How Big Are Mold Spores -Mold Spore Size & Identification

Are you concerned about mold spores in your home? Or keen to know how you can filter mold spores out of your home? 

In This Guide You Will Learn: 

  • How to identify different types of mold and the size of their Spores
  • Where you can find mold spores in the home, 
  • How you can filter mold spores out of your home & How it depends on the mold spore sizes.

Can You See Mold Spores? 

Unlike mold itself, mold spores are not visible to the naked eye. If they were, we’d perhaps feel quite unsettled as mold spores are present in all indoor environments – even where mold cannot grow. 

Mold spores can enter the home in a variety of ways, most often in the air via windows, ventilations systems and open doors. However, they also travel through us! Whether that’s on our clothes, shoes, objects or even our pets.  

Mold Spore Sizes in Microns  

Mold spores are measured in microns and 1 micron is a millionth of a meter. The average mold spore can range from 10 – 30 microns in size which for context is larger than the average household dust and smaller than a grain of beach sand.  

To give you a visual idea for comparison, the eye of a needle sizes in at 1,230 microns. So, mold spores are incredibly small however the size is dependent on the type of mold. For example, black mold spores can range up to 100 microns which is considerably larger than the average mold spore.  

What do Mold Spores Look Like?  

Mold spores are not visible without a microscope therefore being able to identify different types of mold could be the difference between suffering a mild allergy or an inflammatory response. Here is a list and description of some of the most common types of mold. 

Common Types of Mold 

  • Stachybotrys is known as black mold and is a toxic species often found inside houses. It’s characterized by a fuzzy consistency and predominantly black in color with shades of green. Its spores are released in clumps.  
  • Memnoniella is also alluded to as black mold and has the same effects as stachybotrys although its spores are released in chains rather than clumps.  
  • Aspergillus is a more common mold that appears on wooden surfaces. It often causes allergies that can lead to serious reactions or infections. It can be identified by its gray or green flecks. 
  • Alternaria often grows in damp areas such as under the sink. It is black in color with a fuzzy, velvety texture.  
  • Penicillium is often green or blue in color and manifests in circles with a deeper color in the middle. It is most commonly found on decaying fabric and wallpaper.  
  • Cladosporium like penicillium can cause mild allergies such as hay-fever or asthmatic symptoms. It has an olive-green or brown pigmentation and is typically found outdoor on porous surfaces however can be carried indoors.  
  • Bipolaris is typically found outdoors in moist environments and therefore can grow in water damaged materials indoors such as carpets. It is white and brown in color before turning dark olive as it matures. When its spores are inhaled, you may suffer from common allergic symptoms such as a stuffy nose.  
  • Ulocladium is a common mold that thrives in soil and wetness so is only usually found in buildings when they’ve experienced severe water damage. It’s darkly pigmented and often grows in conjunction with other species of mold.

Are Mold Spores Smaller than Pollen? 

Pollen grains are on average between 10 – 1000 microns in size whereas mold spores are between 10 – 30 making the average mold spore considerably smaller than a grain of pollen.  

This helps us to understand why pollen often causes us to sneeze as the particles get caught in the nasal pathway whereas mold spores are far more easily breathable. Mold spores are also small enough to be ingested whereas pollen is not.   

How Long do Mold Spores Stay in the Air? 

Mold spores will remain in the air indefinitely until nearby mold is removed and even then, it is possible that some mold spores will remain as they can enter the space from elsewhere. Using an air purifier is a great way to filter out airborne spores once any nearby mold has been removed. 

As well as using an air purifier, it is important to vacuum often as well as changing and washing bedding frequently to prevent excess mold spores collecting. Removing trash cans regularly is also imperative to prevent the mold spore count increasing drastically.

Mold Spore Size vs Virus 

A virus can range anywhere from .005 – 0.3 microns which is considerably smaller than the average mold spore. This is why in a hospital; HEPA filters are used as they can remove 99.97% of particles with a diameter of 0.3 microns. 

Although mold spores are larger than virus particles, mold spores are still capable of evading filters as they can collect and stick to surfaces. Cleaning consistently, especially in damp environments such as the restroom or kitchen is therefore still important when you have a functional HEPA filter.

Will a HEPA filter remove mold spores? 

The short answer is yes. The best HEPA (high-efficiency particulate absorbing) filters satisfy hospital standards of filtering and can remove airborne virus particles that are significantly smaller than mold spores with a 99.97% efficiency rate. 

It is possible to purchase HEPA filters at hospital standard however for an ordinary job, a retail HEPA filter is still effective at removing mold spores from the air. 

How to Choose the Perfect HEPA Filter for Mold Elimination  

There are two distinct HEPA filters. The first is absolute HEPA filters which must pass regulatory tests to be considered HEPA worthy. They are at least 99.97% effective in trapping particles of 0.3 microns and above.  

The second is HEPA-Type filters which often resemble absolute filters but do not hold the same standard. They often capture between 85 to 90% of particles becoming less effective for particles below 1 micron.  

A good place to start is identifying what you need the filter for. If you are looking for an air purifier without a specific necessity then a HEPA-type filter will do the job. If, however, you have a specific mold problem such as Penicillium, then a HEPA filter will be a more confident move.  

Budget is an important aspect to consider as absolute HEPA filters will fetch a higher price than HEPA-type filters as well as the maintenance of replacing filters and the potential installation costs adding to the bill.  

Choosing the right size HEPA filter for your need will aid its efficiency as a small to medium size filter will satisfy use for ordinary purposes whilst being quieter and less expensive. However, if a large one is necessary, it may be worth seeking professional advice on what filter will be the most efficient.  

Scroll to Top