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Complete Guideline to Black Molds in Air Ducts

Barry Martin
April 6, 2022

Black mold is one of the toxic types of molds that can grow inside your air vents. Black mold was first discovered in Prague in 1837 by a Czech mycologist. Black molds are very harmful. Your body can feel sick with the presence of black mildew. If you have black mold in air ducts, you need to take cleaning measures as soon as possible.

What is Black Mold?

Black mold belongs to the type of mold species called Stachybotrys chartarum. It has a greenish-black color. This type of mold only grows in specific environments like high moisture, low nitrogen, and sunlight-free areas. It can grow fast in water-damaged houses, wood partitions or floors, papers, etc. Stachybotrys prefer humidity levels over 90%.


What Causes Black Mold in Air Vents & Ducts?

The most common reason behind black molds inside the air ducts is moisture. As the cool air flows through the vent, the humidity increases inside the air vent. These molds are generally airborne. The condition needs to be treated right after you figure out the growth of molds.

If you have water damage or leakage in your workplace, you are highly likely to get molds. Most molds may begin right after getting in contact with water for 24 to 48 hours, but black molds take several days to grow.

Signs of Black Mold in Air Duct



The first sign is a musty odor. The smell gets more potent if the mold is not treated. It may then be more challenging to check for mold in the air ducts. If you can smell the foul odor across your house, maybe it's time to have a check for black molds.


The presence of black dust is also a sign of molds in air vents. This dust is quite toxic. Cleaning out black mold is not as simple as it may seem. It has a long-term effect. Only cleaning dust out of your room is not enough. You must contact the HVAC unit to prevent the mold from spreading further.

Health Symptoms

Black mold comes with some severe health conditions. You may face fatigue, tiredness, nausea, headache, and several other symptoms when turning your HVAC system on. Some people also notice allergic reactions.

Studies have shown that black molds can cause upper respiratory tract problems. However, more research needs to be done to determine the exact health effects of black molds.

Visible Signs

It's easy to spot black molds if they grow on a surface. You can see visible molds around your shower wall, air vents, floors, and ceilings. Black molds can have different textures. The color can be black or dark greenish with a yellow exterior.

How to Remove Black Mold in Air Ducts?


Black molds contain biological risks. You must wear protective gear while removing black molds from air ducts. You should wear a mask and hand gloves. If you have health issues like asthma, COPD, or allergies, we recommend you not to attempt this task by yourself. We will discuss a few expert tricks for removing black molds in air vents.

Home remedies

You can remove black molds with the tools available at your home. We recommend this solution for minor mold attacks only. With laundry detergent, baking soda, dish soap, vinegar, and bleach, you can use this same method.

Step 1: Turn the air conditioning off before starting the cleaning process
Step 2: Take a large bowl and make a mixture of the solution you will be using. Mix laundry detergent, bleach, or other available things with water. Use warm or hot water. Boiling water is also helpful in killing black molds. Bleach is known to kill the molds faster.
Step 3: If you are cleaning mold out of a surface, scrub the area. You can unscrew the vent for air vents and spread the mixture inside. You can spray the solution first if the affected area is not accessible for you to reach.
Step 4: Let the solution stay at least 15 minutes.
Step 5: Take a long brush to scrub inside of the air vents
Step 6: Let the wet surface dry thoroughly
Step 7: Once it is dry, set back the air duct

Use Mold Removal products.

Mold removal products usually come with instructions on the packaging. These are chemical-made cleaners that can help you to kick the molds and mildew stains out completely. Most of the solutions come like sprays.

Step 1: Spray the mold removal on the affected area
Step 2: Wait for a while as instructed with the product
Step 3: You do not need to do the scrubbing with a high-functioning formula. Wipe the area with a cloth or paper.
Step 4: Rinse the area with warm water
Step 5: Let it dry

How To Prevent Black Mold in Air Vents?

Good ventilation

Good ventilation is vital for every household. It enriches the circulation of airflow, which may reduce humidity. Mold prefers a closed environment. The molds will have difficulties growing if you have proper ventilation.

Regular Filter Changes

We recommend you check your filters every three months. It will keep healthy airflow inside your home. Your filter may collect pathogens and let the black molds grow inside if you use it for a long time.

If you notice black spots around your filter, it may have caught black molds already. You can either clean the molds or replace your filters. It would be best to consider replacing your filter every three to twelve months, depending on the condition.

HVAC UV Lights

HVAC UV lights produce some energy that can penetrate the mold. Using HVAC UV light will stop the molds from growing. It's not organically poisonous, but it will eliminate spores alongside other microorganisms, viruses, and volatile organic compounds.

Repair Leak

Black molds have tendencies to grow on wet surfaces. Regular check if you have any leakage areas at your home. Make sure you repair them on time before getting molds.


Get Help From an Expert

Black molds can be very unsafe sometimes. You can remove the molds yourself, but we recommend you get a professional hand involved. Get it done without putting yourself at risk.

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