IAQ: Mystery Odor: Occasionally (maybe when our heater kicks on, but not every time?) I smell a chokingly strong odor, very similar to the smell of a hot vacuum cleaner with a full bag where dust seems to be bypassing the filter, plus a little bit of burning dust in a space heater, plus maybe some urine smell. Weirdly, I'm the only one who smells it. Others in the house are unfazed. It goes away after three or so minutes. I've changed the air filter on the heater and we've had the ducts cleaned to no apparent effect. We have had some problems with mice but I haven't noticed a correlation between mouse sightings and the occurrence of the smell. So, 1) Does that sound like any kind of indoor air quality problem you're familiar with? 2) Do you know of any indoor pollutants that only some people are sensitive to, or with an extreme differential in individual sensitivity?
A: Re Q#1; never had this one before (although a significant number of the questions I have gotten are unique.) For Q #2: I think it's unusual for one person to smell something that others can't, but in the world of reactions to mold, some people can walk into a horrific infestation without being bothered, while others are unable to enter the home. It's possible that there is a dead critter in the ductwork. However, the possible association with the furnace raises the possibility (probably remote) that combustion gases are entering the building or ductwork. The two possible mechanisms are 1) Corrosion in the heat exchanger, allowing direct communication between the furnace firebox and the ductwork (this is a potential/inevitable happening at the end of a furnace's lifespan, about 20 or so years). It is hard to overemphasize the importance of CO alarms, especially in houses with aging furnaces (although a well-tuned furnace may not produce a lot of CO). A visual inspection of the firebox/heat exchanger might reveal any corrosion or opened seams in the latter. 2) There is the possibility of backdrafting: When multiple exhaust or vented combustion devices (water heater, clothes dryer) operate simultaneously, if sufficient replacement air is not provided, the resulting vacuum can set up a reverse flow in the weakest appliance, pulling combustion products back in. This can sometimes be detected by holding a piece of tissue paper near the opening of the flue pipe as it exits the appliance. (A small 'puffback' at startup is normal before a robust draft gets established in the chimney.) A partial obstruction in the chimney can also cause backflow of some combustion. For oil-burning equipment, backflows will have a prominent odor of burning oil.
A: First, some basic facts: Radon is a radioactive gas that is colorless and odorless. It seeps out of the ground and can collect in buildings. Its only known health effect is to increase the risk of lung cancer. Radon is present in every state in the country, with some areas having high concentrations of this gas. Radon causes more deaths than any other indoor pollutant. While radon may be distributed throughout the house from the basement by HVAC ductwork (notoriously leaky) especially if the basement is heated, other factors come into play as well. Homes without ducts can have radon problems as well. During the heating season, one important mechanism is thermosiphoning. As warm air rises in the building, it leaks out through the many small openings, cracks, etc characteristic of nearly all buildings. This creates a negative pressure in the lower portions of the building, drawing in outside air and air from the basement since there is typically good communication between the basement and first floor. Thus, radon is distributed to the living space. These negative pressures are also an important driving force to draw any subsurface gases, such as radon, into the building. Other important factors in generating negative pressures in buildings include vented combustion equipment- clothes dryers, hot water heaters, range vent fans and the furnace or boiler, except for 'sealed combustion' units. It is helpful to understand that these driving pressures can be very small-a few pascals are sufficient; likewise very small volumes of radon (on the order of a few cc's per 24 hours) can cause problems. Because of these (and numerous other) variables, radon levels can vary from day to day and hour to hour. Warm climates homes also have radon problems. Check EPA's radon map (State maps are also available.) The most important determinant of radon levels in a building is the geology beneath that building: hot rock beneath-likely high levels above. So there can also be dramatic differences between neighboring houses; thus, each house must be tested. How to communicate radon's importance? This is difficult, for a number of reasons: it's 'natural' and therefore less fearful to some, even though it's radioactive, which usually amplifies the fear factor; and it lacks immediacy-lung cancers take 25-30 years to develop. On the other hand, it is arguably the most lethal of indoor pollutants-18,000 to 22,000 excess US deaths per year (smokers' risks are multiplied by radon exposure); it's easy and inexpensive to test for, and fixing the problem can be readily done for about $1500 to $2000. I tell people that it's like having a smoke detector-while you may not have a problem, you can easily find out if you have a serious problem for only a few dollars. Another concept is that, if there are 'high' levels in your state-30 pCi/l or more-such homes would exceed the OSHA limit for workplace exposures. They would be shut down if they were uranium mines! Wouldn't you want to know this if you were living in such a home? It's easy to find out with a simple and inexpensive test. Your State radon office can provide additional information on radon, both general and local.
Update: The following is a comment from a reader and Dr. Ponessa's response. Since there was mention of a smoke detector and the very commonly installed type has concerning radioactive components, I thought of sharing the information: ATP://ecphoria/radioactive_fire_detectors Thanks for your comment! I really welcome comments and questions relating to my FAQ's and to other housing/environmental issues. Regarding ionization smoke detectors (the most common type), this raises a good point- these contain a small amount of Americium, a radioactive element. However, in the several decades that I have worked on radon issues (and smoke detectors) I have never seen any concern expressed that the use of such detectors poses a health threat in homes. The important take-away message, to the best of my knowledge, is that these devices should be disposed of in a responsible manner. At the end of their 10 year life span (manufacture date is on the back of the detector) I take the detector to my county's hazardous waste center (you might also send them back the the manufacturer-ask first.) Do not discard in a landfill, and do not send to an incinerator. It is difficult to capture (and explain) all of the significant facts about radon in a couple of paragraphs. The concern about smoke detectors brings to mind another fact that provides a valuable perspective: According to the National Council on Radiation Protection report (1987) on exposure of the US population to ionizing radiation, 84% of our exposure comes from natural sources, with about 2/3 of this attributed to radon. Thus, if you are concerned about exposure to radioactivity, you should know that about 54% of our exposure comes from radon. This is a pretty powerful argument to test for radon, and to fix high levels. Another comment, sent privately, stated that my posting suggested that radon problems mainly affect homes with basements. It was pointed out that homes without basements can have radon problems too. This is quite correct, and I apologize for not making this clear; the original questions that I responded to directed attention to basements, and my later posting should have made it clear that homes on slabs can also have serious radon problems. Likewise, homes in warm or tropical climates are also vulnerable to radon intrusion, (I believe this applies primarily to air conditioned, enclosed structures.) Ultimately, the intensity of radon release immediately beneath the building is nearly always the most important determinant of indoor radon levels. Again, thanks for your comments!
High Relative Humidity and Window Condensation: My husband and I live in Montana and we have a small (1300 sq. feet) home and an apartment (700 sq. feet) above our garage we rent out. The apartment is totally new construction, about two years old, and the home has been totally remodeled in the past several years. The problem we are having in both locations is excess moisture in the winter that is ruining our windows. The humidity in the home reads about 46% (on one of those combination clock, temp, humidity devices you buy at a place like Sharper Image); I'm not sure what the humidity is in the apartment. Both the home and the apartment have wood windows that have become so wet that the clear finish has worn off and black mold is growing. In the past, I've taken steps to remove the mold as best I can but it has stained the wood beyond repair. For the past couple of weeks we've left both bathroom fans and the stove fan on all day and that seems to alleviate the moisture a small bit. But we don't want to do this all winter and we don't want to ask our renters to do it either. In the home we are experiencing this mostly on the second floor, where the main bath and our bedroom is; the apartment is on a second floor as well. We've been told that air exchangers are our only option. We've been given the price tag of about $6800 for two of them (that includes the installation and the professional discount we would receive as my husband is a contractor). My questions to you are: Are these exchangers our only option to alleviate the moisture and the window "rot" we are experiencing? Will these exchangers lower the humidity to a more livable level? What do you think of that price? Any feedback would be greatly appreciated.
A: There are multiple aspects to this problem, but it definitely needs to be addressed. In no particular order, here are some thoughts:
1. I presume the humidity reading is correct. Assuming it is an electronic hygrometer, these are pretty reliable, although initial calibration may be off. It would be useful to test it, such as taking it outdoors in a moderate-temperature rainy day & checking for a reading of 100% RH. Alternatively, you could place it in a plastic bag, along with a cup full of water, wait a while, and look for a 100% reading. (I don't know if the device would function properly outdoors in Montana in January, but you would expect to see readings near zero outside on a cold day).
2. The windows should be at least double-glazed (or have a storm window). Triple glazing is probably more suited to MT. At 46% RH and an indoor temp of 70 deg F, condensation will occur on surfaces at about 43 deg F, the dew point for these conditions. So if the window surface temp is 43 degrees or below, condensation will occur.
3 If the hygrometer is wrong and moisture is higher than 46% RH, you need to look for a source of excess moisture. Many sources are obvious, some are not. One big source is unvented combustion. The furnace should be checked for backdrafting. Sometimes in cold climates, the large amounts of moisture in the chimney will freeze as gases cool in the upper parts of the chimney, blocking exhaust. Another cause of high humidity is a humidifier whose control malfunctions, causing it to operate continuously.
4. The ventilation devices-Heat Recovery Ventilators-are generally a good idea, but sound considerably overpriced. They provide ventilation while capturing most heat in the exhaust stream and remove heat from incoming summer air. An alternative would be to install a short duct with a timer control to bring in outdoor air to the return duct of your furnace, assuming that this is an accepted practice in your climate, and assuming that your house is too tight. This will have an energy cost, however.
5. Some possible solutions include: a) adding a plastic storm window (or insulating window treatments) to minimize room air reaching the cold glass surface. Briefly, the expense of doing this relates to appearance; functionally, anything that creates a small airspace from the window-poly film, vinyl or rigid acrylic-will likely solve the problem, but the cheapest will be the ugliest. b) You could also try running a dehumidifier, but this is costly to operate. You might put some effort into reviewing moisture sources in the home, against the possibility that your hygrometer is not accurate; you should be able to find lists of moisture sources in the home on the web, or in your Extension office.
Moisture in Crawl SpaceNote: The original question involved a damp crawl space (location: Delaware) and possible solutions: using a commercial device to suck air from the crawl space, creating a negative pressure there; or sealing off the crawl space and dehumidifying it. It was noted by Dr. Atiles that negative crawl space pressure can draw radon into the crawl space, as well as outside moisture during warm summer months. Dr. Jorge Atiles (Cooperative Extension, University of Georgia) contributed initial information to this discussion, and subsequently forwarded it to Dr. Ponessa. The following Q & A is a follow-up question from the client and Dr. Ponessa's response.Q: I'm going to move forward with a closed crawl space with insulated walls, and a dehumidifier. One concern I have is that dehumidifiers don't operate effectively during cold weather. I was wondering whether anyone studied using a blower to move attic air to a crawl space. I took a few random temp checks at my home and found a temp differential of five degrees between attic and basement on a 50 degree day. It would seem to me that attic air is normally drier than basement air (all the mildew issues appear to be in a crawl or basement environment). Does importing attic air from October through May to a crawl space make any sense?
A: A closed crawl space is generally a good idea for moist, humid (summer) climates, since ventilation during these conditions introduces more moisture than it might remove. However, it is not unusual for unexpected factors to come in to play when applying novel solutions to such problems; therefore, it is important to do regular inspections of affected areas. This will help identify any problems that may not have been anticipated. It might be worthwhile to invest in an electronic hygrometer (available in electronics stores for about $40) to check on moisture levels; generally, these should be no higher that 50-60% RH in conditioned spaces. The problem with basement (or crawl space) dehumidifiers is that, due to the low temps in the basement, their coils may frost up. You can buy models with a defrost cycle, but it may be worthwhile to simply operate a conventional unit for a while, checking regularly for frost. I had used a regular dehumidifier in my own basement, together with a heavy-duty cycling timer that shuts it down for 10 minutes every hour. Three years ago I omitted the timer and have not noticed any problems. A colleague in South Carolina was able, in a one -story rancher, to direct hot air from the attic into his basement to accomplish dehumidification there during the summer. (I doubt that you would see much benefit from October through May.) A large fan was used to push hot attic air into the basement, and he found that operation for just a couple of hours in the afternoon was sufficient. Some precautions: make sure there are abundant openings in the attic for replacement air to enter, and the same in the basement. Any imbalances in air flow can cause pressure differences that can cause problems; e.g., suction in the attic can draw air from the house and, if the AC is on, you lose efficiency and, by drawing outside air into cool rooms, may get condensation on cool indoor surfaces. Pressure or wind in the basement/crawl space may blow out pilot lights if equipment is located there; (suction in basements/crawl spaces may cause backdrafting in flues, as well as bringing in radon.) Be vigilant! AND... first of all: do the easy things to keep moisture out of a crawl space: Cover the soil with 6 mil poly and make sure rainwater does not pond near the foundation. Other tips, mainly for basements, can be found athttp://www.rcre.rutgers.edu/pubs/publication.asp?pid=FS257
Plants and Indoor Air Quality: I work at a school as a para-professional and indoor air quality in the classrooms is always a concern. I read an article about plants in offices and it discussed the fact that some plants can actually improve air quality and it said it got it's information from NASA. Is there a way I can get information on such plants? Which would be the best to use? Do the plants have to be a certain size per square footage? Are the plants harmful at all as far as allergies to touching or ingesting?
A: Some early work was done on this topic in the late 1980's by a Dr. Wolverton and was funded by NASA. He identified certain plants, such as spider plants, golden pothos and several other common houseplants as having the ability to remove formaldehyde and other volatile organic compounds (VOC's) from the air. Subsequently, vendors have been marketing things like indoor greenhouses as air purifying systems, and a trade association had, at one time, hired Dr. Wolverton in an effort to promote this idea. Meanwhile, other researchers have looked into this issue, and Wolverton's data, and concluded that, while this works qualitatively - plants can absorb some VOC's - the numbers don't work out. If a serious VOC problem exists, an impossibly large number of plants would be needed to remedy the problem. Certainly, plants can be a great indoor amenity, and they may provide a small contribution to indoor air quality. The downsides are that: 1) some allergic occupants may be bothered by the plants; and 2) the damp soil may be a breeding ground for mold. Remember too, that virtually all the water provided to a plant is ultimately put into the air by the leaves. So an 'excessive' number of plants can lead to a moisture problem.
A: From the brief description, it sounds like a growth of Poria incrassata (or related species), "The house eating fungus." It's found throughout most of the US, but is particularly common in the southern coastal states & the Pacific coastal areas. There is a pretty good description (although somewhat dated in a few details) in this book chapter: http://entomology.ucr.edu/ebeling/ebel5-2.html Basically, this fungus can grow in a damp crawlspace, often getting its start on wood construction debris left there. The key feature of these molds is that they send out long growths (rhizomes) that can enter walls, extending even to the second floor. The key mechanism is the capability of these growths to convey water (from the earth) along their length, allowing continued growth as wood is consumed. Ultimately, serious structural damage results. The simplest cure is to cut these rhizomes, provided that there are not other sources of water in the walls (such as from condensation or leakage). Some chemical treatments are also effective.
Vapor Barrier & Insulation in Crawlspace: My crawlspace is damp and smells like mildew/mold; it has been this way for a while. We have a high water table in our area. I just received a quote to have a vapor barrier and insulation installed; the crawlspace is 1,000 sq. ft. This quote included 20 mil poly and some type of reflective thermal insulation. The quote was for $6,000. I had another outfit come in to give me a second quote. They are quoting the same work, however, they will be using 6 mil poly. Here are my questions: 1) Does $6,000 sound like it's in the ball park for this kind of work? 2) If mold is present in the crawlspace, what should be done (if anything) before the vapor barrier and insulation are installed? 3) Is 20 mil poly recommended for the vapor barrier, or is 6 mil poly sufficient?
A: For the vapor barrier, 20 mil sounds like overkill. However, this might be appropriate if there is 'traffic' expected in the crawlspace; for example, to service HVAC equipment located there. More customary is 6 or 10 mil, placed on the ground and overlapped 6" or so. The best applications involve carrying the plastic up the foundation walls for about a foot, sealing it to the walls. This strikes me as a lot of extra labor for, probably, a small benefit. In any event, though, this stuff is cheap relative to the labor involved in installation. I don't know much about costs for doing the plastic or installing insulation; getting a couple of bids, for the same specifications, seems like a very good idea. The area involved is, obviously, an important factor. Also important is the headspace available. If it's three feet, installation is a lot easier than if it's 18 inches. The high water table is a tough issue to deal with. If liquid water is regularly seen (and gutters are performing properly, and there is proper grading away from the building) a sump pump might be in order. Local practice can offer some guidance; if neighbors have them, and if they improve things, then this might be part of the solution. But a plastic ground cover (and proper rainwater disposition) are the first steps. If mold is found, it should be removed. This needs to be done safely, by someone who knows what they're doing, so that the rest of the house is not contaminated, and neither workers or occupants are exposed. Killing the mold is not sufficient if there are large areas involved-more than 10-20 sq ft.
Chimney Moisture Problem: I was searching the internet for information on roof leaks and found your article in Home Energy, "Solving a Chimney Moisture Problem". It sounds so similar to my problem. We have a leak coming into the attic from the chimney area. We've waterproofed the fireplace and reflashed the chimney and, still, it is leaking. Our roofer was so puzzled by this it kept him up nights. One chimney company said we needed to cover the fireplace brick (new facade) in order to stop it. We are at our wits end; we've spent so much time and money on this and nothing solves the problem. It seems to be worse in the winter and the roofer seems to think it has something to do with our furnace. We converted to gas when we purchased the house and both the hot water heater and our furnace are vented through the same flue in that chimney. Two years ago, when we were sealing the chimney, we noticed water in the basement near the bottom of flue. Upon inspection, the flue vent tech saw it was damaged and the furnace company came back and replaced it with an aluminum flue. could this still be causing the problem, maybe the flue is not sized properly or maybe both appliances should not be vented together? Can you help in any way? We are really desperate!
A: While I can't absolutely guarantee that this would work, I have recommended the treatment of house odors based on the remediation that is used after a house fire (to get rid of residual smoke odor, after the soot has been physically cleaned): Hire a firm that does fire damage restoration/cleanup to provide an ozone treatment for the house. This is done, of course, while the house is unoccupied. This method is used in hotel rooms also, when a smoker has occupied a non-smoking room. Although ozone is a strong pulmonary irritant, it is a highly reactive chemical that dissipates quickly and should pose no lingering threat. A good airing afterwards should dispose of any byproducts of ozone reactions with volatiles in the home. It would be best to do this treatment in an empty house as much of the odor may have penetrated upholstered & fabric furnishings and the ozone treatment may not be fully effective on the furnishings. I would imagine that the sellers would agree to a contingency in which the transaction would depend on the success of this treatment, to be determined several days after the treatment. While this instance with the curry seems pretty specific, it's applicable to some other odors as well, but not if a quantity of material is embedded in a surface, like, say, cat urine. IMPORTANT NOTE: It cannot be emphasized too strongly that ozone is a potent irritant, and 'consumer' ozone generators, meant to be used in an occupied space, are a bad idea according to EPA and the American Lung Association.
Mold on Down Coats: What I should I do with my winter down coats that were in a closet that has mold. I only saw a strip on the coat about a quarter inch wide and three inches long but I know that there could be mold that is not seen. Should I put them in the dryer for 15 minutes, air them out, wash them? I don't think I should have them dry cleaned as that would expose others.
Testing for Mold: I am 65 years old and have had asthma for the last 20 years! I go to a pulmonologist maybe four times a year and they never seem to find out what's causing me to cough, choke and wheeze, I use asthma medication all year and for some unknown reason I get this upper respiratory infection, post nasal drip, etc. in January and February when my heat is on. I saw a program on Discovery Health last night and this lady had my same symptoms and they found MOLD in her house, hidden behind the walls and under the sink: she was told to never go back in there and in three months she recovered. I need some help in testing and cleaning mold, if I have it, in my home. Where can I go? I have had my ducts cleaned, but didn't see any difference. HELP.
Getting Rid of Roach Smell: I would appreciate some suggestions on how I can get rid of the roach smell in a 16 ft. mobile home I bought. It was infested with roaches when I bought it. They were all over it, including inside the appliances. We thoroughly cleaned the mobile home, washing all the walls and cabinets and even ripped out the carpet and replaced it with wood floors. We painted the sub-floor & ceiling with some kind of paint to seal out odors. We took the kitchen cabinets down and cleaned them completely before rehanging them and we replaced all the appliances. The crawl space was cleaned out and there are no signs of dead roaches any longer. The problem is when the house is closed up the roach smell returns. The county agent suggested there could be remnants of roaches in the walls, but I don't think so. Any suggestions? And yes, we are now wondering why they didn't just buy a new mobile home to place on that lake lot.
Sweating Windows: In the morning my window sills are wet and often have black mold on them, but only when the outside temperature drops below 47 degrees. There are no water leaks around the windows or elsewhere in the house. The windows are at least 14 years old and are double paned. I keep the heat around 70-72 and the humidity is 41%. The problem started to occur last year. I have talked to window professionals who say to replace the windows because the seal between the panes has ruptured. Unfortunately I have no funds to do that; I have pulmonary disease, live on a fixed income and have a mortgage on the house. My thought was to lower the temperature indoors, but that presents some health concerns. Any suggestions for low cost solutions?
Odor from Air Conditioning Ducts (Updated 7/27/2011): What organization(s) can provide consultation and/or services to rid my house of candida (yeast)? I think the stuff is living in the air conditioning system. There's a pervasive smell as of a human yeast infection, but no one in the family has that condition. We first noticed the smell a year ago. It intensifies with the use of AC and diminishes at other times. Now the problem is worse than ever-actually intolerable. We're losing sleep as a result. We've cleaned the house repeatedly, changed AC filters, even sprayed Lysol into the furnace/AC blower. Please advise. By the way, we're very restricted financially, so we'd especially-though not exclusively-appreciate information about low-cost help on this matter.
A: Since you associate the smell with the AC system, the most likely culprit would be the condensate tray beneath the cooling coils of that system. The coil unit is located above or near the furnace, where the return ducts meet with the supply ducts. This part of the system is known as the Plenum. When the warm, moist return air hits the cold coils, condensation occurs and the water falls into the condensate tray. The little tube that drains this tray often gets plugged up, the tray fills with water, and mold colonies form. If you can gain access to view the coils or tray, you should be able to easily confirm mold colonies. I would think a duct cleaning service would be best equipped to tackle this job, provided that they do it in a safe fashion, without stirring up a lot of mold debris that would contaminate the ducts. (Duct cleaners, though, do not usually get into the plenum area.) Those who service your furnace should also be able to do this work, although they may not be skilled in doing it in clean, safe fashion. You might even be able to do this job yourself, if you are able to get access to the tray. The job must be done in such a way that it does not contaminate workers of the surrounding area and ducts. Take a look at the EPA booklet "Mold Remediation in Schools and Commercial Buildings" for vital information on personal protection for those doing the work.Update: A colleague (Ted Funk, Cooperative Extension Specialist, University of Illinois, Urbana.) Added these valuable comments:
1. Such odors from AC systems are often described as a 'dirty sock' smell.
2. The offending mold often grows on the coils themselves.
3. An AC technician would ordinarily be best qualified to clean the coils.
Energy Recovery Ventilator: During one of my home visits I encountered a home where the Energy Recovery Ventilator (ERV) had been unplugged. When I asked the home occupant why it had been disconnected, she stated, "My power bill is less when this is not being used." What might be the consequences (short of a lower power bill) to this home? Are there potential health effects? I noticed there was a ventilation hose connected from the gas supplied furnace to the ERV and also a hose connected from the ERV to an outside vent.
Condensation in Crawl Space: I live in a hot/humid climate and I have a problem with mold/mildew on the floor joists in the crawlspace of my house. The ducts underneath the house are insulated on the outside but they are dripping water. It's a vented crawlspace with the vents open around the house. Unvented crawlspaces are not always an option here in Alabama with high annual rainfalls and often high water tables. It's a house built in 2002 and I've even attempted installing a suction fan to take the humidity out of the crawlspace.
More FEMA Trailer Information: Please tell me what the risk reduction message to a family who is living in a FEMA trailer that was given to the occupants from left-over stock from hurricane Katrina. The home owner was informed that there was known formaldehyde products in the trailer. Are there risk reduction measures that the family can take? If so, what would that be?
Carpet Bleaching in High Traffic Areas: I am on the Board of Directors (Treasurer) at the (apartment building name & location redacted). About three years ago, we had (brand name redacted) carpeting installed on 10 of our 12 floors. A year and a half later, the carpet began to fade, especially in heavy traffic areas. (Brand name redacted) sent a mill inspections service out to look at the carpet and the result of their inspection was this: The pile surface displays a faded orange-ish hue around the elevator and front portions of each hall on most floors. The condition is visible on the carpet base in the same areas and is related to Fume Fading, a topical attack on the dye from atmospheric conditions. The report goes on to say that: the greatest concentrations around elevators doors, trash doors and stairway doors leads us to conclude the source of the contaminant is coming from the lower portion of the building and that the elevator shafts and trash chute act as chimney transports in distributing the affecting contaminants through the building. We need help determining whether this report is accurate. (Brand name redacted) is unwilling to honor their warranty with us and we may be left with the expense of replacing the carpet. If our building is contaminated, we need to have it tested. Please advise me on how I should go about arranging for the testing. Hopefully, you can steer me in the right direction.
Reduction of Formaldehyde in FEMA TrailersNOTE: Media reports in 2009 and 2010 cited high levels of formaldehyde in "Katrina Trailers", temporary housing units that had been hurriedly constructed by FEMA to house displaced residents whose homes had been destroyed by hurricane Katrina. One question below concerned the use of elevated temperatures in affected units to 'bake out' the formaldehyde. (This is a practice sometimes used in new buildings to reduce the levels of volatile indoor pollutants.) A subsequent question asked about the effectiveness of high ventilation rates.Q: Several years ago, I read an article on "baking" an office building to get all the toxic fumes out. As memory serves, the office was vacant, the heat was turned up to about 90 degrees for a period of time and then the office was aggressively ventilated and then the procedure was repeated. This was to remove or reduce the fumes from the carpet and furniture. Maybe this could be a possibility to make these trailers useful and not harmful?
FEMA Trailers: Do you think the trailers could be ventilated with mechanical ventilation that would lower exposure enough? Although the trailers have higher levels than homes, I understand that the recent California study found formaldehyde (among other air toxins) in newer homes and the state is moving towards requiring fresh air make-up in home ventilation systems.
Mold Stains on Siding: I have a putty colored mold growing on the aluminum siding and wood columns of my home. It is in an area that received morning sun and afternoon shade. The mold is like the slime molds that grow on mulch, but it's only on the house. I cleaned it off with a bleach and water solution (the solution was about 50% bleach). Three to five days after washing it off it reappeared. It's Georgia so it has been humid outside. Any suggestions of how to resolve the problem?
Sewage Smell in Basement: Our sewer was worked on this summer and post completion, we noticed a sewage smell in our basement. A technician came to our house and recommended we put bleach down the drain to take away the smell. I contacted a supervisor and here is the response. I mainly want to know whether the recommendation of bleach is sound, and if not, I'd like to provide them with alternative, research-based information, so other families are not given the same response. Here is the email I received: After we received the e-mails below, we started our investigation as to what could possibly be the cause of the sewer smell coming from your basement drain. Our contractor sent a camera down the new lateral that we installed and there are no issues and it is free flowing. The only thing that we can surmise is since your sewer lateral is connected to a 15-inch sewer main, which is a larger sized sewer main, when there is heavy flow in the main that's when you will tend to notice the smell. Now you're obviously asking yourself why didn't I have this problem before the company separated your lateral from your neighbors. We can only speculate why this could be happening. Under your old connection, there was a 6-inch connection with a "Y" at the property line to serve both you and your neighbor. Over time, roots and other build up starts to impede flow from your houses to the main, but in turn it also could act as a buffer not allowing the sewage smell from reaching your house. When the sewer lateral was separated and individual 4-inch connections were installed, this provided both you and your neighbor with brand new, unimpeded sewer connections. As previously stated, due to your connection flowing into an existing 15-inch sewer main, the high volume of sewage flowing through the mainline in the street could be the cause of the smell. As previously stated, this is only speculation since there are no visual issues with the newly installed sewer lateral. The original representative that came to your house suggested that you pour bleach down your drain to help eliminate the smell. We would suggest the same. If you continue to have the same issues, it is possible that there could be issues with the sewer connection on your property, to which you would have to hire a plumber to investigate accordingly.
Yellowish Stains on Bathtub: I need some of your expertise on what causes yellowish stains to appear on a cast iron bathtub after I cleaned it with a cleaner that contained bleach. The stains appeared to be in the areas where the tub had small scratches. I wondered if it could be a reaction of the bleach with the cast iron. I'd like to know how to remove the stains and how to clean the tub in a manner that won't result in the same problem.
Moisture Readings After Flood: I have recently had a clean water flood in my home and in the course of drying it, I cannot find any good data on terminal moisture readings. That is, how low should moisture meter readings be in order to deem the remediation process successful and begin restoration. The drying company engaged by my homeowners insurance carrier packed up and left after four days, but I'm still getting moisture meter readings in excess of 22-24% behind sheetrock at the sill plates. The house is slab-built. I'm also curious about the appropriate protocol for taking moisture meter readings. If the surface of a 2 x 6 appears dry, but an internal reading shows a 24% moisture content, is it OK to begin restoration?
A: I assume that you're taking readings of moisture content with a moisture meter; as I recall, wood at moisture content above about 16% is susceptible to mild growth, although the progress of growth is temperature dependent. If the sheetrock itself is reading 22%, this sounds quite high and I believe there is a serious possibility of mold growth. (Citation: Lstiburek, J. Moisture Control for Buildings. ASHRAE Journal. Feb. 2002. pp 36-41.)
The general recommendation of the Institute of Inspection, Cleaning and Restoration (IICRC, a trade association that sets standards for water damage remediation) is that flooded materials need to be dried out within 48 hours before mold growth gets out of control, although this criterion may be stretched a bit in cooler temperatures. Generally, it is only possible to salvage drywall that has been slightly wetted, but saturated drywall is usually cut out (in increments of 2 feet) to a point above the line of flooding, and replaced after the framing has dried.
Follow-up Comments Regarding Use of Bleach to Kill Mold
I'd like to provide some additional info on the usage of bleach; my response to last week's question involved a very narrow issue and I think it is appropriate to discuss this in a wider context, especially since some groups oppose the use of bleach under all circumstances. This is a somewhat difficult question: to use, or not to use bleach. My opinion is that, while bleach (from the jug) is a pretty potent material that deserves a great deal of respect (i.e. Follow The Directions! Always! Really!) it can be safely used in the appropriate circumstances/rules. Bleach can cause burns to eyes, mucous membranes and other sensitive tissues, and can cause asthma attacks in susceptible persons. While I'm aware that some environmental groups discourage bleach use, I did not find such prohibitions in a quick scan of the websites of the American Lung Association, the EPA or WebMD. From above: The appropriate circumstances/rules for bleach use include:
1. People with asthma or sensitivities to bleach should not use it, and should not be around when it is used.
2. It should not be used around groups of kids, since some might be vulnerable to it.
3. Label directions must be carefully followed-adequate ventilation, dilution and usage according to directions; NEVER use straight bleach. (Dilute bleach may take a few minutes to work, but it's definitely worth waiting.) Dilute as directed-No Cheating!
4. Don't mix with other products: Ammonia, and products containing ammonia compounds, react with bleach to produce a deadly gas similar to the nerve gas used in WW I.
5. Keep bleach containers away from children when it is stored and during use.
With regard to when to use bleach (and when not to) - this is important too. Bleach has two uses- it bleaches/whitens things, removing stains; and it kills germs, mold and other things. BUT, there is a VERY big exception regarding mold-see below. My response last week involved a question about removing mold stains from household items, and I listed some alternatives for items that bleach might damage. In fact, it might have been better for me to have recommended using the weaker products (rubbing alcohol or hydrogen peroxide) first. For laundering, non-chlorine "oxy" type bleaches are available. The MOST IMPORTANT THING to understand about bleach and mold, according to the EPA and others is that for large, thick mold infestations-a few square feet or more-bleach is NOT the way to go. Killing the mold is NOT the right approach, since killed mold spores and debris does not inactivate its harmful properties. The mold should be safely removed (using soap & water) and the moisture problem fixed. Other situations where dilute bleach (sodium hypochlorite) is used for its sterilization property include swimming pools, water wells that have become contaminated, and recovery from "blackwater" flooding after the safe removal of mud, mold and other debris. Blackwater flooding refers to floodwaters that have been contaminated by sewage or floodwaters. This flooding, and all groundwaters are considered to carry silt and harmful organisms, requiring cleaned surfaces to be sterilized as well. (Please be aware that while 'germ killing' is very important in some specific situations-the above mentioned, along with food prep and in consideration of persons with medical vulnerabilities-we as humans are not designed to live in a sterile environment, and have survived since the beginning of time in the presence of microorganisms. In fact, some research indicates that exposure to microorganisms early in life is important for normal development of our immune system which fights infection.)