Mold Statistics and Facts

For over 15 years, Mold Busters have been conducting non-viable indoor air quality assessments for residential and commercial properties to help ascertain their current indoor fungal ecology.

Our certified inspectors have collected air samples from Southern Ontario to Eastern Ontario and all of Western Quebec as part of our mold testing services. All collected spore trap samples have been sent to an accredited, third-party laboratory that specializes in microbial analysis. We have ensured our sampling equipment has been properly calibrated, all sampling media maintained in good condition and all indoor environmental requirements for accuracy in the analytical process adhered to.

The result has been an incredible collection of mold spore concentrations, broken down by genus, as it relates to indoor and outdoor environmental conditions.

A small number of these assessments, starting from 2018, have been catalogued, dissected and compiled into the statistics you will see below. Our proprietary Mold Spore Sweeper (MSS*) has combed through hundreds of our own laboratory reports, separating each spore type and its associated count by cubic meter. Furthermore, our MSS has classified every sampled location – whether it be a basement, office, or outdoor environment – and categorized the toxicity potential for each identified spore type.

This will be a dynamic statistics page that will update regularly as the MSS continues to work its magic behind the scenes in order to bring you this incredible dataset.

  • Total of 1339 properties tested.
  • Total of 990 outdoor samples taken.
  • Toxigenic species of mold we scan for during our indoor air quality tests are: Stachybotrys, Chaetomium, Fusarium, Penicillium/ Aspergillus group and Alternaria. In our process of giving recommendations for mold removal to our client, it doesn’t matter if there is 1 spore or 1 billion spores of toxigenic species, we always give suggestions for mold remediation. Client is safe only there is no toxic mold spore found indoor.
  • Other mold types we scan for during our indoor air quality tests are: Ascopores, Basidiospores, Cladosporium, Epicoccum nigrum, Ganoderma, Hyphal Fragment, Mitospores, Pithomyces, Pollen, Smuts / Periconia / Myxomycetes. These mold types are classified as “elevated” based on the numerical value comparison to the baseline/outdoor sample. If they are higher indoors than outdoors, it’s considered elevated and recommendations can be made (range from improving ventilation, general cleaning or even remediation/disinfection).

Toxic Mold Types Found Indoors and Outdoors

Stats Toxic Mold Types Found Indoors and Outdoors

Numbers explained:

Most common toxic mold types found in homes, ordered by presence:

  1. Penicillium/Aspergillus group (38%)
  2. Chaetomium (17%)
  3. Stachybotrys (16%)
  4. Alternaria (9%)

Only 12% of tested homes didn’t have any presence of mold

Stats Presense of Mold in Homes

Most common toxic mold types found outdoors, ordered by presence:

  1. Penicillium/Aspergillus group (53%)
  2. Alternaria (17%)
  3. Chaetomium (4%)
  4. Stachybotrys (2%)

Only 6% of tested outdoor air samples didn’t have any presence of mold

Stats Presense of Mold Outdoor

Other Mold Types Found Indoors and Outdoors

Stats Other Mold Types Found Indoors and Outdoors

Numbers explained:

Most common mold types found in homes, ordered by presence:

  1. Basidiospores (27%)
  2. Cladosporium (27%)
  3. Hyphal Fragment (25%)
  4. Smuts/Periconia/Myxomycetes (19%)
  5. Mitospores (17%)
  6. Pollen (15%)
  7. Ascospores (14%)
  8. Ganoderma (9%)
  9. Epicoccum nigrum (7%)
  10. Pithomyces (7%)

Most common mold types found outdoors, ordered by presence:

  1. Basidiospores (76%)
  2. Cladosporium (67%)
  3. Ascospores (59%)
  4. Hyphal Fragment (37%)
  5. Ganoderma (32%)
  6. Pollen (28%)
  7. Smuts/Periconia/Myxomycetes (28%)
  8. Epicoccum nigrum (12%)
  9. Mitospores (10%)
  10. Pithomyces (5%)

Stats About Mold Types Found in Basements

Toxic mold types in basements:

Stats Toxic Mold Types in Basements

Most common mold types in basements:

Stats Most Common Mold Types in Basements

Percentage of basements without any mold:

Stats Percentage of Basements Without Any Mold

Numbers explained:

  • Toxic mold types found in basements (ordered by presense) are: Penicillium/Aspergillus group (71%), Chaetomium (17%), Stachybotrys (17%), Alternaria (9%).
  • Common mold types in basements (ordered by presense) are: Basidiospores (69%), Cladosporium (56%), Hyphal fragment (39%), Ascospores (28%), Smuts/Periconia/Myxomycetes (22%), Pollen (15%), Mitospores (15%), Ganoderma (14%), Pithomyces (8%) amd Epiccocum nigrum (6%).
  • Only 8% of tested basements didn’t have mold present.

Stats About Mold Types Found in Bathrooms

Toxic mold types in bathrooms:

Stats Toxic Mold Types in Bathrooms

Most common mold types in bathrooms:

Stats Most Common Mold Types in Bathrooms

Percentage of bathrooms without any mold:

Stats Percentage of Bathrooms Without Any Mold

Numbers explained:

  • Toxic mold types found in bathrooms (ordered by presense) are: Penicillium/Aspergillus group (59%), Chaetomium (17%), Stachybotrys (16%), Alternaria (10%).
  • Common mold types in bathrooms (ordered by presense) are: Basidiospores (64%), Cladosporium (57%), Hyphal fragment (36%), Ascospores (26%), Smuts/Periconia/Myxomycetes (21%), Pollen (19%), Ganoderma (13%), Mitospores (11%), Epiccocum nigrum (7%) and Pithomyces (4%).
  • Only 13% of tested bathrooms didn’t have mold present.

Stats About Mold Types Found in Bedrooms

Toxic mold types in bedrooms:

Stats Toxic Mold Types in Bedrooms

Most common mold types in bedrooms:

Stats Most Common Mold Types in Bedrooms

Percentage of bedrooms without any mold:

Stats Percentage of Bathrooms Without Any Mold

Numbers explained:

  • Toxic mold types found in bedrooms (ordered by presense) are: Penicillium/Aspergillus group (62%), Chaetomium (11%), Stachybotrys (10%), Alternaria (7%).
  • Common mold types in bedrooms (ordered by presense) are: Basidiospores (60%), Cladosporium (48%), Hyphal fragment (31%), Ascospores (32%), Smuts/Periconia/Myxomycetes (20%), Pollen (17%), Mitospores (12%), Ganoderma (11%), Epiccocum nigrum (5%) and Pithomyces (3%).
  • Only 11% of tested bedrooms didn’t have mold present.

Stats About Mold Types Found in Kitchens

Toxic mold types in kitchens:

Stats Toxic Mold Types in Kitchens

Most common mold types in kitchens:

Stats Most Common Mold Types in Kitchens

Percentage of kitchens without any mold:

Stats Percentage of Kitchens Without Any Mold

Numbers explained:

  • Toxic mold types found in kitchens (ordered by presence) are: Penicillium/Aspergillus group (57%), Chaetomium (14%), Stachybotrys (9%), Alternaria (8%).
  • Common mold types in kitchens (ordered by presense) are: Basidiospores (65%), Cladosporium (37%), Ascospores (28%), Hyphal fragment (26%), Smuts/Periconia/Myxomycetes (16%), Pollen (9%), Mitospores (9%), Ganoderma (12%), Epiccocum nigrum (6%) and Pithomyces (2%).
  • Only 8% of tested kitchens didn’t have mold present.

Stats About Mold Types Found in Living Rooms

Toxic mold types in living rooms:

Stats Toxic Mold Types in Living Rooms

Most common mold types in living rooms:

Stats Most Common Mold Types in Living Rooms

Percentage of living rooms without any mold:

Stats Percentage of Living Rooms Without Any Mold

Numbers explained:

  • Toxic mold types found in living rooms (ordered by presence) are: Penicillium/Aspergillus group (68%), Chaetomium (14%), Stachybotrys (9%), Alternaria (9%).
  • Common mold types in living rooms (ordered by presense) are: Basidiospores (71%), Cladosporium (56%), Hyphal fragment (37%), Ascospores (33%), Smuts/Periconia/Myxomycetes (26%), Pollen (18%), Mitospores (13%), Ganoderma (13%), Epiccocum nigrum (7%) and Pithomyces (7%).
  • Only 8% of tested living rooms didn’t have mold present.

Stats About Mold Types Found in Storage Rooms

Toxic mold types in storage rooms:

Stats Toxic Mold Types in Storage Rooms

Most common mold types in storage rooms:

Stats Most Common Mold Types in Storage Rooms

Percentage of storage rooms without any mold:

Stats Percentage of Storage Rooms Without Any Mold

Numbers explained:

  • Toxic mold types found in storage rooms (ordered by presense) are: Penicillium/Aspergillus group (66%), Stachybotrys (17%), Alternaria (12%), Chaetomium (11%).
  • Common mold types in storage rooms (ordered by presense) are: Basidiospores (63%), Cladosporium (46%), Hyphal fragment (37%), Ascospores (27%), Smuts/Periconia/Myxomycetes (15%), Pollen (14%), Mitospores (10%), Ganoderma (9%), Pithomyces (7%) and Epiccocum nigrum (6%).
  • Only 11% of tested storage rooms didn’t have mold present.

Stats About Mold Types Found in Office Rooms

Toxic mold types in office rooms:

Stats Toxic Mold Types in Office Rooms

Most common mold types in office rooms:

Stats Most Common Mold Types in Office Rooms

Percentage of office rooms without any mold:

Stats Percentage of Office Rooms Without Any Mold

Numbers explained:

  • Toxic mold types found in office rooms (ordered by presence) are: Penicillium/Aspergillus group (53%), Stachybotrys (14%), Chaetomium (10%), Alternaria (8%).
  • Common mold types in office rooms (ordered by presense) are: Basidiospores (64%), Cladosporium (53%), Hyphal fragment (34%), Ascospores (26%), Smuts/Periconia/Myxomycetes (21%), Pollen (19%), Mitospores (18%), Ganoderma (12%), Pithomyces (6%) and Epiccocum nigrum (5%).
  • Only 20% of tested storage rooms didn’t have mold present.

Toxic Mold Types Compared in Ontario and Quebec

Stats Toxic Mold Types Compared in Ontario and Quebec

Numbers explained:

Most common toxic mold types found in Ontario, ordered by presence:

  1. Penicillium/Aspergillus group (38%)
  2. Chaetomium (16%)
  3. Stachybotrys (17%)
  4. Alternaria (9%)

Only 12% of tested homes in Ontario didn’t have any presence of mold

Stats Presense of Mold Outdoor

Most common toxic mold types found in Quebec, ordered by presence:

  1. Penicillium/Aspergillus group (37%)
  2. Chaetomium (18%)
  3. Stachybotrys (15%)
  4. Alternaria (9%)

Only 13% of tested homes in Quebec didn’t have any presence of mold

Stats Presense of Mold in Homes

Other Mold Types Found in Ontario and Quebec

Stats Other Mold Types Found Indoors and Outdoors

Numbers explained:

Most common mold types found in Ontario, ordered by presence:

  1. Cladosporium (29%)
  2. Basidiospores (26%)
  3. Hyphal Fragment (23%)
  4. Smuts/Periconia/Myxomycetes (20%)
  5. Mitospores (19%)
  6. Pollen (16%)
  7. Ascospores (14%)
  8. Ganoderma (9%)
  9. Epicoccum nigrum (8%)
  10. Pithomyces (7%)

Most common mold types found in Quebec, ordered by presence:

  1. Basidiospores (28%)
  2. Hyphal Fragment (27%)
  3. Cladosporium (24%)
  4. Smuts/Periconia/Myxomycetes (20%)
  5. Mitospores (17%)
  6. Ascospores (13%)
  7. Pollen (13%)
  8. Ganoderma (9%)
  9. Pithomyces (8%)
  10. Epicoccum nigrum (6%)

Mold Facts

96% of chronic sinus infection is caused by mold

(Mayo Clinic Study, 1999)

Chart Chronic Sinus Infections Caused by Mold

25% of the Population is Susceptible to Mold Illness

(Mold Sensitized, 2015)

Chart 25% of Population is Susceptible to Mold Illness

Fact Deaths Lined to Air Pollution
Fact Unhealthy Levels of Mold
Fact 24-48 hours to Mold Growth
Fact Mold Exposure in Homes

About 40% of asthma episodes are triggered by the household presences of mold, dust mites, or rats

(Center For American Progress, 2016)

Chart Asthma Episodes Triggered by Mold