09 Sep , 2021

Moulds can be a health hazard in buildings that are already built or under construction. Some moulds are toxic. Touching them—or breathing in their spores—can be harmful. Symptoms include:

  • ·         Irritated skin, eyes, nose, and throat
  • ·         Runny nose and watery eyes
  • ·         Trouble breathing
  • ·         Fatigue and headaches.

People allergic to moulds may get nosebleeds and a severe cough. If your immune system is weak, you should not work in mould-contaminated areas.

Not everyone exposed to toxic moulds will develop symptoms.


Moulds are colourful and woolly. They can be almost any colour—red, blue, brown, green, white, or black. They reproduce by releasing spores into the air. More mould may grow where the spores land.


Mould thrives on cellulose material that is wet, or water soaked. This includes drywall, ceiling tiles, wallpaper, particleboard, insulation, and plywood. Moulds love dark, moist places and can grow at room temperature. Mould can appear on damp materials in as little as 48 hours. Mould has been found in portable classrooms with moisture problems. This is usually a black mould that looks slimy.

You may be exposed to moulds when you work in damp locations or water-damaged buildings.

Visible mould may be just the tip of the iceberg. More mould may be growing out of sight behind walls, under floors and carpets, and above ceilings in a ventilation system.

If you find mouldy areas on a job, tell your supervisor. The company may arrange to have tests done. Samples must be taken and analyzed to see whether the mould is dangerous.

Toxic moulds must be removed. There is no way to work around them. Removal calls for special procedures, including protective equipment such as respirators, coveralls, and gloves.

If mould removal is required, it’s the company’s responsibility to train and equip you for the job. Follow these safe work procedures:

  • ·         Clean up wet areas immediately and fix any leaks. Use ventilation to prevent moisture buildup.
  • ·         Use mould-resistant products in damp areas when possible.
  • ·         For small-scale mould removal, wear a disposable respirator such as an N95 filtering facepiece dust mask. For larger projects or when using a hazardous product as a disinfectant, a supplied-air respirator may be required (refer to the SDS for the product).
  • ·         During mould cleanup, wear disposable gloves and safety glasses.
  • ·         Wash your hands before eating, smoking, or drinking.
  • ·         Restrict access to mould-contaminated areas.
  • ·         Vacuuming may increase the spread of mould spores into the air. Use a central vacuum with outside exhaust or one equipped with a HEPA filter. Only use power tools equipped with a HEPA filter

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