particular spaces have not been sufficiently precise to guarantee

that ozone concentrations will not exceed public health limits.

Further, some literature distributed by vendors suggests that users

err on the side of operating a more powerful machine than would

normally be appropriate for the intended space, the rationale being

that the user may move in the future, or may want to use the machine

in a larger space later on. Using a more powerful machine increases

the risk of excessive ozone exposure.

Ozone generators typically provide a control setting by which the

ozone output can be adjusted. The ozone output of these devices is

usually not proportional to the control setting. That is, a setting

at medium does not necessarily generate an ozone level that is

halfway between the levels at low and high. The relationship between

the control setting and the output varies considerably among

devices, although most appear to elevate the ozone output much more

than one would expect as the control setting is increased from low

to high. In experiments to date, the high setting in some devices

generated 10 times the level obtained at the medium setting (US EPA,

1995). Manufacturer's instructions on some devices link the control

setting to room size and thus indicate what setting is appropriate

for different room sizes. However, room size is only one factor

affecting ozone levels in the room.

In addition to adjusting the control setting to the size of the

room, users have sometimes been advised to lower the ozone setting

if they can smell the ozone. Unfortunately, the ability to detect

ozone by smell varies considerably from person to person, and one's

ability to smell ozone rapidly deteriorates in the presence of

ozone. While the smell of ozone may indicate that the concentration

is too high, lack of odor does not guarantee that levels are safe.

At least one manufacturer is offering units with an ozone sensor

that turns the ozone generator on and off with the intent of

maintaining ozone concentrations in the space below health

standards. EPA is currently evaluating the effectiveness and

reliability of these sensors, and plans to conduct further research

to improve society's understanding of ozone chemistry indoors. EPA

will report its findings as the results of this research become

available.

Can Ozone be Used in Unoccupied Spaces?

Ozone has been extensively used for water purification, but ozone

chemistry in water is not the same as ozone chemistry in air. High

concentrations of ozone in air, when people are not present, are

sometimes used to help decontaminate an unoccupied space from

certain chemical or biological contaminants or odors (e.g., fire

restoration). However, little is known about the chemical by-

products left behind by these processes (Dunston and Spivak, 1997).

While high concentrations of ozone in air may sometimes be

appropriate in these circumstances, conditions should be

sufficiently controlled to insure that no person or pet becomes

exposed. Ozone can adversely affect indoor plants, and damage

materials such as rubber, electrical wire coatings, and fabrics and

art work containing susceptible dyes and pigments (U.S. EPA, 1996a).

What Other Methods Can Be Used to Control Indoor Air Pollution?

The three most common approaches to reducing indoor air pollution,

in order of effectiveness, are:

Source Control: Eliminate or control the sources of pollution;

Ventilation: Dilute and exhaust pollutants through outdoor air

ventilation, and

Air Cleaning: Remove pollutants through proven air cleaning methods.

Of the three, the first approach -- source control -- is the most

effective. This involves minimizing the use of products and

materials that cause indoor pollution, employing good hygiene

practices to minimize biological contaminants (including the control

of humidity and moisture, and occasional cleaning and disinfection

of wet or moist surfaces), and using good housekeeping practices to

control particles.

The second approach -- outdoor air ventilation -- is also effective

and commonly employed. Ventilation methods include installing an

exhaust fan close to the source of contaminants, increasing outdoor

air flows in mechanical ventilation systems, and opening windows,

especially when pollutant sources are in use.

The third approach -- air cleaning -- is not generally regarded as

sufficient in itself, but is sometimes used to supplement source

control and ventilation. Air filters, electronic particle air

cleaners and ionizers are often used to remove airborne particles,

and gas adsorbing material is sometimes used to remove gaseous

contaminants when source control and ventilation are inadequate.

See Additional Resources section below for more detailed information

about these methods.

Conclusions

Whether in its pure form or mixed with other chemicals, ozone can be

harmful to health.

When inhaled, ozone can damage the lungs. Relatively low amounts of

ozone can cause chest pain, coughing, shortness of breath and,

throat irritation. It may also worsen chronic respiratory diseases

such as asthma as well as compromise the ability of the body to

fight respiratory infections.

Some studies show that ozone concentrations produced by ozone

generators can exceed health standards even when one follows

manufacturer's instructions.

Many factors affect ozone concentrations including the amount of

ozone produced by the machine(s), the size of the indoor space, the

amount of material in the room with which ozone reacts, the outdoor

ozone concentration, and the amount of ventilation. These factors

make it difficult to control the ozone concentration in all

circumstances.

Available scientific evidence shows that, at concentrations that do

not exceed public health standards, ozone is generally ineffective

in controlling indoor air pollution.

The concentration of ozone would have to greatly exceed health

standards to be effective in removing most indoor air contaminants.

In the process of reacting with chemicals indoors, ozone can produce

other chemicals that themselves can be irritating and corrosive.

Recommendation

The public is advised to use proven methods of controlling indoor

air pollution. These methods include eliminating or controlling

pollutant sources, increasing outdoor air ventilation, and using

proven methods of air cleaning.

Additional Resources

Publications:

Copies of EPA's publications are available from the National Service

Center for Environmental Publications (NSCEP)

http://www.epa.gov/ncepihom/ (to order EPA documents online). Use

the EPA Document Number when ordering. Or call 1-800-490-9198/(513)

489-8695 (fax), or write to:

U.S. Environmental Protection Agency

National Center for Environmental Publications (NSCEP)

P.O. Box 42419

Cincinnati, OH 45242

The Inside Story: A Guide to Indoor Air Quality, EPA Document Number

EPA 402-K-93-007. U.S. EPA, U.S. CPSC. April 1995.

Indoor Air Facts No. 7.- Residential Air Cleaners, EPA Document

Number EPA 20A-4-001. U.S. EPA. February 1990.

Residential Air Cleaning Devices: A Summary of Available

Information, EPA Document Number EPA 402-K-96-001. U.S. EPA.

Indoor Air Pollution: An Introduction for Health Professionals, EPA

Document Number EPA 402-R-94-007. American Lung Association, EPA,

CPSC, American Medical Association.

Advisory:

" Health Canada Advises the Public About Air Cleaners Designed to

Intentionally Generate Ozone (Ozone Generators) " , Health Canada,

Canada 1999-19, February 5, 1999.

Information Sources:

U.S. EPA's Indoor Air Quality Information Clearinghouse (IAQ INFO),

PO Box 37133, Washington D.C. 20013-7133; by phone (800) 438-4318.

California Department of Health Services, Indoor Air Quality

Section, Environmental Health Laboratory, 2151 Berkeley Way,

Berkeley, CA 94704; 510-540-3022.

Federal Trade Commission , Consumer Response Center, (202) 326-3128.

U.S. Consumer Product Safety Commission, Washington D.C. 20207; or

call Consumer Hotline, English/Spanish: (800) 638-2772,

Hearing/Speech Impaired: (800) 6388270.

The Association of Home Appliance Manufacturers (AHAM) has developed

an American National Standards Institute (ANSI)-approved standard

for portable air cleaners (ANSI/AHAM Standard AC-1-1988). This

standard may be useful in estimating the effectiveness of portable

air cleaners. Under this standard, room air cleaner effectiveness is

rated by a clean air delivery rate (CADR) for each of three particle

types in indoor air: tobacco smoke, dust, and pollen.

Only a limited number of air cleaners have been certified under this

program at the present time. A complete listing of all current AHAM-

certified room air cleaners and their CADRs can be obtained from

CADR

Association of Home Appliance Manufacturers (AHAM)

1111 19th Street, NW, Suite 402

Washington, DC 20036

(202) 872-5955

AHAM also provides information on air cleaners on their AHAM-

certified Clean Air Delivery Rate site at www.cadr.org

American Lung Association Fact Sheet - Air Cleaining Devices: Types

of Air Cleaning Processes

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The following excerpt is from the American Lung Association:

http://www.lungusa.org/press/envir/asnairc.html

http://www.lungusa.org/bin/search/searchit.pl?

query=Air+Cleaners & ichoice=index.swish-

e & ixname=.swish & results=0 & search.x=9 & search.y=9

OZONE PRODUCTION

Some air cleaners (called ozone generators) use an electrical charge

to generate ozone. Although ozone (also referred to as trivalent

oxygen or saturated oxygen) is a necessary part of the upper

atmosphere (10-30 miles above us), in the part of the atmosphere we

breathe, ozone is a potent lung irritant. It can have damaging

health effects, especially for persons with asthma and other lung

diseases, children and the elderly. It is produced directly by ozone

generators and indirectly by ion generators and some other

electronic air cleaners. The FDA has set a limit of 0.05 parts per

million of ozone in indoor air. Ask whether any electronic air

cleaner you are considering buying has been tested for ozone

production. The American Lung Association suggests that ozone

generators not be used.

ph P. Klein, Sr, M.D.