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Knowledge about air duct cleaning is

in its early stages, so a blanket recom-mendation cannot be offered as to whether you should have the air ducts in your homecleaned. The U.S.Environmental Protection Agency (EPA)urges you to read this document in its entiretyas it provides important information on thesubject.

Duct cleaning has never been shownto actually prevent health problems.Neither do studies conclusively demonstratethat particle (e.g., dust) levels in homesincrease because of dirty air ducts. This isbecause much of the dirt in air ducts adheresto duct surfaces and does not necessarilyenter the living space. It is important to keepin mind that dirty air ducts are only one of many possible sources of particles that arepresent in homes. Pollutants that enter thehome both from outdoors and indoor activitiessuch as cooking, cleaning, smoking, or justmoving around can cause greater exposure to

contaminants than dirty air ducts. Moreover,there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to your health.

You should consider having the air ducts in your home cleaned if: There is substantial visible mold growthis present in hard surface (e.g., sheetmetal) ducts or on other components ofyour heating and cooling system. Thereare several important points to understandconcerning mold detection in duct systems:

8 Many sections of your heating and

cooling system may not be accessiblefor a visible inspection, so ask theservice provider to show you any moldthey say exists.

8 You should be aware that although asubstance may look like mold, apositive determination of whether it is mold can be made only by an expertand may require laboratory analysisfor final confirmation. For about $50,some microbiology laboratories cantell you whether a substance sent tothem on a clear strip of sticky house-hold tape is mold or just somethingthat resembles it.

8 If you have insulated air ducts and theinsulation gets wet or moldy it shouldbe removed and replaced as it cannotbe effectively cleaned.

8 If the conditions causing the moldgrowth in the first place are not cor-rected, mold growth will recur.

Ducts are infested with vermin (e.g.,rodents or insects); or

Ducts are clogged with excessiveamounts of dust and debris and/or par-ticles are actually released into the homefrom your supply registers .

If any of the conditions identified above exists, it

usually suggests one or more underlying causes.Prior to any cleaning, retrofitting, or replacing of your ducts, the cause or causes must be corrected or else the problem will likely recur .

Should You Have the Air Ducts in Your Home Cleaned?Summary

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S ome research suggests that clean-ing heating and cooling system compo-nents (e.g., cooling coils, fans and heatexchangers) may improve the efficiency of your system, resulting in a longer operating

life, as well as some energy and maintenancecost savings. However, little evidence existsthat cleaning only the ducts will improve theefficiency of the system.

You may consider having your air ducts cleaned simply because it seemslogical that air ducts will get dirty over timeand should be occasionally cleaned. Pro- vided that the cleaning is done properly , noevidence suggests that such cleaning wouldbe detrimental. EPA does not recommendthat the air ducts be cleaned routinely, butonly as needed. If a service provider or advertiser asserts that EPA recommendsroutine duct cleaning or makes claims aboutits health benefits, you should write EPA (seeaddress at the back of this booklet). EPAdoes, however, recommend that if you have afuel burning furnace, stove or fireplace, theybe inspected for proper functioning andserviced before each heating season toprotect against carbon monoxide poisoning.

If you do decide to have your air ductscleaned, take the same consumer precau-tions you normally would in assessing theservice providers competence and reliability.

Air duct cleaning service providersmay tell you that they need to apply achemical biocide to the inside of your ducts asa means to kill bacteria (germs) and fungi(mold) and prevent future biological growth.They may also propose the application of asealant to prevent dust and dirt particlesfrom being released into the air or to seal air leaks. You should fully understand the prosand cons of permitting application of chemicalbiocides or sealants. While the targeted useof chemical biocides and sealants may beappropriate under specific circumstances,research has not demonstrated their effective-ness in duct cleaning or their potential ad-verse health effects. No chemical biocidesare currently registered by EPA for use ininternally- insulated air duct systems(See page 13) .

Whether or not you decide to havethe air ducts in your home cleaned,preventing water and dirt from enteringthe system is the most effective way toprevent contamination (See page 11) .

C all EPAs IAQINFO at (800) 438-4318 for more information on indoor air quality.

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Table of Contents

Summary .............................................1

What Is Air Duct Cleaning? .................4

Deciding Whether or Not to Have Your Air Ducts Cleaned ...............................6

Suggestions for Choosing a Duct Clean-ing Service Provider ...................8

What to Expect of an Air Duct CleaningService Provider...................................9

How to Determine if the Duct Cleaner Dida Thorough Job ............................9

How to Prevent Duct Contamination...11

Unresolved Issues of DuctCleaning..............................................12

To Learn More About Indoor Air Qualityand Air Duct Cleaning.........................16

Consumer Checklist ...........................17

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What is Air Duct Cleaning?

Most people are now aware that indoor air pollution is an issue of growing concernand increased visibility. Many companies aremarketing products and services intended toimprove the quality of your indoor air. Youhave probably seen an advertisement, re-ceived a coupon in the mail, or been ap-proached directly by a company offering toclean your air ducts as a means of improvingyour homes indoor air quality. These ser-vices typically -- but not always -- range incost from $450 to $1000 per heating andcooling system, depending on the servicesoffered, the size of the system to be cleaned,

system accessibility, climatic region, and levelof contamination.

Duct cleaning generally refers to the cleaningof various heating and cooling system com-ponents of forced air systems, including thesupply and return air ducts and registers,grilles and diffusers, heat exchangers, heat-ing and cooling coils, condensate drain pans(drip pans), fan motor and fan housing, andthe air handling unit housing (See diagram,page 5).

If not properly installed, maintained, andoperated, these components may becomecontaminated with particles of dust, pollen, or other debris. If moisture is present, thepotential for microbiological growth (e.g.,mold) is increased, and spores from suchgrowth may be released into the homes livingspace. Some of these contaminants maycause allergic reactions or other symptoms inpeople if they are exposed to them. If youdecide to have your heating and coolingsystem cleaned, it is important to make surethe service provider agrees to clean all com-ponents of the system and is qualified to doso. Failure to clean a component of a con-taminated system can result in re-contamina-tion of the entire system, thus negating any

potential benefits. Methods of duct cleaningvary, although standards have been estab-lished by industry associations concernedwith air duct cleaning. Typically, a serviceprovider will use specialized tools to dislodge

dirt and other debris in ducts, then vacuumthem out with a high-powered vacuumcleaner.

In addition, the service provider may proposeapplying chemical biocides, designed to killmicrobiological contaminants, to the inside of the duct work and to other system compo-nents. Some service providers may alsosuggest applying chemical treatments (seal-ants or other encapsulants) to seal or cover the inside surfaces of the air ducts and equip-ment housings because they believe thesealant will control mold growth or prevent therelease of dirt particles or fibers from ducts.These practices have yet to be fully re-searched and you should be fully informedbefore deciding to permit the use of bio-cides or sealants in your air ducts. Theyshould only be applied, if at all, after thesystem has been properly cleaned of allvisible dust or debris.

If you decide to have your heating and cooling system cleaned, it is important to make sure the service provider agrees to clean all components of the system and is

qualified to do so.

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Deciding Whether or Not to HaveYour Air Ducts Cleaned

Knowledge about the potential bene-fits and possible problems of air duct

cleaning is limited. Since conditions inevery home are different, it is impossibleto generalize about whether or not air duct cleaning in your home would bebeneficial.

If no one in your household suffers fromallergies or unexplained symptoms or ill-nesses and if, after a visual inspection of theinside of the ducts, you see no indication thatyour air ducts are contaminated with large

deposits of dust or mold (no musty odor or visible mold growth), having your air ductscleaned is probably unnecessary. It is normalfor the return registers to get dusty as dust-laden air is pulled through the grate. Thisdoes not indicate that your air ducts arecontaminated with heavy deposits of dust or debris; the registers can be easily vacuumedor removed and cleaned.

On the other hand, if family members areexperiencing unusual or unexplained symp-toms or illnesses that you think might berelated to your home environment, you shoulddiscuss the situation with your doctor. EPAhas published Indoor Air Quality: An Intro- duction for Health Professionals that can beobtained free of charge by contactingIAQINFO at the number listed in the back of this booklet. You may obtain another freeEPA booklet from IAQINFO entitled The Inside Story: A Guide to Indoor Air Quality for guidance on identifying possible indoor air

quality problems and ways to prevent or fixthem.

You may consider having your air ductscleaned simply because it seems logical thatair ducts will get dirty over time and shouldoccasionally be cleaned. While the debateabout the value of periodic duct cleaning

continues , no evidence suggests that suchcleaning would be detrimental, provided that it is done properly .

On the other hand, if a service provider fails

to follow proper duct cleaning procedures,duct cleaning can cause indoor air problems.For example, an inadequate vacuum collec-tion system can release more dust, dirt, andother contaminants than if you had left theducts alone. A careless or inadequatelytrained service provider can damage your ducts or heating and cooling system, possiblyincreasing your heating and air conditioningcosts or forcing you to undertake difficult andcostly repairs or replacements.

You should consider having the air ducts inyour home cleaned if:

There is substantial visible mold growthinside hard surface (e.g., sheet metal)ducts or on other components of yourheating and cooling system. There areseveral important points to understand con-cerning mold detection in heating and coolingsystems:

8 Many sections of your heating andcooling system may not be accessiblefor a visible inspection, so ask theservice provider to show you any moldthey say exists.

8 You should be aware that although asubstance may look like mold, apositive determination of whether it is mold or not can be made only by anexpert and may require laboratoryanalysis for final confirmation. For about $50, some microbiology labora-tories can tell you whether a samplesent to them on a clear strip of stickyhousehold tape is mold or simply asubstance that resembles it.

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8 If you have insulated air ducts and theinsulation gets wet or moldy, it cannotbe effectively cleaned and should beremoved and replaced.

8 If the conditions causing the moldgrowth in the first place are not cor-rected, mold growth will recur.

Ducts are infested with vermin,(e.g., rodents or insects); or

Ducts are clogged with excessiveamounts of dust and debris and/or par-ticles are actually released into the homefrom your supply registers.

Other Important Considerations...

Duct cleaning has never been shown toactually prevent health problems.Studies have not conclusively demonstratedthat particle (e.g., dust) levels in homesincrease because of dirty air ducts or go downafter cleaning. This is because much of thedirt that may accumulate inside air ductsadheres to duct surfaces and does not neces-sarily enter the living space. It is important to

keep in mind that dirty air ducts are only oneof many possible sources of particles that arepresent in homes. Pollutants that enter thehome both from outdoors and indoor activitiessuch as cooking, cleaning, smoking, or justmoving around can cause greater exposure tocontaminants than dirty air ducts. Moreover,there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to health.

EPA does not recommend that air ductsbe cleaned except on an as-needed

basis because of the continuing uncer-tainty about the benefits of duct cleaningunder most circumstances. If a serviceprovider or advertiser asserts that EPA rec-ommends routine duct cleaning or makes

claims about its health benefits, you shouldnotify EPA by writing to the address listed inthe back of this booklet. EPA does, however,recommend that if you have a fuel burningfurnace, stove, or fireplace, they be inspectedfor proper functioning and serviced beforeeach heating season to protect againstcarbon monoxide poisoning. Some researchalso suggests that cleaning dirty cooling coils,fans, and heat exchangers can improve theefficiency of heating and cooling systems.However, little evidence exists to indicate thatsimply cleaning the duct system will increaseyour systems efficiency.

If you think duct cleaning might be agood idea for your home, but you are notsure, talk to a professional. The companythat services your heating and cooling systemmay be a good source of advice. You mayalso want to contact professional duct clean-ing service providers and ask them about theservices they provide. Remember, they aretrying to sell you a service, so ask questionsand insist on complete and knowledgeableanswers.

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Suggestions for Choosing a DuctCleaning Service Provider

To find companies that provide duct cleaning services, check your Yellow Pages

under duct cleaning or contact the National Air Duct Cleaners Association (NADCA) at theaddress and phone number in the informationsection located at the back of this booklet.Do not assume that all duct cleaning serviceproviders are equally knowledgeable andresponsible. Talk to at least three differentservice providers, and get written estimatesbefore deciding whether to have your ductscleaned. When the service providers come toyour home, ask them to show you the con-

tamination that would justify having your ductscleaned.

Do not hire duct cleaners who makesweeping claims about the health benefitsof duct cleaning -- such claims are unsub-stantiated. Do not hire duct cleaners whorecommend duct cleaning as a routine part of your heating and cooling system mainte-nance. You should also be wary of ductcleaners who claim to be certified by EPA.EPA neither establishes duct cleaningstandards nor certifies, endorses, orapproves duct cleaning companies.

Do not allow the use of chemical bio-cides or sealants unless you fully under-stand the pros and the cons(See page 13).

Check references to be sure othercustomers were satisfied and did notexperience any problems with their heat-ing and cooling system after cleaning.

Contact your county or city office ofconsumer affairs or local Better BusinessBureau to determine if complaints havebeen lodged against any of the companiesyou are considering.

Interview potential serviceproviders to ensure:

8 they are experienced in ductcleaning and have worked onsystems like yours;

8 they will use procedures to protectyou, your pets, and your home fromcontamination; and

8 they comply with NADCAs air duct cleaning standards and, if your ducts are constructed of fiberglass duct board or insulatedinternally with fiberglass duct

liner, with the North AmericanInsulation Manufacturers Associations (NAIMA)recommendations.

Ask the service provider whether theyhold any relevant state licenses. As of 1996, the following states require air ductcleaners to hold special licenses: Arizona,

Arkansas, California, Florida, Georgia, Michi-gan and Texas. Other states may requirethem as well.

If the service provider charges by thehour, request an estimate of the number ofhours or days the job will take, and findout whether there will be interruptions inthe work. Make sure the duct cleaner youchoose will provide a written agreementoutlining the total cost and scope of the jobbefore work begins.

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What to Expect of an Air DuctCleaning Service Provider

If you choose to have your ducts cleaned,the service provider should:

Open access ports or doors to allowthe entire system to be cleaned and in-spected.

Inspect the system before cleaning tobe sure that there are no asbestos-con-taining materials (e.g., insulation, registerboots, etc.) in the heating and coolingsystem. Asbestos-containing materialsrequire specialized procedures and should not

be disturbed or removed except by speciallytrained and equipped contractors.

Use vacuum equipment that exhaustsparticles outside of the home or use onlyhigh-efficiency particle air (HEPA) vacu-uming equipment if the vacuum exhaustsinside the home.

Protect carpet and householdfurnishings during cleaning.

Use well-controlled brushing of ductsurfaces in conjunction with contactvacuum cleaning to dislodge dust andother particles.

Use only soft-bristled brushes forfiberglass duct board and sheet metalducts internally lined with fiberglass.(Although flex duct can also be cleaned usingsoft-bristled brushes, it can be more economi-cal to simply replace accessible flex duct.)

Take care to protect the duct work,including sealing and re-insulating anyaccess holes the service provider mayhave made or used so they are airtight.

Follow NADCAs standards for air ductcleaning and NAIMAs recommendedpractice for ducts containing fiberglasslining or constructed of fiberglass ductboard.

How to Determine if the DuctCleaner Did A Thorough Job

A thorough visual inspection is the bestway to verify the cleanliness of your heating and cooling system. Some serviceproviders use remote photography to docu-ment conditions inside ducts. All portions of the system should be visibly clean; youshould not be able to detect any debris withthe naked eye. Show the checklist on thenext page to the service provider before thework begins. After completing the job, askthe service provider to show you each compo-nent of your system to verify that the job wasperformed satisfactorily.

If you answer No to any of the questions onthe checklist, this may indicate a problem withthe job. Ask your service provider to correctany deficiencies until you can answer yes to

all the questions on the checklist.

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How to Prevent DuctContamination

Whether or not you decide to have the air ducts in your home cleaned, following a

good preventive maintenance program isessential to minimize duct contamination.

To prevent dirt from entering the system:

Use the highest efficiency air filterrecommended by the manufacturer of yourheating and cooling system.

Change filters regularly.

If your filters become clogged, changethem more frequently.

Be sure you do not have any missingfilters and that air cannot bypass filtersthrough gaps around the filter holder.

When having your heating and coolingsystem maintained or checked for otherreasons, be sure to ask the service pro-vider to clean cooling coils and drain

pans.

During construction or renovation workthat produces dust in your home, seal offsupply and return registers and do notoperate the heating and cooling systemuntil after cleaning up the dust.

Remove dust and vacuum your homeregularly. (Use a high efficiency vacuum(HEPA) cleaner or the highest efficiencyfilter bags your vacuum cleaner can take.Vacuuming can increase the amount ofdust in the air during and after vacuumingas well as in your ducts).

If your heating system includes in-ducthumidification equipment, be sure to

operate and maintain the humidifierstrictly as recommended by the manufac-turer.To prevent ducts from becoming wet:

Moisture should not be present in ducts.Controlling moisture is the most effective wayto prevent biological growth in air ducts.Moisture can enter the duct system throughleaks or if the system has been improperlyinstalled or serviced. Research suggests thatcondensation (which occurs when a surfacetemperature is lower than the dew pointtemperature of the surrounding air) on or near cooling coils of air conditioning units is amajor factor in moisture contamination of thesystem. The presence of condensation or high relative humidity is an important indicator of the potential for mold growth on any type of duct. Controlling moisture can often bedifficult, but here are some steps you cantake:

Promptly and properly repair any leaksor water damage.

Pay particular attention to coolingcoils, which are designed to remove water

from the air and can be a major source ofmoisture contamination of the system thatcan lead to mold growth. Make sure thecondensate pan drains properly. Thepresence of substantial standing waterand/or debris indicates a problem requir-ing immediate attention. Check any insula-tion near cooling coils for wet spots.

Make sure ducts are properly sealedand insulated in all non-air-conditionedspaces (e.g., attics and crawl spaces).This will help to prevent moisture due tocondensation from entering the system and isimportant to make the system work as in-tended. To prevent water condensation, theheating and cooling system must be properlyinsulated.

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If you are replacing your air condition-ing system, make sure that the unit is theproper size for your needs and that allducts are sealed at the joints. A unit that istoo big will cycle on and off frequently, result-ing in poor moisture removal, particularly inareas with high humidity. Also make sure thatyour new system is designed to managecondensation effectively.

Unresolved Issues of Duct Clean-ing

Does duct cleaning prevent health problems?

The bottom line is: no one knows. Thereare examples of ducts that have becomebadly contaminated with a variety of materialsthat may pose risks to your health. The ductsystem can serve as a means to distributethese contaminants throughout a home. Inthese cases, duct cleaning may make sense.However, a light amount of household dust inyour air ducts is normal. Duct cleaning is notconsidered to be a necessary part of yearlymaintenance of your heating and coolingsystem, which consists of regular cleaning of drain pans and heating and cooling coils,regular filter changes and yearly inspections

of heating equipment. Research continues inan effort to evaluate the potential benefits of air duct cleaning.

In the meantime...

Educate yourself about duct cleaningby contacting some or all of the sources ofinformation listed at the end of this publi-cation and asking questions of potentialservice providers.

Are duct materials other than bare sheet metal ducts more likely to be contaminated with mold and other biological contaminants?

You may be familiar with air ducts that areconstructed of sheet metal. However,many modern residential air duct systems areconstructed of fiberglass duct board or sheetmetal ducts that are lined on the inside withfiberglass duct liner. Since the early 1970s, asignificant increase in the use of flexible duct,which generally is internally lined with plasticor some other type of material, has occurred.The use of insulated duct material has in-creased due to improved temperature control,energy conservation, and reduced condensa-tion. Internal insulation provides better acous-tical (noise) control. Flexible duct is very low

cost. These products are engineered specifi-cally for use in ducts or as ducts themselves,and are tested in accordance with standardsestablished by Underwriters Laboratories(UL), the American Society for Testing andMaterials (ASTM), and the National FireProtection Association (NFPA). Many insu-lated duct systems have operated for yearswithout supporting significant mold growth.Keeping them reasonably clean and dry isgenerally adequate. However, there is sub-stantial debate about whether porous insula-

tion materials (e.g., fiberglass) are moreprone to microbial contamination than baresheet metal ducts. If enough dirt and mois-ture are permitted to enter the duct system,there may be no significant difference in therate or extent of microbial growth in internallylined or bare sheet metal ducts. However,

Whether or not you decide to have the air ducts in your home cleaned, committing

to a good preventive maintenance program is essential to minimize duct

contamination.

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treatment of mold contamination on baresheet metal is much easier. Cleaning andtreatment with an EPA-registered biocide arepossible. Once fiberglass duct liner is con-taminated with mold, cleaning is not sufficient

to prevent regrowth, and there are no EPA-registered biocides for the treatment of porous duct materials. EPA, NADCA, andNAIMA all recommend the replacement of wetor moldy fiberglass duct material.

In the meantime...

Experts do agree that moisture should not bepresent in ducts and, if moisture and dirt arepresent, the potential exists for biological

contaminants to grow and be distributedthroughout the home. Controlling moisture isthe most effective way to prevent biologicalgrowth in all types of air ducts.

Correct any water leaks or standingwater.

Remove standing water under coolingcoils of air handling units by making surethat drain pans slope toward the drain.

If humidifiers are used, they must beproperly maintained.

Air handling units should be con-structed so that maintenance personnelhave easy, direct access to heat exchangecomponents and drain pans for propercleaning and maintenance.

Fiberglass, or any other insulationmaterial that is wet or visibly moldy (or if

an unacceptable odor is present) shouldbe removed and replaced by a qualifiedheating and cooling system contractor.

Steam cleaning and other methodsinvolving moisture should not be used onany kind of duct work.

Should chemical biocides be applied to the inside of air ducts?

Air duct cleaning service providers may tellyou that they need to apply a chemicalbiocide to the inside of your ducts to killbacteria (germs), and fungi (mold) and pre-vent future biological growth. Some ductcleaning service providers may propose tointroduce ozone to kill biological contami-nants. Ozone is a highly reactive gas that isregulated in the outside air as a lung irritant.However, there remains considerable contro-versy over the necessity and wisdom of introducing chemical biocides or ozone intothe duct work.

Among the possible problems with biocideand ozone application in air ducts:

8 Little research has been conducted todemonstrate the effectiveness of mostbiocides and ozone when used insideducts. Simply spraying or otherwiseintroducing these materials into theoperating duct system may causemuch of the material to be transportedthrough the system and released intoother areas of your home.

8 Some people may react negatively tothe biocide or ozone, causing adversehealth reactions.

Chemical biocides are regulated by EPAunder Federal pesticide law. A product mustbe registered by EPA for a specific use beforeit can be legally used for that purpose. Thespecific use(s) must appear on the pesticide

(e.g., biocide) label, along with other impor-tant information. It is a violation of federal lawto use a pesticide product in any manner inconsistent with its label directions.

A small number of products are currentlyregistered by EPA specifically for use on theinside of bare sheet metal air ducts.

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A number of products are also registered for use as sanitizers on hard surfaces, whichcould include the interior of bare sheet metalducts. While many such products may beused legally inside of unlined ducts if all label

directions are followed , some of the directionson the label may be inappropriate for use inducts. For example, if the directions indicaterinse with water, the added moisture couldstimulate mold growth.

All of the products discussed above areregistered solely for the purpose of sanitizingthe smooth surfaces of unlined (bare) sheet metal ducts . No products are currentlyregistered as biocides for use on fiberglassduct board or fiberglass lined ducts, so it isimportant to determine if sections of your system contain these materials before permit-ting the application of any biocide.

In the meantime...

Before allowing a service provider to use achemical biocide in your duct work, theservice provider should:

Demonstrate visible evidence ofmicrobial growth in your duct work.

Some service providers may attempt toconvince you that your air ducts arecontaminated by demonstrating that themicroorganisms found in your home grow ona settling plate (i.e., petri dish). This is inap-propriate. Some microorganisms are always

present in the air, and some growth on asettling plate is normal. As noted earlier, onlyan expert can positively identify a substanceas biological growth and lab analysis may berequired for final confirmation. Other testing

methods are not reliable.

Explain why biological growth cannotbe removed by physical means, such asbrushing, and further growth prevented bycontrolling moisture.

If you decide to permit the use of abiocide, the service provider should:

Show you the biocide label, which willdescribe its range of approved uses.

Apply the biocide only to un-insulatedareas of the duct system after propercleaning, if necessary to reduce thechances for regrowth of mold followingcleaning.

Always use the product strictly ac-cording to its label instructions.

While some low toxicity products may belegally applied while occupants of the homeare present, you may wish to consider leavingthe premises while the biocide is being ap-plied as an added precaution.

Do sealants prevent the release of dust and dirt particles into the air?

Manufacturers of products marketed tocoat and seal duct surfaces claim thatthese sealants prevent dust and dirt particlesinside air ducts from being released into theair. As with biocides, a sealant is oftenapplied by spraying it into the operating ductsystem. Laboratory tests indicate that materi-als introduced in this manner tend not tocompletely coat the duct surface. Applicationof sealants may also affect the acoustical(noise) and fire retarding characteristics of

No products are currently registered by EPAas biocides for use on fiberglass ductboard or

fiberglass lined ducts so it is important to determine if sections of your system contain

these materials before permitting the application of any biocide.

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fiberglass lined or constructed ducts and mayinvalidate the manufacturers warranty.

Questions about the safety, effectiveness,and overall desirability of sealants remain.

For example, little is known about the poten-tial toxicity of these products under typical useconditions or in the event they catch fire.

In addition, sealants have yet to be evaluatedfor their resistance to deterioration over timewhich could add particles to the duct air.

In the meantime...

Most organizations concerned with ductcleaning, including EPA, NADCA, NAIMA,and the Sheet Metal and Air ConditioningContractors National Association (SMACNA)do not currently recommend the routine useof sealants in any type of duct. Instanceswhen the use of sealants may be appropriateinclude the repair of damaged fiberglassinsulation or when combating fire damagewithin ducts. Sealants should never be usedon wet duct liner, to cover actively growingmold, or to cover debris in the ducts, andshould only be applied after cleaning accord-ing to NADCA or other appropriate guidelinesor standards.

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To Learn More About Indoor AirQuality

U.S. Environmental Protection Agency

World Wide Web Site:http://www.epa.gov/iaq/

Indoor Air Quality Information Clearing-house (IAQINFO)P.O. Box 37133Washington, DC 20013-7133(800) 438-4318FAX: (703) 356-5386

Useful EPA publications available free of

charge from either location above:

8 The Inside Story: A Guide to Indoor Air Quality (EPA 404-K-93-007)

8 Indoor Air Pollution: An Introduc- tion for Health Professionals (EPA 402-R-94-007)

8 Residential Air Cleaning Devices: ASummary of Available Information

(EPA 4001-90-002)

Consumer Research Council (CRC)IAQ ChecklistP.O. Box 12099Washington, DC 20005-0999

Ask for: How Healthy Is The Air In Your Home? (Free. Send a self-addressed,stamped standard size business envelope)

To Learn More About Air DuctCleaning

National Air Duct Cleaners Association

(NADCA)1518 K Street, NW Suite 503Washington, DC 20005(202) 737-2926http://www.nadca.com

Ask for: Introduction to HVAC (Heating,Ventilating, and Air Conditioning) System Cleaning Services (Although intended for commercial custom-

ers, information can be useful to consumers.)

North American InsulationManufacturers Association (NAIMA)44 Canal Center Plaza, Suite 310

Alexandria, VA 22314(703) 684-0084

Ask for: Cleaning Fibrous Glass Insulated Air Duct Systems ; Recommended Practice

Other Useful Resources

For a free list of state and local consumer protection agencies and Better BusinessBureaus:

Consumers Resource Handbook Consumer Information Center Pueblo, CO 81009

For Information on Antimicrobial Biocides:National Antimicrobial Information Net- work (NAIN) (800) 447-6349.Email: nain@ace.orst.edu

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Consumer Checklist

Consider other possible sources of indoor air pollution first if you suspect an indoor air quality problem exists in your home

Learn as much as possible about air ductcleaning by reading this booklet and contact-ing the sources of information provided beforeyou decide to have your ducts cleaned.

Have your air ducts cleaned if they arevisibly contaminated with substantial moldgrowth, pests or vermin, or are clogged withsubstantial deposits of dust or debris.

Get estimates from at least three serviceproviders.

Ask the service provider to show you anymold or other biological contamination theysay exists. Get laboratory confirmation of mold growth or decide to rely on your own

judgement and common sense in evaluatingapparent mold growth.

Find out whether your ducts are made of

sheet metal, flex duct, or constructed of fiberglass duct board or lined with fiberglasssince the methods of cleaning vary dependingon duct type. Remember, a combination of these elements may be present.

Make sure the service provider followsthe National Air Duct Cleaning Associations(NADCA) standards and, if the ducts areconstructed of flex duct, duct board, or linedwith fiberglass, the guidelines of the North

American Insulation Manufacturers Associa-tion (NAIMA).

Ask the service provider whether he/sheholds any relevant state licenses. As of 1996,the following states require air duct cleanersto hold special licenses: Arizona, Arkansas,California, Florida, Georgia, Michigan andTexas. Other states may also requirelicenses.

Insist that the service provider give youknowledgeable and complete answers to your questions.

Check references.

Permit the application of biocides in your ducts only if necessary to control mold growthand only after assuring yourself that theproduct will be applied strictly according tolabel directions. As a precaution, you andyour pets should leave the premises duringapplication.

Do not permit the use of sealants exceptunder unusual circumstances where other

alternatives are not feasible. Follow a preventive maintenance pro-gram of yearly inspections of your heatingand cooling system, regular filter changes,and steps to prevent moisture contamination.