Mold Can Be Dangerous if Ignored!
Get No-Obligation Remediation Quotes Now

15 Different Types of Mold: Which are Toxic/Dangerous?

Get 4 Free Quotes From Competing Contractors

Type of Service
Project Details
Contact Info

Please Choose The Type of Service

It only takes 2 minutes to fill out the form

Type of Service
Project Details
Contact Info
step 2 of 4
Type of Service
Project Details
Contact Info
step 3 of 4
You are almost done - fill out this last step
Type of Service
Project Details
Contact Info

This information makes it easier to coordinate with pros.

Please fill this field
Please fill this field
Invalid zip code
Invalid email
Invalid phone number
Invalid address

By sumitting this form, you agree to be contacted about your project by Homeadvisor and / or other service partners using automated phone technology and / or email. We will not contact you with anything else.

Thank you!

Our specialists are currently reviewing your case and will get back to you shortly.

Mold is very common. That’s the unfortunate fact. It shouldn’t be this way, but it’s just the way it is. A lot of homes across the country are affected by this. There’s a good chance that it’s in your basement, bathroom, and other parts of your home.

Another unfortunate fact is that there are still some people who don’t know how it looks like. This is why we’ve put together this comprehensive article that will tackle everything there is to know about this common household issue. We’ll even tell you how it looks like.

It’s also important that you know what their health effects are. Spoiler alert: nothing good. It causes a lot of health issues particularly to one’s respiratory system.

On this page:

There are different types of mold which can be surprising to a lot of people. We’ll talk about the different types that you can find in your home. More importantly, we’ll tell you which ones are toxic and dangerous.

Of course, you want to solve this problem that you’re having. This is why we recommend that you get professional help. Yes, this is not a DIY project. If you’re concerned about the cost, we’ll tell you about a free service that can help you find a great deal to take advantage of.

What is Mold?

This is a fungus. It has small organisms that when working together, it plays an important task in nature wherein it breaks down and recycles organic matter like dead plants, leaves and trees.

It’s a different story when it’s inside a home. Yes, it can grow, survive and thrive inside a home. If there’s moisture in your home, it’s a perfect environment for it. It releases spores that can be harmful if inhaled in large amounts. Imagine living in a home where spores are airborne. Sooner or later, you’ve had inhaled a large amount of it.

How Does Mold Grow Indoors?

molded wood

Generally speaking, it just needs three things to grow, survive and thrive. It needs a food source, the right temperature and moisture. Its favorite food source is the nutrients that are present on the wood’s surface and our homes have a lot of wooden surfaces. It can grow in an environment with a temperature of at least 70 degrees Fahrenheit and most homes match this requirement.

So in reality, our home already has 2 out of 3 of these requirements. This means it only needs one thing to grow – moisture.

There are spores present in the air. They will land on surfaces. Nothing happens if that surface is dry. But if there’s moisture (plus the 2 other aforementioned requirements), it’s now the perfect environment for it to grow.

Why is there moisture in our home? It can be because of any of the following:

  • There’s been a flood.
  • There’s condensation.
  • You don’t properly dry the surfaces.
  • There’s a leak somewhere.
  • There’s a wealth of food sources like cellulose, dust, cardboard, fabric, and the likes.

What does Mold Look Like?

It’s an eyesore to look at, for starters. It looks unpleasant. This is why it’s been known to lower a home’s resale value.

You can’t actually see it if it’s just starting to grow. It’s microscopic. But it will grow if you don’t do something about it. At this point it will become visible. It’s now a colony.

This is why prevention is better than cure. Once you see it, your health would have been affected already.

It comes in different colors but the most common ones are green, blue and the dreaded black. The color is determined by a few things like how long it has been growing, what type it is, where it gets its nutrients, etc.

It can be confusing to identify mold. This is because it can be a simple stain or discoloration. This is why it’s best to contact a professional to properly identify it so that proper measures can be put in place.

Health Effects of Mold

There are different health effects of mold that can be categorized into 3:

  • Allergenic

This type targets people who are already asthmatic or allergic. In the unfortunate scenario wherein you’re allergic to it, exposure would trigger a hypersensitive response. The respiratory system will be targeted.

You’re in luck if you’re not allergic to it. It’s actually a common allergy, with up to 30% of people vulnerable to it.

  • Pathogenic

This type is more serious than the allergenic one. This can lead to scary diseases. The children and the elderly have the most risk especially since they have a weaker immune system.

There are more or less 300 fungi that can be considered as pathogenic.

  • Toxic

Just as the name implies, this type packs in the scariest health effects. It has mycotoxins that are toxic and considered to be a poison to humans.

Its main difference with allergenic and pathogenic types is the toxic type’s mycotoxins that have a mission of wreaking havoc to your health. The unfortunate thing is they can be absorbed by the body in many ways. They can be inhaled, ingested or absorbed by the skin.

Did you know that some mycotoxins are so toxic that they can be used as a weapon for biochemical warfare? Let that sink in.

The most common negative effect is an allergic reaction. This is among people who are already allergic to it or asthmatic. It’s been estimated by the American College of Occupational and Environmental Medicine that 1 out of 100 Americans is allergic to mold, so quite your unfortunate luck if you’re allergic.

Here are the other health effects to watch out for:

  • Asthma
  • Runny nose and nasal congestion
  • Difficulty of breathing
  • Tightness of the chest
  • Coughing
  • Sneezing
  • Irritation (eyes, nose, throat and skin)
  • Skin infection
  • Lung infection
  • Lung bleeding

There are other less common health effects but the list above should be enough to scare you especially if you have kids and elderly at home.

Different Types of Mold You can Find in your Home

There are more than 100,000 species out there. Not all of them are harmful and not all of them can be found in your home.

Let’s classify them into whether they’re dangerous or not for you to better understand the severity of the situation. Here are the dangerous ones:


What does it look like? It’s often in powder form when it’s reached its final form. You can identify it more by looking at its color. It’s commonly white or gray. Although sometimes, it can be orange or pink.

The thing with Acremonium is it’s usually full-blown already once you see it. This is because it grows and thrives in hidden systems in your home like in your humidifier or drain pans. It also thrives alongside Stachybotrys (more on this later), making it double trouble.

Speaking of trouble, Acremonium is considered to be dangerous and toxic. It can weaken your immune system. It can also affect your brain and bone marrow.


It grows on fabrics like wallpaper and carpets. It’s known to move fast. It’s white in color but sometimes it’s red or pink.

Some people tend to underestimate it as an allergenic. After all, its most common health effects include symptoms of an allergic reaction. However, this doesn’t mean that you can simply disregard it as an allergenic. It can be deadly if you don’t do something about it. It can infect your bones and even create an abscess in your brain.


More popularly (notoriously?) known as black mold, you just know that it’s up to no good. It’s black and looks slimy, although it can also be dark green in color. It grows on wood that has been wet for a few weeks. This is why it’s recommended that you treat water damage immediately.

Its notoriety is not uncalled for. While it also leads to minor health issues like sinusitis, it can also lead to difficulty breathing. It’s also very risky for babies and children since it can affect their neurological and pulmonary systems.

It can even cause depression, believe it or now.


It’s also black in color. Just like Stachybotrys, it grows on areas suffering from extreme and long-term water damage. It can only grow in the kitchen, basement, bathroom and areas that have a high level of condensation.

It can lead to a skin infection. It will also lead to you suffering from asthma-like symptoms. You will also have difficulty breathing. Worst case scenario is hay fever.

Here are the non-dangerous ones:

Note: While generally classified as non-dangerous, they can still cause serious health issues to those already suffering from respiratory issues, allergies or a compromised immune system:


It has a smooth and silky texture. It’s somewhat feathery with small hairs that are brown or dark green in color. It hides and grows in areas that have water damage. You can also find it under the sink or in the shower.

Being an allergenic, you can exhibit allergic reactions with prolonged exposure.


There are close to 200 species of this type so it comes in a wide variety of colors. It’s characterized by spores that are long and come together to cover a big and thick area.

It leads to an allergic reation just like Alternaria. Its main difference is it can be dangerous since it can inflame your lungs. Some species also release aflatoxins which can cause cancer.


It’s color brown if it’s been left to grow for a long time. But typically, it starts off as black, brown or pink. It hides underneath the wallpaper. As an allergenic, it can lead to irritation and even infections of the skin, nail and eyes. This makes it one of the more dangerous among the allergenics.


It starts off as white in color. It’s cottony and almost fluffy. Leave it alone and it will eventually darken until it becomes black.

You’ll usually smell it before you find it. It usually hits you with a musty smell as soon as you enter the basement or attic where it usually thrives.

It will infect your nail and skin.


It’s almost like suede to the touch. It’s usually brown or olive green in color. You can find it hiding in fabrics like carpets. It can also grow in your wooden floor.

It affects the respiratory system. This is why you’ll usually find yourself having difficulty breathing.


This gray or white type grows in dense clumps and it does so quickly. It grows in HVAC systems and in damp areas of air conditioning units.

It can lead to asthma. Exposure to it can also lead to the manifestation of flu-like symptoms. Touching it can also lead to a condition called mucormycosis which can infect your eyes and nose. Worse cases can infect your brain and lungs.


It’s dark olive in color when it matures. It starts off as whitish, grayish or brownish in color. It naturally grows on soil and grass outdoors. Water damage inside a home can lead to it growing inside your home, leading to asthmatic reactions.


It’s smooth to the touch, not that we recommend that you touch it. It’s either green or blue in color. It’s fast-spreading across water-damaged areas although it favors carpets, mattresses and ducts.

It will lead to respiratory issues which is a problem considering how effective it is at moving about while airborne.


It’s either green or white and feels like wool to the touch. It can grow virtually anywhere moisture or condensation is present.

It can lead to an allergic reaction. Most sufferers complain of sinusitis due to exposure.

Mold Color Guide

As you can see, mold comes in different colors. Knowing these colors and what they most likely signify can really help so here they are:

  • Green

Watch out if you see this color. Species that are green in color are known to release mycotoxins. Consider it dangerous to your health if you see this color.

It also comes in a few variations. Some look olive green or even greenish black.

  • White

The lack of pigmentation leads to this color. This makes them hard to spot sometimes as white blends well with the home’s interior.

  • Orange

It also affects food. While not toxic, it can slowly eat away at your home’s structure. It can also trigger an allergic reaction.

  • Yellow

It’s characterized by its slimy appearance, giving yellow mold the name slime mold.

  • Brown

This type can also look like the tan color. They grow in patches.

  • Black

Ah, the dreaded black mold. Majority of this type of mold is considered to be dangerous.

Some homeowners report pink mold. It’s not really mold, but bacteria.

DIY Mold Removal

mold being removed

As a general rule, it’s recommended that you hire a professional. DIY mold removal is not recommended but can be done provided that:

  • It doesn’t cover a big area yet. The Environmental Protection Agency states that anything bigger than 3 by 3 feet is already considered a big area.
  • It’s on an area where it can be easily removed like on a carpet.
  • It’s on an area that’s easy to clean like glass or tiles.
  • You’re not allergic to mold and you’re not suffering from any condition wherein exposure will make it worse.
  • You have the training and experience.

Doing the task DIY is usually not a good idea because of the following reasons:

  • In addition to health concerns brought by mold itself, it usually carries contamination that can make it worse. This is because of its exposure with sewage, chemicals and the likes.
  • Most of the time, they’re hidden behind walls, HVAC systems, ceiling and the likes. While you can remove the ones that you can see, how about the ones that you can’t? It’s in your best interest to make sure that they’re all removed. Specialists are trained to find even the most hidden mold.
  • As mentioned above, it has negative health effects. You wouldn’t want to expose yourself to these dangers. Professionals have the tools and training to protect themselves.
  • There are other tasks related to the removal. For example, do you know how to replace the drywall after you’ve removed it? Do you know how to remove it?

How to Assess the Mold Levels

Another reason why it’s not a good idea to do it DIY is because you have to know what you’re up against. Do you know how to assess the mold levels? It requires a lot of training and specialized equipment to do so.

A trained professional will do a thorough inspection of your home first. Their heightened sense of smell should be able to pick up odors indicating mold growth. They will also check potential moisture sources like leaks. They will check every inch of your home. They will even look behind your wallpaper and in your ductwork.

Later on, they should be able to zero in on the potential problem areas. In most cases, a trained professional can make an assessment of the mold levels after a thorough inspection. At this point they should be able to create an action plan to tackle the problem.

There are cases wherein sampling is needed. Sampling should be conducted by a trained professional. This is required by the United States Environmental Protection Agency in order to determine just how concentrated the airborne spores are or if you need to identify the specific species that you’re dealing with.

Air sampling is the most common technique but it has its disadvantages. This is why it’s sometimes complemented by laboratory testing using a sample taken using a cotton swab. Dust samples can also be used.

Get the Help of Professional Mold Remediation Companies

Mold will wreak havoc on any home. If its presence alone can lead to dangerous health effects, imagine how handling it will affect you.

This is why it’s recommended that you get the help of professional mold remediation companies. These companies have trained professionals that can assess, spot and solve the problem. They can even help prevent a future reoccurrence.

Best of all, they will solve the problem by also solving the root cause. They will do it right. This makes paying for them worth it.

Get Quotes from Competing Contractors

black mold

If you’re concerned about how much you have to pay a professional, we have good news for you. We’ve put together a free service that allows you to contact mold remediation companies in your area. This free service will limit the contact to the best contractors that specialize on the task at hand.

What you need to do is to use the form that you see on this page. You just have to complete the form with the details asked. You’ll see that it’s only asking for basic details. Every detail is needed so that the contractors will have everything they need to help you out.

What happens after you send the form? The best companies that perform mold remediation will receive the details. They will use these details to put together their best quote so they can offer you their best deal.

Why would they offer you their best deal when most companies would go for maximum profit? It’s because of how this service is set up. It’s set up in such a way that these companies will be competing for your business. These companies know that other companies will be receiving your details so it’s in their best interest to send their best deal or else, they risk losing your business to a competitor. They know this and this is why you can expect to receive up to 4 of the best quotes.

This quote will be itemized so you can choose wisely. You can compare them so you’ll really find the best deal offered.

There’s no risk involved in using this service. In addition to being a free service, there’s also no commitment involved. You don’t have to hire anyone after you receive their quote. But with how this service is set up, you’ll surely find a quote that makes sense.


Get The House You Always Dreamed of

Get Ready to Have No-Obligation Talks With Contractors

Talk With a Contractor