Facts about Mold and human health

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There is always some mold everywhere – in the air and on many surfaces. Molds have been on the Earth for millions of years. Mold grows where there is moisture.

Mold and Your Health

Exposure to damp and moldy environments may cause a variety of health effects, or none at all. Some people are sensitive to molds. For these people, molds can cause nasal stuffiness, throat irritation, coughing or wheezing, eye irritation, or, in some cases, skin irritation. People with mold allergies may have more severe reactions. Immune-compromised people and people with chronic lung illnesses, such as obstructive lung disease, may get serious infections in their lungs when they are exposed to mold. These people should stay away from areas that are likely to have mold, such as compost piles, cut grass, and wooded areas.

In 2004 the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheeze in otherwise healthy people; with asthma symptoms in people with asthma; and with hypersensitivity pneumonitis in individuals susceptible to that immune-mediated condition. The IOM also found limited or suggestive evidence linking indoor mold exposure and respiratory illness in otherwise healthy children.

In addition, in 2004 the IOM found sufficient evidence to link exposure to damp indoor environments in general to upper respiratory tract symptoms, cough, and wheeze in otherwise healthy people and with asthma symptoms in people with asthma. The IOM also found limited or suggestive evidence linking exposure to damp indoor environments in general to shortness of breath, to respiratory illness in otherwise healthy children and to potential development of asthma in susceptible individuals. In 2009, the World Health Organization issued additional guidance, the WHO Guidelines for Indoor Air Quality: Dampness and Mould[PDF – 2.65 MB]. Other recent studies have suggested a potential link of early mold exposure to development of asthma in some children, particularly among children who may be genetically susceptible to asthma development, and that selected interventions that improve housing conditions can reduce morbidity from asthma and respiratory allergies, but more research is needed in this regard.

A link between other adverse health effects, such as acute idiopathic pulmonary hemorrhage among infants, memory loss, or lethargy, and molds, including the mold Stachybotrys chartarum (Stachybotrys atra), has not been proven. Further studies are needed to find out what causes acute idiopathic hemorrhage and other adverse health effects.

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Mold and Your Home

Mold is found both indoors and outdoors. Mold can enter your home through open doorways, windows, vents, and heating and air conditioning systems. Mold in the air outside can also attach itself to clothing, shoes, bags, and pets can and be carried indoors.

Mold will grow in places with a lot of moisture, such as around leaks in roofs, windows, or pipes, or where there has been flooding. Mold grows well on paper products, cardboard, ceiling tiles, and wood products. Mold can also grow in dust, paints, wallpaper, insulation, drywall, carpet, fabric, and upholstery.

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You Can Control Mold

Inside your home you can control mold growth by:

  • Controlling humidity levels;
  • Promptly fixing leaky roofs, windows, and pipes;
  • Thoroughly cleaning and drying after flooding;
  • Ventilating shower, laundry, and cooking areas.

If mold is growing in your home, you need to clean up the mold and fix the moisture problem. Mold growth can be removed from hard surfaces with commercial products.

Mold growth, which often looks like spots, can be many different colors, and can smell musty. If you can see or smell mold, a health risk may be present. You do not need to know the type of mold growing in your home, and CDC does not recommend or perform routine sampling for molds. No matter what type of mold is present, you should remove it. Since the effect of mold on people can vary greatly, either because of the amount or type of mold, you can not rely on sampling and culturing to know your health risk. Also, good sampling for mold can be expensive, and standards for judging what is and what is not an acceptable quantity of mold have not been set. The best practice is to remove the mold and work to prevent future growth.


  • Keep humidity levels as low as you can—no higher than 50%–all day long. An air conditioner or dehumidifier will help you keep the level low. Bear in mind that humidity levels change over the course of a day with changes in the moisture in the air and the air temperature, so you will need to check the humidity levels more than once a day.
  • Be sure your home has enough ventilation. Use exhaust fans which vent outside your home in the kitchen and bathroom. Make sure your clothes dryer vents outside your home.
  • Fix any leaks in your home’s roof, walls, or plumbing so mold does not have moisture to grow.
  • Clean up and dry out your home thoroughly and quickly (within 24–48 hours) after flooding.
  • Add mold inhibitors to paints before painting.
  • Clean bathrooms with mold-killing products.
  • Remove or replace carpets and upholstery that have been soaked and cannot be dried promptly. Consider not using carpet in rooms or areas like bathrooms or basements that may have a lot of moisture.



Although dust mites are tiny creatures, they can cause big trouble for people who suffer from asthma and allergic reactions. These microscopic bugs share living quarters with humans and animals, feeding on the invisible flakes of dead skin that are shed every day. If a dust mite infestation is not treated properly, it can lead to wheezing, asthma attacks, and other health problems.

This quick guide can help you learn more about the health dangers of dust mites and how you can avoid the ill effects that sometimes come along with them.

Why Are Dust Mites So Common?

In almost every place where humans live and work, you can also find a few dust mites lurking around. You won’t see them, but they’re undoubtedly there. They are tiny bugs, barely a hundredth of an inch in length, looking like tiny specks of dust to the unaided eye. After they feed on small pieces of organic matter, like tiny flakes of dead skin, they produce microscopic particles of waste that can cause severe allergic reactions in sensitive people.

During a life cycle of just a few weeks, each dust mite can produce up to two thousand of these particles. When you combine this with the excellent reproductive capacity of dust mites, you have a recipe for allergies and breathing difficulties. This is precisely why dust mites can be so dangerous to one’s health.

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What Causes the Allergic Reaction?

The waste produced by mites contains a variety of allergens that can trigger sneezing, wheezing, inflamed skin, runny nose, red eyes, and itchiness. If your immune system is sensitive to these allergens, it “misreads” them as disease-causing germs and starts producing antibodies to fight them off.

The resulting chemical reaction causes the various sorts of discomfort associated with dust mite allergies. For people who already suffer from asthma or other respiratory problems, the health risks can be considerably worse.

What Can You Do About Dust Mites?

Dust mites can be rather difficult to eradicate completely. However, there are many ways to keep them under control in your home. Mattresses and bedding materials are the most popular places for dust mites to congregate. Studies of home mattresses have shown that each gram of dust in them can contain more than 2,500 mites!

Although vacuuming is a good way to keep your bedroom looking neat and tidy, it only encourages the dust mites by launching them into the air, giving them even more room to spread out and reproduce. Pesticides, such as disodium tetrahydrate, can be used in powder form to kill-off dust mites, although we would only recommend using these as a last-ditch effort, as the possible side effects associated with pesticides may be rather uncomfortable for you and your family.

6 Ways to “Mite-Proof” Your Home

You can make a variety of smart choices to help keep dust mites away from you and your family. These are some steps you might want to consider taking if you suffer from dust mite-related health problems:

  1. Wash Clothes & Bedding Frequently:
    Be sure to wash all bedding and clothing frequently. Washing in hot water, as well as drying in high heat, will also help kill off any dust mites living within. If you must store unused clothes in your home, keep them clean and wrapped in plastic bags. Remember that dust mites love to feed on flakes of skin and other human waste products. They are not interested in clean fabric.
  2. Protect Yourself With Hypoallergenic Bedding:
    Now that you are frequently washing your bedding, you should consider going a step further and buy hypoallergenic bedding to give an extra layer of protection from dust mites. Because of the fabric’s tightly-woven design and small pore size, it’s nearly impossible for mites and bedbugs to penetrate through the material. Whether you buy a mattress encasement or a pillow cover, this type of bedding is a safe and affordable option to protect yourself from unwanted bed bugs, dust mites, microtoxins and mold.
  3. Keep Humidity Low:
    Dust mites do not like a dry environment. Use a dehumidifier in your home to help keep the moisture levels low. This will not only help you control the dust mite population, but will also hinder the growth of mold.
  4. Get Rid of Carpets:
    When you replace carpets and rugs with hard floor surfaces, the dust mite population will almost certainly drop. They’re easier to clean and create an environment that is less-favorable to dust mites.
  5. Clean Dust With Damp Rag:
    Cleaning all of the dust accumulating around your home is a good idea. However, it’s wise to use a damp rag to do so, as a dry one will stir up dust mites.
  6. Use Natural Feather Bedding:
    It would be wise to use natural feather pillows rather than polyester fiber pillows. Despite some persistent myths to the contrary, scientific studies have shown that dust mites prefer synthetic materials and tend to steer relatively clear of natural fillers.

The Dryer: Your Secret Weapon

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When you invest in fully washable bedding and clothing, you reduce the chances of dust mite infestation. Dryer temperatures of 200°F or higher will annihilate dust mites in a matter of minutes. A related strategy to discourage dust mites is keeping the humidity of your home below 50% whenever possible. Dehumidifiers are very helpful in many home situations. Remember that mites love warm, moist air, but they hate hot, dry air.

Help for Allergic Reactions

If you’re still suffering from breathing difficulties or allergic reactions, there are steps you can take to make yourself more comfortable. A personal air purifier can be placed by your bed or desk, creating a friendly microclimate free of dust mite allergens. Some people find a program of gradual desensitization to be useful in cutting down allergy symptoms. Other people use antihistamines or steroids to manage their reactions. You can consult with your doctor for more information on these various alternatives.

Keep in mind: Dust mites are an unpleasant, but an all too common part of human civilization. Although it is hard to wipe them out entirely, there are many resources available to fight them. With a little planning and strategy, you can avoid much of the discomfort caused by mite infestations, as well as the potentially dangerous health complications that sometimes come along with them.