How to Detect Mold Spores

Updated July 20, 2017

Mold spores not only grow visibly on furniture and walls, but they also can circulate in the air: both inside and outside. Detection and testing for mould spores is important to the safety of a home or building. All mould, including the mould spores released into the air by mould, are a health hazard. In particular, stachybotrys mould spores release a poisonous toxin called mycotoxin, which is dangerous to human health. If mould is suspected, testing is necessary. If mould is found, careful removal should be done by a professional or by following the guidelines of the Environmental Protection Agency.

Put on protective gear: a N-95 respirator, gloves extending to the middle of the forearm, and a pair of goggles, preferably without ventilation holes.

Peel up the corners of carpeting where water or moisture has accumulated. Check for mould on the bottom.

Look in moist areas, such as the kitchen and bathroom, for signs of mould. Check the bottom of cabinets, under the cabinets and on the floor.

Peel a corner of wallpaper back to check for mould spores growing on the wall or on the wallpaper. If water damage has occurred, it is advisable to open the wall and check for mould behind and in the drywall.

Check the air conditioning and furnace units for stagnant water that may be growing mould. Also check the duct systems for condensation and mould.

Check in the basement for signs of mould, particularly around plumbing, sinks and the washing machine.

Buy two mould testing kits. Depending on how much detail you want in the test results, test kits can run between £6 and £61.

Test the inside air. Follow the instructions on the kit you purchased.

Test the outside air, again following the instructions on the kit you purchased. Testing the outside air is important so that a comparison to the inside air can be made.

Analyse the results. The National Allergy Bureau claims that a mould count of 0 to 900 mould spores per cubic meter is low, 901 to 2,500 is moderate, 2,501 to 25,000 is high, and anything above 25,000 is very high. The American Conference of Government Industrial Hygienists recommends that when indoor mould levels are greater than one third the outdoor level, the building has mould problems that need to be addressed. Air testing can be unreliable and fluctuate widely, so it is best to consult with a professional.


Air testing can be affected by the opening and shutting of doors and windows, as well as by lights being on or off. For more accurate results, consult a professional.


If mould is not visible but you suspect a high concentration of mould spores, it is best to let a professional do the checking or to wear protective gear. Otherwise, opening a wall or peeling up a carpet could release thousands of mould spores into the air. Cleanup is best done by a professional, as well. Mold spores are toxic and dangerous to health.

Things You'll Need

  • 2 mould testing kits
  • N-95 respirator
  • Long gloves
  • Goggles
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About the Author

Jennifer Collins has been writing both fiction and non-fiction since 2001. She's written several pop-culture essays published in "Perfectly Plum" and "Ardeur." Before her writing career, Collins was a pianist and teacher who did her undergraduate and graduate studies at the Cleveland Institute of Music, majoring in piano performance.