• You also have to consider very roughly how much wall area is covered with mold, is very large amounts of mold possibly hidden in the walls?

• Is an AC return near your work area that could pull contamination in during removal?

• Are the workers wearing proper protection to prevent something called organic dust  toxic syndrome or other problems?

• Are you sure the workers do not have asthma, or immune system problems?

• Do you have dehumidifiers to dry the interior wall voids?

• And of course has the initial moisture intrusion problem been discovered and repaired?

Most inspectors as well as people suffering with mold problems assume that spores are what make people  sick, but is it possible that mold odor alone without spores can cause health complaints such as but not limited to allergy, asthma, and more frequent colds?

I have done mold inspections since 2003 and have long suspected a direct and strong correlation between mold odor and building occupant health complaints. It seems that mold odor has more to do with health complaints than spore levels in many cases.

It is a well known fact that many manmade volatile organic compounds such as benzene, methyl ethyl ketone, acetone, and formaldehyde to name a few not only have scary names, but can have scary health effects and can contribute to indoor air quality problems such as sick building syndrome and other IAQ problems.

Mold odors are also made of volatile organic compounds. Volatile organic compounds produced by mold include chemicals similar to alcohols, aldehydes, amines, ketones and many more.  When volatile organic compounds are produced by mold or bacteria we stop calling them volatile organic compounds and refer to them as microbial volatile organic compounds.  (mVOCs).

Mold odors or mVOC’s are typically over looked as a source of health complaints by many mold inspectors who look for spores as the only source of potential health problems. Other inspectors are concerned about the health effects of toxins produced by toxic black mold. During many inspections because visible mold was not obvious and the lab report you receive states that spore levels indoors are low,  inspectors will tell you that you do not have a mold problem, and that your health problems are not related to mold in your home.  This inspector has investigated numerous cases where mold odors were produced inside AC units, behind wall paper, in crawl spaces, or inside walls in many such cases spores were trapped or simply not released by the mold and yet people became ill.

After years of noticing this correlation between the occurrence of mold odor and allergy and asthma like health complaints I started to find information on the internet to support these observations.  Please note that the legal and health implications are powerful, even in the lack of elevated spore levels building occupants can still become ill from mold.

Samples of indoor odor can be taken for quantitative and qualitative analysis by accredited labs using proven and advanced methods of analysis, Prism Analytical labs AKA PATI is one of the few labs that specialize in not just voc analysis but also mVOC or microbial volatile compound analysis. 

 Do not rely on my observations, also see what academic and government mold experts say about this often overlooked issue. Do a search for mold odor and health for yourself and you will see that even if spore levels are low in your home there is no guarantee that you are free of mold problems.

But do not despair, there is hope, simply never rely on spore levels and lab tests alone, always hire an experienced inspector who does much more than take samples, he or she should know something  about building construction or home inspections,  AC systems, science, indoor air quality, and industrial hygiene. The mold inspector must do a very detailed investigation using his or her knowledge and experience and should not just take a few samples. 

http://www.florida-mold-inspection.com/

A Accredited Mold Inspection Service, Inc.

The inspector inspected the master bathroom as well as the nearby closets where past leakage occurred through a glass block window.The inspector detected two mild distinct odors in the master bathroom that appeared to be related to microbial growth.One of the odors was the result of mold growing in the duct work that services the master bedroom and master bathroom area.In this inspectors experience the specific moldy odor detected in the bathroom AC ducts is almost always created primarily by a type of mold called Cladosporium spherisperium. This is not a toxic mold and does not produce many spores but it creates musty odors that can cause health complaints. This mold like all AC mold needs two things to survive:1)   food2)   moisture.Food is from dust in your ducts so use a good filter in your AC.Moisture is from humidity drawn in through the AC return so control humidity intake.Your AC return is near the bathroom and as a result this return will allow the AC to pull much humidity in from the bathroom after showers and baths, this is called entrainment and this inspector has seen many AC mold problems resulting from of AC returns near humid bathrooms or in other areas where

SPECIFIC AREA FINDINGS The above mold inspection was conducted in Boca Raton Florida on 1-22-08. The same type of mold odor problem was found 3 weeks later during a mold investigation at a similar luxury home in Wellington Florida near West Palm Beach.   2-12-08 mold inspection  Musty odors were detected, musty or mold odor detection is an important part of any mold investigation because it lets us know that a little mold is present even if it cannot be visually detected. In addition, even when spore levels are low. Minor mold odors were in the following area(s) in the master bedroom when the AC unit was on. The odor detected was typical of that from AC ducts and is not like the odor produced by the many molds that grow in walls. It was detected near the ducts and only when the AC was on.  This was occurring because the AC return is near the master bathroom, this allows the AC to pull humidity into the AC after showers and baths. This humidity condenses in the AC and ducts and allows small amounts of mold to grow in the AC and ducts. This mold inspector has seen this exact same problem in similar homes, and the inspector has seen many mold problems caused under various similar circumstances when AC units pull humidity in, this is called entrainment.  To correct the condition the AC and ducts and main supply plenum for the master bedroom AC will have to be cleaned by a professional who follows NADCA standards and the AC return will have to be moved to a different location in the same zone, a location not so close to the humid bathroom.  Please be aware that this was not a serious mold problem and this does not mean that this is a moldy house, it is a nice house and did not have evidence of a serious mold probelm. This was just your typical minor musty or moldy duct odor and it may not be detected by all persons. Only sensitive persons with allergy or asthma would be affected by such a condition but based on this inspectors experience with this degree of odor some persons can be effects by such odors.

According to current scientific and medical consensus toxic molds do not appear to be poisoning people in their homes because inhalation of spores does not appear likely to expose a person to high enough doses of toxins to cause a toxic reaction. Of course their may be exceptions and this is the current scientific opinion, this information may change in the future.

In animals and in persons living in third world countries toxic mold exposure often has much worse effects than the allergy and asthma type reactions so common in our world. The reasons is that farm animals, like poor starving people in third world countries often have little choice but to eat foods contaminated with toxic mold.

Some important lesson that can be learned from the information contained in the blog is:

1) Be careful to store pet food, farm livestock feed, and other animal foods in appropriate clean places away from mold, moisture, and excessive humidity. I am not a vet or a farmer so I will not telly you how to store animal feed, but keeping foods below 60% RH would likely be a good idea.

2) Take the same precausions you own families food, and never eat foods contaminated with mold or bacteria, unless of course they are suppose to be contaminated with good bacteria or good molds such products are often quite healthy, (Meso soup, soy sauce, blue cheese, cottage cheese, Sauerkraut, Prosciutto ham, beer etc.) This is making me hungry so I will stop with the list of fermented foods.  

3) If you are living in a moldy home, you should not panic over toxic mold, it can likely be remediated and you will likely not have to burn you house down. Contact a properly trained and certified mold testing specialist. Certified indoor environmentalist, and certified industrial hygienist often make the best mold inspectors.

Below is information taken from two trusted web resources, both discuss the effects of the consumption of a specific type of mold toxin (aflotoxin) from a specific toxic mold species (Aspergillius flavus).

In the 1960′s 100,000 turkeys died on farms in England.  The condition was called Turkey X disease .

Later it was found that Turkey X disease was caused by turkey feed made from Brazilian peanuts.

Evidence of acute aflatoxicosis in humans has been reported from many parts of the world , namely the Third World Countries, like Taiwan, Ouganda, India, and many others . The syndrome is characterized by vomiting, abdominal pain, pulmonary edema, convulsions, coma, and death with cerebral edema and fatty involvement of the liver , kidneys , and heart.
Conditions increasing the likelihood of acute aflatoxicosis in humans include limited availability of food, environmental conditions that favor fungal development in crops and commodities, and lack of regulatory systems for aflatoxin monitoring and control.
Because aflatoxins, especially aflatoxin B1, are potent carcinogens in some animals, there is interest in the effects of long-term exposure to low levels of these important mycotoxins on humans .In 1988, the IARC placed aflatoxin B1 on the list of human carcinogens. This is supported by a number of epidemiological studies done in Asia and Africa that have demonstrated a positive association between dietary aflatoxins and Liver Cell Cancer (LCC) .Additionally , the expression of aflatoxin-related diseases in humans may be influenced by factors such as age, sex, nutritional status, and/or concurrent exposure to other causative agents such as viral hepatitis (HBV) or parasite infestation.

http://www.ansci.cornell.edu/plants/toxicagents/aflatoxin/aflatoxin.html

Aflatoxicosis and Aflatoxins

Aflatoxicosis is a disease that can affect many species of fish, and results when feed contaminated with aflatoxins is eaten by the fish (Ashley, 1970). Aflatoxins are chemicals produced by some species of naturally occurring fungi (Aspergillus flavus and Aspergillus parasiticus) commonly known as molds. Aflatoxins are common contaminants of oilseed crops such as cottonseed, peanut meal, and corn. Wheat, sunflower, soybean, fish meal, and nutritionally complete feeds can also be contaminated with aflatoxins.

Four major aflatoxins (AFB1, AFB2, AFG1 and AFG2) are direct contaminants of grains and finished feeds. Factors that increase the production of aflatoxins in feeds include environmental temperatures above 27°C (80°F), humidity levels greater than 62%, and moisture levels in the feed above 14%. The extent of contamination will vary with geographic location, feed storage practices and processing methods. Improper storage is one of the most important factors favoring the growth of aflatoxin-producing molds, and it is a major element that can be controlled by the fish producer.

Implications of Aflatoxins in Fish Feeds

Aflatoxin B1 (AFB1) is one of the most potent, naturally occurring, cancer-causing agents in animals. The first documented incidences of aflatoxicosis affecting fish health occurred in the 1960s in trout hatcheries. Domesticated rainbow trout (Oncorhynchus mykiss) that were fed a pelleted feed prepared with cottonseed meal contaminated with aflatoxins, developed liver tumors (Ashley, 1970). As many as 85% of the fish died in these hatcheries. Although cottonseed meal is no longer used as a major ingredient in feed formulations, poor storage of other feed ingredients and nutritionally complete feeds can lead to contamination with aflatoxins.

Aflatoxicosis is now rare in the rainbow trout industry due to strict regulations enforced by the U.S. Food and Drug Administration (FDA) for aflatoxin screening in oilseeds, corn and other feed ingredients. However, interest in the toxic effects on cultured warm-water fishes, such as tilapia (Oreochromissp.) and channel catfish (Ictalurus punctatus), has increased as diets for these species are now being formulated to contain more plant and less animal ingredients. This increases the potential for development of aflatoxicosis in these species because, as noted earlier, plant ingredients have a higher potential than animal ingredients for contamination with aflatoxins.

In tropical and subtropical conditions, this potential is further increased due to storage under humid and hot conditions. International trade in affected commodities and exposure to aflatoxins are worldwide concerns and the economic impact due to animal losses can be enormous.

http://edis.ifas.ufl.edu/FA095

Daryl Watters is a certified mold inspector, certified home inspector, and certified indoor environmentalist  www.floridamoldinspectors.us www.florida-mold-inspection.com

COMMENT FROM:

Gary Burtle

Good comments on molds and toxins.  Our animals are a barrier between us and these plant-associated toxins.  The subject of fish and aflatoxin is interesting since there is a wide range across fish species for aflatoxin tolerance.  Catfish seem to be 1,000 times more tolerant to aflatoxin B1 than are trout.  Tilapia are also relatively tolerant to aflatoxin.  One study has shown that aflatoxin is eliminated from catfish tissue a day after the catfish quits consuming it.  I would like to see more reserch on peanut, cottoseed, and corn sources of mold toxins related to fish.  The future of aquaculture seems to depend on the development of safe fish feeds.

REPLY FROM BLOG

Occasionally people smell mysterious fish odors in their homes. Often such problems go undiagnosed for several weeks or months before the source of the odor is uncovered. People who are trying to be helpful may suggest that these smells are from dead fish in the yard, or dead rodents in the walls, others may suggest they are the result of sewer gas backing out of your plumbing system, or mold odors resulting from wet building materials. Being a former health inspector, and a current mold inspector and indoor air quality consultant I know that

mold, rodents, and sewer gas do not smell like rotten fish at all. Being lead down the wrong path can be disastrous if the source of fish odor in your home is actually from plastic electrical components heating up in your walls. The following is the summary page from an inspection that was conducted on 7-30-07 at a trailer home in Barefoot Bay Florida North of Vero Beach Florida. Fish odor in the property was from an overheating electrical component. Though the component was only at 130F and not likely to catch fire anytime soon, such conditions should be addressed by a licenses electrical as soon as possible.   The client complained of a odor that comes and goes, the odor appeared to be centered near water damage and decay in the trailer wall of the front bedroom. This damage was investigated and was found to not be producing fish smells, nor excessive mold odors. The client reported that this mystery odor comes and goes and in fact the inspector observed the odor to be very weak at the start of the investigation and it changed in strength a few times. Though odors coming and going sounds strange, but it is common and easily explained. When the sun heats a wall the air in that wall expands and pushes air and any unusual odors that may be present out of the wall, and when the wind blows it creates pressure differentials in the wall that also may force odors out of the wall, in addition an AC unit turning on can pull air out of the wall via it’s AC return. When the inspector smelled around the breaker panel in this room the inspector smelled a mild to strong odor that seemed exactly like dead fish. The client reported that the odor filled the entire room in the past and appeared stronger when the AC unit was turned on.

This condition should be checked by an electrician as soon as possible. This may indicate loose connections in the panel. Warning overheating electrical components can cause house fire. If the odor is not originating in the panel it may be originating from deeper in the plastic conduit that brings the wires to your panel. Have any and all required repairs made soon. The client was warned during the inspection that she should contact an electrician because of the overheating breaker that may be a fire hazard and contact him because of the odor it produces. The client reported to this inspector repeatedly that she would have her electrician check the condition the next day.Additional sampling for volatile organic compounds will probably help this inspector identify the fumes you are breathing such can be done if desired, but getting this condition repaired by an electrician is more important than identification. You may need to have an electrician change the overheating dining room breaker or the entire panel, have this condition corrected properly and soon for safety.

The following is some information that the inspector found on the Internet regarding this condition. It confirms the inspectors findings that overheating electrical components can cause fish odors in homes.  

 

Hello all – My parents are having an issue with a somewhat fishy odor that comes & goes in one area of the house.

We kept smelling a fishy smell and it turned out to be an electrical outlet that was melting inside the wall. The circuit was overloaded (we did not know that). It took the outlet smoking before we figured it out. Since then we smelled that fishy smell again and found another outlet to replace.

• Posted by logic (My Page ) on

  Mon, Jul 17, 06 at 16:39

  On another thread, a “fishy” smell turned out to be melting plastic light covers….the bulbs were too high wattage. I would check everything plastic in the area.

  • Posted by gaffari (My Page ) on

    Tue, Sept 26, 06 at 13:30

     

    Found the source of the smell. Thanks to the posting by LOGIC – I saw that the plastic fixtures (supplied by the builder) were melting. We took them down and they smelled like fish!!!! Thanks for the all the help.

    http://ths.gardenweb.com/forums/load/disaster/msg0511092410993.html

    My apartment has a constant smell of fish in the kitchen but despite cleaning it with every product known to mankind the smell won’t go away.

    This can be an electrical problem. I had an undeniable fish smell in my house. Apparently some wiring (especially in old homes) will give off this smell when it overheats- check your lights and other electrical devices. or better yet call an electrician.

    http://www.apartmenttherapy.com/ny/020706/good-questions/good-questions-fish-smell-mystery-006324

     

    A few weeks back, I wrote into AAC about a fishy odor that was coming from my dining room. This wasn’t a constant smell.

    Well we finally found out what the smell was. One night, around midnight, I was going to bed and turned off the light in the dining room. I could smell that fishy odor again, this time it was not as strong, but I could smell it.

    I went over to the dining room window where the smell was much stronger. I kept smelling around the window until I came to an electrical outlet. As I got closer to the electrical outlet the smell was stronger. I touched the outlet and it was extremely hot. The smell was coming out of the holes.

    We are very fortunate to have had this warning (smell) as you hear families perish from faulty wiring or electrical fires.

    http://ask-a-chick.com/forum/questions_display1.php?question_id=43663

     

    We discovered the smell in my daughter’s room!It is coming from the ceiling light. We were burning a 100W bulb in a max 75W socket and we think it was making the socket smell (must have been plastic getting too hot). Anyway, we left her bedroom light off for 10 days just to be sure….and no more smell.

    from some thread online?

    Thanks a million to those of you who helped us figure out what was causing the fishy smell in our bedroom (we had 100 watt bulbs in 40 watt sockets — whoops).

    http://www.askmehelpdesk.com/other-home-garden/bad-smell-house-comes-goes-49917-2.html

    The clients 2nd concern was possible mold at the dining room ceiling. She reported moisture damage and possible mold at the dining room ceiling, the moisture came from a past roof leak in the area. The client inspected what the client thought was mold and the inspector identified it as insect body parts. No mold or mold odors were found in this area. The attic directly above this area was clean and free of mold odors and visible mold and appeared unlikely to harbor unusual mold conditions. In the photo section the first photo is of the property, the 2nd is of the damaged dining room ceiling covered in plastic, and the 3rd is of the damage in the front guest bedroom.

    ADDITIONAL OBSERVATIONS AND CONCLUSIONSThe inspector detected an extremely slight musty odor in the master bathroom. The inspector inspected under the floor of this bathroom in the crawl space two times and found no evidence of mold or moisture problems just slight musty odors. It appears that slight musty odors were from the moist soil under the trailer and were entering the bathroom through the hole in the bathroom floor where the toilets water supply pipe passes through the floor from the crawl space into the bathroom. Seal the opening where the toilet water supply pipes passes through the floor.

    This inspector cannot inspect for hidden mold deep inside walls or hidden behind vapor barriers or insulation, the crawl space was not fully accessible as it was very small and ducts were in the way. Hidden mold may exist under the bathroom or in the bathroom walls but none was seen. A sample was taken from under the trailer in this odor and no unusual spore levels were found, it is likely that natural molds in the soils are releasing odors and these odors only and not the spores themselves were bypassing the vapor barrier where the sample was taken and then entering the bathroom. Destructive testing involving removal of walls and ducts and vapor barriers that were in the way and obstructing some view can be done if so desired, requested, and paid for.

    The trailers air was dusty as made evident when viewing the air samples and the indoor air was full of outdoor spores as was made evident when the samples were analyzed.

    The filter at the property is a inexpensive boars hair like filter and the client should use a pleated filter or a electrostatic filter to reduce indoor dust. Excessive outdoor spores in the house indicates to much outdoor air infiltrating the house, the house / trailer may be energy inefficient.

    Client should contact an exterminator because of lots of live fire ants in the side wall and under the carpet near the front windows.

 We Service The Following South Florida Counties And Cities:Miami Dade County Florida Mold Inspectors: Aventura, Bal Harbour, Bay Harbor Islands, Biscayne Park, Coconut Grove, Coral Gables, Cutler Ridge, Doral, El Portal, Florida City, Golden Isles, Goulds, Hialeah, Hieleah Gardens, Homestead, Indian Village, Islandia, Kendall, Key Biscayne, Leisure City, Medley, Miami Beach, Miami Gardens, Miami Lakes, Miami Shores Village, Miami Springs, North Bay Village, North Miami, North Miami Beach mold testing inspector, Opa-Locka, Princeton, Richmond Heights, South Miami, South Beach, Star Island, Fischer Island, Sunny Isles Beach, Surfside, Sweetwater, Virginia Gardens, West Miami house mold removal advice, Westchester, Westwood Lake Broward County Florida Mold Inspection, Deerfield, Ft Lauderdale, Lauderdale Lakes, Lauderhill, Hallandale, Pembroke Park, Oakland Park, Miramar, Pembroke Pines, Hollywood, Davie, Plantation, Weston, Fort. Lauderdale, Sunrise, Tamarac, Margate, Cooper City, Coral Springs, Parkland, Pompano toxic mold inspections, Lighthouse Point, Palm Beach County Florida Mold Testing,  West Palm Beach mold testing, Palm Beach, Boca Raton, Delray Beach, Lantana, Lake Worth, Boynton Beach, Wellington, West Palm Beach, Royal Palm Beach, Haverhill, Green Acres, Palm Beach Gardens, Jupiter, Juno Beach, Tequesta, North Palm Beach, Riviera Beach, Singer Island, Loxahatchee, Manalapan, Lake Clark Shores mold inspector, Mangonia Park, Belle Glade, Pahokee, Okeechobee, Indiantown, St Lucie County Mold Inspector, Ft. Pierce, Martin County commercial and residential building investigation help, Stuart, Hobe Sound, Port St Lucie, Jensen Beach Back mold removal help, Palm City, Port Salerno, Hutchinson Island. Monroe County Certified Florida Mold Inspector, Florida keys, Upper Keys, Lower Keys, Middle Keys, Key Largo, Islamorada, Key West.

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I am preparing this information for home owners, realtors, and future potential clients 
who are looking for a mold specialist to answer such questions.

If you have the water extracted and the moisture properly dried out by 
professional remediators or carpet drying specialists in the first 24 to 
48 hours after a leak you may likely be ok. It takes mold a 24 to 48 
hours to start to grow under ideal conditions. As you know carpets get 
moldy very quick, many older carpets with dirt as a food source start 
smelling moldy after being wet just a short time. The above refers to small amounts of mold growth, and the mold may only be at the microscopic levels after a few days. It may be a week or two 
before it grows to the extent that it is visible to the naked eye as spots 
on drywall or carpet pads. Of course, mold being a living organism with it’s own agenda
is not going to follow what I say in this bolg and thus their will be exceptions.

Proper drying is important.
What is most important is how fast and how well the flooded areas are 
dried. Many times a person will think that moisture was removed when in 
fact enough moisture was left behind to allow mold to start growing.
If a minor amount of moisture is lingering inside the wall cavities, behind the baseboards, in 
the carpet, or under the carpet padding it will likely be weeks before it 
all dries up, by that time the mold starts forming as visible sports on your walls.
Many mold remediators and carpet cleaning companies will focus efforts on drying the room that flooded and neglect nearby rooms where water flowed hidden inside wall cavities and under carpet or even tile.
Before you realize that dry out was not done properly you may have white, green, or black mold spots showing
up; you may also detect mold odors and  you will likely have mold
capable of causing allergy or asthma reactions in persons who are prone to 
such reactions.

How to properly dry out a property.
Proper drying often involves discarding wet carpets and carpet pads 
because
they trap moisture and hamper drying. If
the flood was extensive, it may be helpful to remove the baseboards 
because these baseboards can trap water and prevent proper drying; in more 
extreme case a few holes can be cut in the walls to allow wet air to 
escape and dry air to enter the wall cavities.
The use of wet vacs to remove standing water, fans to move air, and 
dehumidifiers to dry the air are helpful. Without dehumidifiers to dry the air you are
simply moving wet air with fans
and this is of little or no benefit. If you can dry your air with 
dehumidifiers and maintain humidity levels between 30%RH and 50%RH it will 
help everything else in the area dry faster. Please be advised that I am not a remediator, we at A Accredited Mold Inspection Service, Inc. provide inspections and written reports on mold and moisture problems for you, your attorney, your buyer, or your insurance adjuster. For more info on proper drying consult with a specialist in remediation or carpet drying etc. 

About mold inspections.
It is best to have a mold inspection done by a mold specialist prior to 
doing any work like removing moldy drywall. A mold 
specialist can try and determine the extent of possible mold spread and 
what needs to be done prior to remediation. If more that a very small problem exists it is recommended that a mold removal specialist be called.
We have no conflict of interest and inspect only. We do not do mold 
removal nor do we provide drying services. The fee is $300.00 to $1000.00 
for a mold inspection in the Miami Ft Lauderdale, and West Palm Beach areas. Prices are likely similar in other areas of the nation. An inspection will also include moisture testing, and a detailed 
inspection and written report. In cases where mold may be hidden behind walls it is almost always very 
important to have some samples taken from inside walls to determine if 
hidden mold is in your walls.  If an inspector tells you they will take 
one or two indoor samples from the center of a few rooms your best course 
of action may be to keep calling inspectors until you find one who knows 
to take samples from inside walls when hidden mold from water intrusion is suspected. 

Daryl Watters is president of A Accredited Mold Inspection Service, Inc. He provides home, mold, and indoor air quality investigations in South Florida. He is also the creator of MIR forms designed to aid inspectors in the production of computer generated indoor air quality and mold inspection reports.

For more inspection information visit http://www.floridamoldinspectors.us/ http://www.florida-mold-inspection.com/
http://www.freemoldinspectionreporting.com/

If the indoor humidity in a building is above 60%RH this may be a concern. If not corrected high humidity can contribute to mold, dust mites, and also condensation problems.

Maintain humidity between 30%RH and 60%RH.

In hot humid climates around the world the reason for humidity problems is not always, but is often related to improper AC use or improper AC design.

1) Holes in the AC closet walls, AC return walls, ceiling, or floors, are extremely common and are often ignored. AC closet holes are often made during construction or AC instillation to provide openings where AC plenums, AC refrigerant lines, condensation drain lines, and wires and wire conduits can pass through. In some climates holes may allow the AC to suck hot humid air in from the attic, crawlspace, or outdoors. When AC units pull in unwanted air we call this entrainment. Any holes in AC closet walls, ceilings, or floors, should be sealed.

2) Thermostats set to the on setting can cause a problem because the on setting causes the AC units blower fan to pull humidity in and distribute it constantly, even when the evaporator coils are not cooling and drying the air brought in by the constantly running AC fan. This is even more of a problem in commercial buildings because most commercial building AC systems are designed to intentionally pull air in from outdoors. In homes where the AC is in the garage, attic, or in an outdoor closet this is also a possible problem because the AC will pull air in through loose panels. The on setting is ok in some areas but in hot humid regions if the fan runs constantly because the thermostat is set to the on setting the amount of humidity drawn in by the AC can be more that the AC is designed to dry.

3) A buildings AC system should not provide more cooling capacity than the building was designed to have. In other words if you have to many AC units or your AC unit is to large for your home or building it can create a problem. Buildings in general should have roughly only one ton of cooling capacity provided by the AC system for each 600 square foot of conditioned area. To much cooling will cool the building and shut down the compressors long before the buildings air has had a chance to dry, thus contributing the the buildings humidity problem.

When humidity is a problem condensation often forms on the AC registers. One of the first places for mold to show up following humidity problems is in the AC ducts, and on the air handler’s blower fan, and insulation. In addition humidity related mold very often grows as small dusty white or green spots of pen asp mold only visible on black clothes and shoes in the closet.

Daryl Watters is president of A Accredited Mold Inspection Service, Inc. He provides home, mold, and indoor air quality investigations in South Florida. He is also the creator of MIR forms designed to aid inspectors in the production of computer generated indoor air quality and mold inspection reports.

For more inspection information visit http://www.floridamoldinspectors.us/ http://www.florida-mold-inspection.com/
http://www.freemoldinspectionreporting.com/

Mold spores from AC ducts result in health problems and even mold odors in the absence of spores have been shown to cause health problems. Keeping ducts free of excessive mold is important.  

The information in this blog is intended to provide readers with information on:

1) Some reasons why AC ducts become moldy.

2) The importance of proper sizing of AC units.

3) In addition it draws attention to a very common indoor air quality problem called entrainment. Entrainment is when AC units pull contaminated air from inside attics or walls or other undesirable areas.

The following information is taken from a Broward County mold inspection we conducted on 11-17-07 it shows an actual example of how ducts became moldy and gives recommendations at the end.

The property inspected is a one story single family Broward county house built in 1974.

Client reported mold growing on AC vent registers. The mold started a few weeks ago. The client reported that a new larger AC unit was installed about 3 months prior to the mold starting. This inspection is for mold conditions at the AC registers only.

Location: Garage:

In the above referenced area the inspector observed a new air conditioner. The serial number on the unit indicates that it is a 4 ton unit, thus is it rated to cool a 2400 sf house. This AC unit is just a little large for this house.

The inspector also observed a new condenser / compressor unit. The serial number indicates that it is a 3.5 ton unit thus designed to cool a 2100 sf house. This is also slightly large for the house.

You have a newer larger AC unit.

The size of this newer AC unit is a major reason for why you have humidity related cladosporium on your AC registers that were previously not moldy.  

The previous AC unit in use about 3 months ago was smaller than this AC system thus would have been more efficient at drying the houses air before cooling the houses air and shutting down. If an AC is to large it shuts off after the air is cooled but before the air is properly dried / dehumidified. Air that is not dehumidified and has a humidity above 60%RH to 65%RH can and often does cause humidity problems in Florida homes.

The above photo is of cladosporium mold growing in your registers.

Another reason why you have mold problems now is because of the two holes in your AC return. These holes in the wall studs allow the AC to pull humidity into the AC each time the AC turns on, this phenomenon is called entrainment and is a common cause of mold and humidity problems.

 Yes all metal studs have these holes, but it is not typical for these open holes in the studs to be exposed and in such close proximity to an AC return.

Where does the humidity in your walls come from? it comes room the attic, the attic in turn gets the humidity from outside via the soffit vents like the one in the above photo.

Why did this problem not occur till recently? the older smaller AC was more efficient at drying air as stated above and thus was able to handle the humidity load created by these openings.

More photos of mold on and around your AC registers. Note that the tiny black spots on and around AC registers are very typical examples of cladosporium spheasperium, or cladosporium cladosporidies mold. This mold problem is caused by elevated humidity in your ducts.

This is not likely to cause a toxic reaction, but this mold may result in allergic reactions or act as an asthma trigger in sensitive persons. The real concern is if it is growing excessively deep in your ducts then you will have much more mold than you can see on the registers.

Mold growth in the ducts can and often causes health complaints.

Excessive mold was not observed in your AC unit but you are recommended to have your ducts cleaned in accordance with NADCA standards or replaced.

More photos of mold on and around your AC registers. Note that the tiny black spots on and around AC registers are very typical examples of cladosporium spheasperium, or cladosporium cladosporidies mold.

Based on this inspectors observations and conclusions your inspector recommends using good quality foil mastic tape or other methods to seal two openings in your AC return wall studs.

Have a AC company install a humidistat and set it to around 50% to 60%RH always maintain indoor humidity between 30% and 60%RH.

Most people live with a little mold in the ducts and have no problems. Mold spore levels in your air was very low. No mold odors were detected. Much of the mold appeared to be primarily in the ends of the ducts just behind the registers.

Have an AC company clean the mold from the registers and from the ends of the ducts just behind the registers.

Duct removal or good professional cleaning in accordance with NADCA standards is recommended if additional hidden mold is discovered inside the ducts during cleaning.

Daryl Watters is president of A Accredited Mold Inspection Service, Inc. He provides home, mold, and indoor air quality investigations in South Florida. He is also the creator of MIR forms designed to aid inspectors in the production of computer generated indoor air quality and mold inspection reports.

For more inspection information visit http://www.floridamoldinspectors.us/ http://www.florida-mold-inspection.com/
http://www.freemoldinspectionreporting.com/