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Can outdoor mold make me sick ?


Can outdoor molds make me sick?

Outdoor molds can and do cause health problems. According to Harriett Burge mother of indoor air quality a condition sometimes called thunderstorm fever is caused by exposure to basidospores during thunderstorms. Basidiospores are spores produced by mushrooms, wood decay fungi, and other related outdoor molds.

These molds produce a rotten wood or mushroom-type odor and are often found in moist soil, dead wood, or in moist mulch. This mold inspector has seen these molds first-hand with the aid of a microscope, and these spore levels do in fact increase dramatically during, before, and after, heavy rains. In this mold inspector's experience, Ascospores, Cladosporium spores, and pen asp spores also increased in numbers around the time of storms.

Other similar problems occur with exposure to elevated outdoor mold spore levels. This has been documented in Louisiana after Hurricane Katrina flooded most of New Orleans. Mold spores like pollen can cause health reactions when at high levels outdoors.

Large amounts of mold growing in large amounts of soil and in large amounts of decaying organic matter, such as is found in large compost piles or in landfills, can cause a serious reaction.     

Do not panic if you have a black mold growing on your bushes, trees, sidewalk, ttile roof, or exterior walls. This mold is typically common outdoor black sooty mold ( Aerobisidum, Cladosporium spherisperium, and other molds as well as some green algae). This type of mold is common on exterior shady walls in wet climates such as Florida and the Southeast. This inspector has not seen a likely correlation between this mold and health complaints. I have seen it even during many Miami Beach and Palm Beach mold inspections on or around the nicest homes.  

It is one thing to have miles upon miles of soil filled with decaying organic matter and mold to release thousands of spores per cubic meter of air when triggered to do so by atmospheric changes that occur during a massive storm. Or to have mold in a massive landfill with tons of decaying trash cause mold problems.     

It is another thing to have unsightly mold growing on your exterior walls and trees. Often the mold growing on your walls is not in significant enough amounts to have an effect on surrounding air spore levels when it is diluted by the outdoor air.

I cannot speak for every outdoor sooty mold problem, and exceptions must exist for example if you have large enough amounts of sooty mold on your exterior walls and some pathway such as an open window that allows these mold spores to get into your house, then I suppose you could have a reaction. If it is on your lawn furniture and you sit on that moldy furniture it seems that a skin reaction is possible. I have seen several people with rashes that their doctors diagnoses as being the result of mold, but all these people had humidity mold on their clothes. But in many cases, as a general rule, outdoor mold on your walls and bushes is like some rude persons urinateing in a swimming pool. By the time the stuff gets to you, it is diluted and will likely not harm you.    

Of course I am not a doctor, for medical advice you should consult a doctor not some guy on the internet.      

Much of the time sooty mold does not appear to release spores as readily as many indoor molds that inspectors encounter. In fact, an air sample from the yard that has very much of this sooty mold will typically not show much of the specific spores produced by sooty molds.

In addition, many times sooty mold does not typically produce large amounts of unhealthy smelly by-products known as MVOCs.


When studying this mold using reliable university and government websites, this mold inspector has found no information in regard to this mold being a likely health threat. It is more of a cosmetic problem.

If you really feel that mold outside your house is making you sick, do not hesitate to contact a doctor and a local Certified Indoor Environmentalist, Certified State Mold Assessor, or Certified Industrial Hygienist who holds required mold licenses. 

Please visit our mold testing and inspection website at http://floridamoldinspectors.us