Understanding Mold in Indoor Living Spaces
As mold concerns in homes and apartments have become more common, so have the questions and misconceptions surrounding proper treatment. As a Certified Microbial Consultant and Certified Microbial Remediation Supervisor, I have heard countless myths about how mold should be handled. With so much information online, many tenants research the issue themselves. The challenge is that not everything on the internet is accurate. With conflicting advice widely available, misinformation often spreads faster than facts.
Common Mold Myths and Misconceptions
One of the most frequent mistakes people make is spraying visible mold with chlorine bleach to “kill” it. Unfortunately, this approach can actually make the indoor environment more hazardous, especially for individuals sensitive to mold exposure.
Another common claim is that someone has “black mold” or “killer black mold.” In reality, that term is misleading. While many types of mold can be harmful when present indoors in elevated levels, most health effects are allergenic in nature. Symptoms may range from itchy skin to persistent cold-like symptoms that linger for weeks.
Those most vulnerable include very young children, the elderly, individuals recovering from surgery, and people who are immunocompromised. Although severe illness stories circulate, such outcomes are statistically rare. In most cases, once the contamination is properly removed, symptoms resolve.
Proper Mold Remediation: Removal vs. Killing
When elevated mold levels are present indoors, the correct approach is removal of mold spores, not simply killing them.
Mold spores are microscopic and cannot be seen by the naked eye. Even if a spore is dead, it can still circulate through the air carrying mycotoxins. According to Environmental Protection Agency and other authoritative sources, mycotoxins are toxic substances produced by certain molds. These toxins can remain problematic whether the spore is alive or dead.
The key point is this: dead mold spores can still pose health concerns. That is why proper removal, rather than surface treatment with bleach, is the correct remediation strategy.
Mold Spores in the Air: What You Need to Know
Mold spores exist everywhere in our environment. No home is completely free of them. These spores are extremely small. For perspective, the tip of a human hair measures about 100 microns in diameter, while a typical mold spore measures roughly 2 microns, about 50 times smaller.
When visible mold growth appears on a surface, you are seeing millions of spores clustered together. This represents elevated mold levels. Whether those spores are actively circulating in the air depends on environmental conditions.
When a mold spore lands on a surface that provides both a food source, such as cellulose materials, and adequate moisture, it begins to grow and multiply.
Mold Growth, Moisture, and Aerosolization
If the moisture source disappears, mold can enter a dormant state known as stasis. However, when mold dries out, spores can begin to aerosolize. This means they become airborne and enter the air you breathe.
This aerosolization also occurs when chlorine bleach is sprayed onto mold. While the bleach may kill the organism, it can trigger the release of spores into the air. Dead spores in the air are not necessarily safer than live ones, particularly from a health standpoint.
Why Disturbing Mold Can Increase Airborne Spores
Another often overlooked fact is that disturbing visible mold dramatically increases airborne spore levels. Simply blowing air across mold growth can send spores into the breathing zone.
Standard remediation protocols typically involve:
- Cleaning nonporous materials such as metal, tile, and stone
- Removing porous materials such as drywall and medium density fiberboard, often called particle board
During removal, airborne mold levels can increase significantly. For this reason, professional remediation is usually performed under containment conditions. This includes negative air pressure and HEPA filtration.
HEPA Filtration and Mold Control
HEPA stands for High Efficiency Particulate Arrestor. To meet U.S. government standards, a HEPA filter must remove 99.97 percent of particles that are 0.3 microns in size from the air that passes through it.
Because mold spores average around 2 microns, HEPA filtration is highly effective at capturing them. Standard vacuum filters are not designed to trap particles this small. In fact, vacuuming without HEPA filtration can re-aerosolize spores back into the air.
Similarly, many ionic and UV filtration devices marketed to consumers may offer limited benefit unless they meet HEPA standards. When addressing mold contamination, proper air filtration is essential.
Accurate Mold Information Matters
When dealing with indoor mold, accurate information is critical. Acting on myths or incomplete advice can worsen the situation rather than improve it.
The Environmental Protection Agency offers a free resource titled A Brief Guide to Mold, Moisture, and Your Home, available at epa.gov/mold. This guide provides practical, science-based recommendations for homeowners and tenants.
About Mike Cosley
Mike Cosley is a Certified Microbial Consultant who has performed thousands of mold remediations. He was called upon as an expert witness in the largest mold case in U.S. history and is recognized as a leading authority in the field. He can be contacted at www.cdforensics.com or by phone at (661) 510-6181.
