The key to mould prevention is to remove excessive moisture build-up and control relative humidity through proper home maintenance and by following these steps:
- Use an exhaust fan when you shower or bathe. An exhaust fan should be installed in each bathroom.
- Check and maintain exhaust fans to make sure there is adequate air movement and that they are vented to the outside and not into the attic.
- Keep the exhaust fan running for at least 30 minutes after a shower or bath.
- Keep surfaces clean and dry. Squeegee and dry the walls around the bathtub and shower after use.
- Repair or replace open, cracked or damaged tiles, grout and caulking around showers and tubs.
- Repair plumbing leaks promptly.
- Remove any visible mould by scrubbing with unscented dishwashing detergent and water.
- Always use a kitchen range hood exhaust fan when cooking, preferably on the highest setting.
- Consider using the back burners only.
- Maintain the exhaust fan to make sure there is adequate air movement and that it vents to the outside.
- Washing machine
- Leave the washing machine door open when not in use so that any remaining water can dry. This will help reduce mould and bacteria growth inside the washing machine.
- Make sure that the washing machine drains directly into the laundry sink/drain without dripping or splashing outside of the basin. Use pipe extensions to reduce any splashing.
- Regularly check hoses and connections for leaks.
- Be aware that hanging wet laundry indoors can increase indoor relative humidity levels.
- Clothes dryer
- Check that your clothes dryer vents to the outside.
- Seal the joints in the dryer duct with foil tape.
- Clean the lint tray every time you use the dryer.
- Routinely inspect the outside exhaust vent and remove any built-up lint.
- Make sure the outside vent is kept clear of obstructions, such as snow and foliage.
Condensation on windows, window frames and sills
- Promptly repair any leaks.
- Maintain your home's relative humidity level between 30% and 50%.
- Use exhaust bathroom fans and a kitchen range hood.
- Keep window coverings open to allow warm air to reach the windows. Heavy curtains or blinds can trap the cold and moisture and cause condensation on your windows.
- Keep baseboards or heating vents clear of furniture and leave interior doors open to facilitate airflow.
- Dry your window frames and sills daily to keep water from dripping and causing mould to grow.
- Unplug and remove humidifiers.
- Run a dehumidifier in your basement to help reduce dampness year-round, if necessary. Make sure the windows are closed when the dehumidifier is running.
- Check plumbing pipes for condensation. Dry pipes and insulate them with foam insulation.
- Keep areas and storage spaces free of clutter, especially if near an outside wall.
- If you use the basement for storing items, use plastic bins with lids instead of cardboard.
- Never place cardboard boxes directly on the basement floor.
- Consider removing any carpets from the basement floor.
- Ensure prompt and complete cleanup after a flooding event.
- Store firewood in the garage or shed, not inside the house.
- Have family and friends take off their shoes at the door before entering your home.
- Keep beds, bedding and furniture away from outside walls for good airflow.
- Keep closets and storage spaces free of clutter, especially if near an outside wall.
- Vacuum often. Use a vacuum with a high efficiency particulate air (HEPA) filter, or a central vacuum vented outdoors.
- Clean hard floors with a damp mop.
- Never use bleach to clean up mould.
Note: If renting a house or an apartment unit speak to the property owner about any moisture or mould problems. Information on landlord/tenant issues, rights and responsibilities is available from your provincial/territorial government.
For more information, please visit Health Canada's indoor air quality webpage or contact us at firstname.lastname@example.org.
- Footnote 1
Health Canada. (2007). Residential Indoor Air Quality Guidelines: Mould. Government of Canada, Ottawa, Canada.
Return to footnote 1 referrer
- Footnote 2
Hung LL, Caulfield SM, Miller JD. (2020). Recognition, Evaluation, and Control of Indoor Mold, 2nd edition (AIHA Green Book). American Industrial Hygiene Association, Falls Church VA, USA.
Return to footnote 2 referrer
- Footnote 3
Chew GL, Horner WE, Kennedy K, Grimes C, Barnes CS, Phipatanakul W, Larenas-Linnemann D, Miller JD. (2016).; Environmental Allergens Workgroup. Procedures to assist health care providers to determine when home assessments for potential mold exposure are warranted. J Allergy Clin Immunol Pract. 4(3):417-422.e2.
Return to footnote 3 referrer
- Footnote 4
Berry P., & Schnitter, R. (Eds.). (2022). Health of Canadians in a Changing Climate: Advancing our Knowledge for Action. (https://changingclimate.ca/site/assets/uploads/sites/5/2022/02/CCHA-REPORT-EN.pdf). Ottawa, ON: Government of Canada.
Return to footnote 4 referrer
- Footnote 5
Eykelbosh A., Steiner L. (2018). National Collaborating Centre for Environmental Health. Growing at Home: Health and Safety Concerns for Personal Cannabis Cultivation. (https://ncceh.ca/documents/evidence-review/growing-home-health-and-safety-concerns-personal-cannabis-cultivation).
Return to footnote 5 referrer
- Footnote 6
Palaty C, Shum M. (2010, rev. 2014). National Collaborating Centre for Environmental Health. Mould Assessment Recommendations. (https://ncceh.ca/sites/default/files/Mould_Assessment_Evidence_Review_March_2014.pdf).
Return to footnote 6 referrer
- Footnote 7
New York City Department of Health and Mental Hygiene (NYCDHMH). (2008).
Guidelines on Assessment and Remediation of Fungi in Indoor Environments (https://www1.nyc.gov/assets/doh/downloads/pdf/epi/epi-mold-guidelines.pdf). 25 p.
Return to footnote 7 referrer
- Footnote 8
National Institute for Occupational Safety and Health (NIOSH). (2018). Dampness and Mold Assessment Tool for General Buildings - Form & Instructions. (https://www.cdc.gov/niosh/docs/2019-115/pdfs/2019-115.pdf). Cox-Ganser J, Martin M, Park JH, Game S. Morgantown WV: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2019-115.
Return to footnote 8 referrer
- Footnote 9
Health Canada. (2021). Infographic: Flood clean up and indoor air quality. (https://www.canada.ca/en/health-canada/services/publications/healthy-living/infographic-flood-clean-up-indoor-air-quality.html).
Return to footnote 9 referrer
- Footnote 10
Institute of Inspection Cleaning and Restoration Certification (IICRC). (2015). ANSI/IICRC S520 Standard and IICRC R520 Reference Guide for Professional Mold Remediation.
Return to footnote 10 referrer
- Footnote 11
Mendell MJ, Adams RI. (2022). Does evidence support measuring spore counts to identify dampness or mold in buildings? A literature review. J Expo Sci Environ Epidemiol. 32(2):177-187.
Return to footnote 11 referrer