What are the Different Colors of Mold?

petri dish containing many different colors of mold

Colorful is not something one would typically associate with things that are considered unpleasant, but molds buck that trend. They come in an astonishing variety of colors: They’re Black, Blue, Green, Orange, Gray, Yellow, White, Pink and Brown. I’m sure there are possibly more, but that’s all my research found!

Whatever the color, there is no doubt about one thing: If it’s in your home, you need to get rid of that mold as quickly as possible.

If you suffer from any of the symptoms of mold exposure but can’t find a source, it could well be hidden out of sight. Under the bath tub, behind cupboards or tiling are the usual areas to check but that list is non-exhaustive. Remember, mold does not require light to grow.

It is true that in the grand scheme of things, molds play an important role in our planet’s ecological cycle, but here on Freshairguide, we’re more concerned with the bad stuff growing in your home that can cause a host of health problems from skin rashes and headaches to respiratory disorders and cancer.

What kind of mold is dangerous?

Typically when people talk about dangerous toxic mold that’s bad for our health, they’re talking about any mold that contains mycotoxins.These are a by-product of certain types of mold and fungus. These particles attach themselves to the spores of the mold, which are so tiny, it’s easy for them to become airborne. At which point, if you’re in the vicinity of the mold growth – chances are you just inhaled them.

The risks associated with exposure to these deadly mycotoxins are vastly underrated by many of us. Toxic mold exposure can elicit a wide range of negative responses, especially for the very young and old, and anyone with a weakened immune system or those that suffer from allergies and asthma.  Autopsies and studies show that exposure to indoor toxic mold may well be to blame for far more deaths in the United States than we might give it credit for.

Not all molds are toxic thankfully. In fact, the large majority are not harmful to humans in any way – even those with weakened immune systems. They do however come in a range of wonderful colors and I think it’s a good idea to be able to identify different types that might be growing in your home, so you can deal with them more effectively.

If you suspect you are at high risk of mold growth in your home, along with cleaning down any surfaces that have been contaminated, I highly advise you buy an air purifier for mold. We have a great review guide on mold purifiers that looks at some of the best models for the job.

So what accounts for this diversity of colors and what do these colors indicate?

Scientists still don’t have a clear idea of why molds have different colors, but research by fungal biologist Nicholas Money at Ohio’s Miami University indicates that colorless molds are less harmful than molds with color. It’s also worth remembering that the same mold type can appear in several different colors which can make it very difficult to identify any particular type of mold by appearance alone. It can however provide you with a good starting point in your research, so let’s cut to the chase and look at the various colors of molds you should be aware of:

Green mold

wall covered in green mold

Several varieties of mold can appear green, including: Penicillium, Cladosporium and Aspergillus

Green is the most generic color of fungi, and provides little information by itself on the type of mold. There are literally thousands of varieties of green mold, and you would have to probe deeper to pin-point the exact nature of the green mold. But it’s clear it’s not fun to have this stuff lurking on your bathroom walls or under the kitchen sink.

Aspergillus, Penicillium and Cladosporium are among the most common forms of green mold. Aspergillus is the icky stuff formed on stale bread and other foods, among other non food related surfaces.

White mold

White mold on breeze blocks

Sclerotinia sclerotiorum or white mold

White mold, also known as Chaetomium can be found deposited almost anywhere and adjusts itself to most host materials especially in damp and dark conditions. This mold looks a bit like cotton and is one of the more musty smelling of all molds. The basement and attic are particularly vulnerable, but so are foods. White mold tends to resemble salt deposits left behind on walls.

Pink mold

Pink mold growing on wood

Serratia marcescens or pink mold

You might have noticed a pinkish film developing on your shower curtain or bath tub if it has not been washed for a while. This is typically “pink mold”, Serratia marcescens in scientific parlance. There is no permanent solution for this except to clean the bathroom regularly. Strictly speaking, pink mold is a form of bacteria and the more scientifically minded would not classify it as mold.

Yellow mold

yellow slime mold growing on a wall

Also referred to as slime mold. A member of the Myxomycetes family

Is yellow mold dangerous? well..it depends.  Some yellow mold, like the ‘yellow slime mold’ pictured above can be highly toxic and should be removed immediately. Don’t make the mistake of touching it or inhaling it as it can lead to several health problems. Other types of yellow mold come in less dramatic shades of yellow. Aspergillus, for instance, can also appear as yellow. Serpula lacrymans, is another yellow colored mold which is commonly found growing on indoor or outdoor wooden surfaces. This mold has evolved into a very adept destroyer of damp and rotting wood.

So, which type of yellow mold should be avoided? – If you spot yellow mold that is a very bright variant of the color (and so easily detected) chances are this is the highly toxic variety. If you want to make sure, I suggest you buy a mold test kit to help identify it.

Grey or black mold

A wall covered in Alternaria - grey / black mold

Alternaria: a grey black color mold

There’s a good chance that this is Alternaria (pictured above), typically an outdoor mold found in dusty, damp spaces and near plants and soil. Lately, it is also increasingly being found in homes and the dust in your home can have traces of it. Exposure to Alternaria has been linked to increased risk of asthma.

Toxic black or greenish-black mold

black mold growing on a wall

tachybotrys chartarum (black mold) the deadliest of all molds

If molds were a gangster film, the infamous ‘toxic’ black mold would be the Godfather. Going by the scientific name of Stachbotrys chartarum, the black or greenish-black mold is the main culprit for releasing those mycotoxins we talked about earlier. This stuff is no joke. Exposure to certain mycotoxins is seriously dangerous to human health . Some warning signs associated with toxic black molds are persistent coughing and sneezing, rashes, periodic headaches, and fatigue.

For people with pre-existing conditions like asthma or allergies, black mold poisoning can even be fatal.

This mold is typically found in leaky areas, old decaying wood, paper and foods. Stachybotrys chartarum releases it’s spores while feeding on organic materials that are rich in moisture.

Brown mold

wall covered in brown mold

brown mold comes in many different forms

Certain types of brown mold can spread rapidly after appearing on hard surfaces. There are many different types of mold that can appear brown in color. These include (but not limited to) Pithomyces chartarum, Aureobasidium pullulans, Stemonitis and Taeoniella. In order to determine the exact type, you would have to get it checked in a lab. Remember, the same mold types can also appear in other colors.

Brown molds tend to develop a darker hue because of the surface they’re growing on. The mold may also have a particularly musty odor.

Though not dangerous like ‘toxic’ black mold, brown mold does still release spores which can cause coughing, sneezing and other allergic reactions.

Orange mold

wall covered in Orange mold

penicillium vanoranje is the scientific name of this strain of orange mold

This awesome looking mold is commonly found outdoors but can settle on wooden structures inside homes and surfaces like beams and floors. It can cause damage to the structure in the long term. While prolonged exposure can aggravate pre-existing conditions like asthma, orange molds generally don’t pose a major health risk.

This article was written by Fin Tatello – check out his author bio here