Mold Exposure Symptoms: Why Mold Could Be Making You Sick Indoors

mold exposure symptoms

Feeling sick at home or in the office?  While a number of factors can contribute to your health indoors, it’s important to rule out if mold is the reason.  How can you know for sure? Consider what mold exposure symptoms or allergies there are and the possible consequences it could have on a person’s health.

How Mold Exposure Affects Each Person Differently

When moisture problems occur and mold growth results, there are different reactions a person can be feeling as a result. For instance, bee stings pose a great risk for persons with a history of allergic reactions. However, others with bee stings may only suffer a minor irritation. The possibility of different levels of mold exposure sensitivity must always be considered when evaluating potential health risks.

All molds have the potential to cause health effects. Through the production of allergens, irritants, and perhaps toxins, molds can affect the wellbeing of building occupants and remediation workers. This is another reason why reactions from individuals exposed to mold and the severity they are subjected to can vary. It’s based on the types and concentrations of molds present, the duration of the exposure and the sensitivity and age of the individual(s) exposed.

Symptoms of Mold Exposure

As noted before, indicators that someone is being subjected to mold can vary by individual. An occupant may report odors, allergies or a variety of other health problems.

Signs from exposure can be set off by breathing in microbial spores or by skin contact with mold when the person has an increased level of sensitivity. Reactions can be immediate or delayed. Here are common mold exposure symptoms to look for:

  • breathing difficulties
  • headaches
  • fever
  • allergic reactions
  • runny nose, coughing and sneezing
  • red and/or burning eyes
  • chronic fatigue
  • skin rashes
  • aggravated asthma symptoms

In extreme cases, life-threatening reactions such as anaphylactic shock have been reported. Repeated or even a single exposure to a sufficiently high concentration of mold may cause a previously non-sensitive individual to become sensitive. The more prolonged the exposure, the greater the risk of developing allergic sensitivity. Microbial spores and cell fragments may be capable of producing allergic reactions whether the molds are dead or alive (viable).

Who is Most At Risk To Mold Exposure?

There are certain groups that are commonly considered to be higher-risk populations for mold sickness. Persons with compromised immune systems, the elderly, young children, people with respiratory sensitivities and those with chronic exposure may all be at greater risk for developing symptoms than healthy adults or those with limited exposure.

Mold exposure can even trigger attacks for those with asthma. The irritants produced by molds may also worsen asthma in non-allergic (non-sensitized) people. Hypersensitivity Pneumonitis, a chronic disease that resembles pneumonia, may develop during either a short, acute exposure or as a result of chronic exposure to low or moderate levels of mold.

Persons with compromised immune systems may fall prey to opportunistic infections as a result of their body’s inability to protect itself against common mold exposures. Because of their compromised immune system, they are much more susceptible to these types of mold infections. Aspergillus fumigatus and Trichoderma, among many others, have been identified as species of molds that can cause opportunistic infections in immune-compromised adults and children. Even for healthy individuals, massive or prolonged mold exposure can certainly increase the chance of infection.

Why Mold Can Thrive Indoors

The outside air almost always has mold. Most people do not have extreme reactions to exposure outdoors. This leads some to erroneously assume that exposure to mold in buildings should be of no greater concern than those outside. However, mold exposure inside is generally both quantitatively and qualitatively different.

The indoor environment is quite different from those outside. Thus, certain molds have a competitive advantage, with species that are rare outside often dominant inside. Unfortunately, many of the types of molds that often grow inside buildings are “species of concern.” These are molds that have been associated with health effects in humans.

Mold spores growing outdoors tend to disperse when released into the air. People in the vicinity rarely become exposed to such mold. However, the setting changes when molds grow inside buildings. The released spores and other particles tend to become trapped. As a result, the spores are able to build up to concentrations rarely if ever seen outside.

For example, in Florida total mold spore concentrations outside are often in the range of 500 to 5000 per cubic meter of air, m3. Although outside concentrations may often go much higher, 50,000/m3 or more, such concentrations tend to be transient. By contrast, accumulation in moldy buildings may sometimes be as high as 500,000/m3 or even considerably higher. To make matters worse, these levels do not disperse and may remain at such high concentration for long periods, exposing occupants to doses (exposure x duration) that would never be found outdoors. And this unfortunately leads to an increase of occupants feeling sick due to mold allergy symptoms in their home or at work.


What if the mold exposure symptoms discussed above appear to fit your situation? Do you also notice other signs in your home, like a musty odor or water damage?  It would then be prudent on your part to contact a mold professional so they can provide the guidance on what to do next.

Related Topic: Mold Growth and Mold Remediation in Buildings


IET’s mold inspection services are provided in the entire Tampa Bay area and Florida.  If in need of any of our indoor environmental services, please contact us today.


  1. Julia says:

    I suffer from severe mold related allergic reactions. Effective cleaning of all rooms in the house is an absolute must, but getting a highly rated air purifier I would say is also required.

  2. Rena Smith says:

    I am totally agreed with Julia. One of cousin recently suffering from mold allergic reaction and my mum just bought him an air purifier with hepa filter. After one week, he feels a lot better.

  3. IET says:

    I agree with both Julia and Rena. High-efficiency filtration of the HVAC system, using deep-pleat filter systems located immediately before the air handler such as those made by Aprilaire, is one of the most effective ways to reduce particles in the air of the home. IET is a dealer for IQAir air purifiers, which we think are among the best available.


    Tim Toburen
    Environmental Consultant

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