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Humidifiers Can Cause Mold Problems

Q. I am not sure if I have a mold problem or am creating one by way of our new furnace with built-in humidifier. We installed it last winter and were shocked to see the extreme dampness on all our Andersen windows the next morning after a cold night. The beading water trickled into the corner of every wooden window frame. We are constantly wiping the windows and frames every morning. Our windows (We're talking about a full Florida room with 75% window space and most of the rear of the house-north facing...17 large windows in all) are shaded with honeycomb like shades that can cover the entire window, thus not letting any air out. Also, the dampness from the humidifier has now crept up to the ceiling of every room with a skylight. Those areas of sheetrock are now showing water stains as well and are the reason I'm seeking advice on possible mold damage. Is it impossible to have any working humidifier for a furnace? As it was previously, the winter months provided very dry, choking heat from our old forced hot air system, so we replaced it with the new system/humidifier. But as it is now, we have the humidifier almost turned off completely to avoid further dampness damage. After inspecting the "moldinspector" web site, I see nothing about mold damage from a furnace/humidifier and I am at a bit of a loss to try and find a solution or information about how to proceed? Do I need to do a mold test? [November 29, 2004]

A. Running a built in humidifier, or a portable humidifier, or a vaporizer can significantly increase indoor humidity to make mold a permanent house guest if such humidity inputs are used on a regular basis. Because of the serious threat of mold infestation to family health, you would be wise to never again utilize the humidifier [which may also reduce the value of your home because smart prospective buyers will perceive the existence of the built in humidifier to be a red flag about probably mold contamination in your house]. Because of the heavy window condensation and the evidence of water damage on some of your sheetrock, you need to be concerned about whether your home is now mold contaminated. Your first step is to have the home thoroughly mold inspected and tested with a Certified Mold Inspector or with do it yourself mold test kits. You should also buy a $30 digital hygrometer from a large hardware store, Lowe's or Home Depot to regularly check your indoor humidity year-round in different areas of the house. If the indoor humidity is 60% or more that is going to result in big-time mold problems. Your goal is keep the indoor humidity to 30 to 40% which discourages mold growth. Many homeowners and tenants utilize a programmable dehumidifier to keep the humidity level that mold-safe. Become your own effective mold expert to improve your personal home or apartment environmental safety and/or the environmental health of your investment properties by reading all three of our mold advice, email delivered books [Mold Health Guide, $49; Mold Legal Guide, $49; and Do-It-Best-Yourself Mold Prevention, Inspection, & Remediation, $49, plus Mold Home Mold Remedies special report $25,] for a total of just just $98 [you save $74], the price of only two of these valuable "how to" manuals when you purchase through this special link PayPal or on our online mold products catalog.

Q. My doctor suggested a humidifier for breathing problems. It brought my small apartment from 50% humidity up to about 63%. It had no automatic shut off. I refilled it every 24 hours without emptying the residue and wiping it out with vinegar. I have limited use of my right hand and arm from radiation nerve damage 22 years ago. My thoughts were I would clean it really well at the end of the week. About the sixth day I noticed whitish residue all over everything in the room with the humidifier. I cleaned it and put it away. Not long after that I started getting the sniffles, which seemed to blossom into a full-range chest cold. After coughing up ugly green stuff for a week and it becoming blood-tinged and throat now being sore, I sought advice from my doctor. She could find nothing with her stethoscope and I had no fever - did several tests in her office and some at hospital, the results of which are not in. Since it all continues and glands are now swollen, with a continuing salty taste to any water anywhere, I'm getting anxious about living with the residue I cannot see on my walls, etc. If there is mold there, even if I have everything cleaned by "experts" - will that be enough? Would an ionizer be in the best interest of my future health? If so, which type would you suggest. My space is about 500 sq. feet. {April 25, 2004]

A. An ionizer is worthless for mold problems. You should NEVER use a humidifier if you value your health and possessions. Humidifiers increase humidity [their design goal], enabling mold to grow everywhere, including on all of your possessions, on and inside walls, ceilings, floors, carpeting, and inside heating/cooling equipment and ducts. You need to buy a $30 hygrometer from Home Depot or Lowe's to measure year-round the indoor humidity of all areas of your apartment. Your indoor humidity needs to be at a mold-discouraging 30 to 40%. You may need to operate a programmable dehumidifier set to run automatically, as required, to maintain a desired humidity setting in the 30 to 40% range. In view of your health problems and the likelihood that the residue is you see everywhere is mold, you need to mold test your apartment. Your first mold investigative step is to use our do it yourself mold test kits [self observation of results over a 5 to 7 day time period, or send in for mold lab analysis] to mold test the air of each room, attic, basement, crawl space, and the outward air flow from each heating/cooling duct register for the possible presence of elevated levels of airborne mold spores, in comparison to an outdoor mold control test which you should also do. If you see any visible mold growth, from each moldy area, scrape some of the mold particles into a separate mold test kit per testing location for observation over a 5 to 7 day time period, and/or for mold lab analysis. When scraping mold into a test kit, you would be wise to use a breathing air respirator [Home Depot or Lowe's or a safety store] so that you don't breathe in extra mold spores that you put into the air by scraping some mold-like substances into each mold test kit. The mold test kits come with detailed use instructions to make your tests informative and helpful in mold problem diagnosis. You can also read online our copyrighted form "Self-Analysis & Interpretation of Visible Mold Growth in Do-It-Yourself Mold Test kits." To get more information or to buy the mold test kits, Learn the 25 steps required for safe and effective mold remediation.


The content of this material is neither supported nor opposed by Dr. Schaller for legal reasons. He does thank Phillip Fry for the permission to repost it. You can consult with your local trial lawyer, the medical state board lawyers and your state lawyers in the legislature and judiciary, to see if this is sound medical advice for you. If you think that was fun to write, you are correct. As the son of a brilliant top-flight Pennsylvania OB/GYN, I have seen that the government knows nothing about medicine and about stopping lawsuit abuse. And Pennsylvania is an anti-physician state that only has doctors, because it has a so many medical schools. But that will not help for long.

Many of Phillip Fry's services are available from the hyperlinks underlined products above. Dr. Schaller does feel that 40% humidity is better than 30% to make sure your mucous membranes do not dry out, but he agrees that humidifiers must be used with humidity monitoring so the humidity does not get too high and support mold growth. He also thinks sometimes they can become dirty and allow bacteria to become aerosolized.


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