Many American Households have some form of bleach as an all-purpose cleaner and surface disinfectant. Its chlorine component has a long-standing reputation for killing microbes on hard surfaces. Yet recently the Occupational Health and Safety Administration (OSHA) and other organizations like the Environmental Protection Agency are making a closer examination of bleach. This includes changing their recommendation to exclude bleach as an effective mold killing measure.

To better understand their reasoning for the change, we need to take a closer look at what mold actually is and how it spreads. Taxonomically, mold is a type of fungus, making it more than a plant, yet less than an animal. The Centers for Disease Control and Prevention note that the number of fungi species in the world is anywhere between 10,000 and as much as 300,000.

One of the things that prevent mold from being classified as a plant is its extraordinary ability to derive energy without the use of the sun. Yet it can’t be classified as an animal, because it has no means to actively pursue its food. These two interesting characteristics mean that mold is an opportunistic organism.

Of course, all living things need to have an effective mechanism of reproduction. For mold, this means sending microscopic spores into the air in hopes that they will find a suitable environment. The primary factors needed for mold spores to survive are water, warmth, and a suitable food source.

In ideal conditions, mold can take hold and start to reproduce in as little as 24-hours. This incredible rate of reproduction is what makes mold such a concern after flood damage, a ruptured pipe, or another major water incident.

Can Chlorine Bleach Kill Mold?

At first glance, bleach does appear to kill mold in the short-term. Yet many homeowners who turn to this popular surface disinfectant find mold eventually returns to the treated area. A brief look at the product label on a jug of bleach sheds further light on this problem where it will likely note that it is only effective on hard, nonporous surfaces.

This keys in on bleach’s inability to soak into porous surfaces. As a fungus mold shares some traits with plants, including a root structure known as mycelia. This means that to effectively remediate mold, the roots of the fungal infestation needs to be killed. Bleach only kills the surface cellular structures of the mold and turning the surface white. The microscopic roots remain to allow the mold to eventually grow back.

At the same time, it’s also worth noting that nearly 90% of bleach is simply water. The chloride component evaporates quickly when exposed to air, leaving behind water, which is one of the key factors mold needs to propagate.

Other Factors Counter-Indicating Bleach For Mold Remediation

The ineffectiveness of bleach to affect porous substances is just one of many factors counter indicating it for effective mold remediation. Some other facts to consider:

Under certain circumstances bleach may promote the development of more dangerous toxic mold.

The microfibers of wood and its binding lignin are weakened by chlorine bleach. Excessive use can damage the wood, compromising its structural integrity and potentially creating an even more porous surface for mold’s roots to make their home.

The chlorine component of bleach is also volatile. When it comes in contact with ammonia, such as urine it produces a small amount of toxic gas. In larger volumes, this could potentially damage delicate lung tissues.

The chlorine gas created by bleach is also known to be toxic on its own. It also releases Dioxins, which are known to be a cancer-causing agent.

When bleach comes in contact with unprotected skin it can cause skin irritation from a hydrolysis reaction. This is what causes your skin to feel slippery when exposed to bleach, as the upper layers of your epidermis start to dissolve.

What Is A More Effective Method For Safely Killing Mold?

It’s also important to keep in mind that mold spores, whether they are alive, dead, or potentially dormant still tend to act like an allergen. A hard or nonporous surface that isn’t vulnerable to water damage may be salvaged from a mold-infested environment related to water damage.

More porous substances including wood may continue to harbor a mold spore presence for a long time to come after the initial incident. To effectively kill mold in a situation like this you need a heavy duty, non-toxic, oxygen-based bleaching detergent.

Look for one that has been specially formulated to permeate porous substances where mold’s microscopic roots can linger. Since it doesn’t have any chlorine, it doesn’t produce the same toxic gas and has a far lesser threat of causing damage to your skin.

It’s also important to take measures to protect yourself against fugitive mold spores during the cleaning process. Mold spores can potentially be very toxic and can affect exposed mucous membranes including your nasal passages, throat, and lungs. Before entering an area that has been infested with the presence of mold, you should don proper safety gear such as gloves, a quality respiration mask, and safety goggles.

After cleaning away all mold affected surfaces, you should allow the surfaces to fully dry. If the area is potentially vulnerable to a future mold development, you should strongly consider seeking out a mold preventing agent. This can be especially important if the mold issue wasn’t associated with something like a ruptured pipe or a rare flooding incident. A bathroom with poor ventilation, an area in the basement that is prone to humidity and moisture buildup, or drywall that is exposed to a home’s wet wall are all potential areas that could harbor a new infestation of mold in a very short amount of time.

While bleach may have its place in the laundry room and for disinfecting hard surfaces, you should not think of it as a be-all-end-all cleaning agent. The fast evaporation rate of chlorine and the potentially dangerous gasses it produces simply mean it has no place trying to clean porous materials, especially those that have been infested with potentially toxic mold.