Does UV Light Kill Mold?

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Written By Jamila W.
UV light

Molds are fungi that grow from microscopic spores, and they’re everywhere.

According to statistics, around 70% of homes have mold inside them. This makes life for people with breathing conditions such as asthma and allergies much harder. If you’ve been searching for ways to deal with your mold problem, you might have googled:

Does UV light kill mold?

The short answer is – Yes, properly installed ultraviolet light is successful in killing mold.

To learn more about UV light, how it kills mold, and the risk factors that are associated with mold growth, scroll down.

Ultraviolet Light 101

Does UV Light Kill Mold?

UV light is part of the electromagnetic spectrum, and its extension depends on the wavelength. This is a type of light that can’t be detected by the human eye. Instead, a bluish light will be visible through a filter of the lamp.

This ultraviolet electromagnetic radiation comes from a variety of sources, such as the sun and other artificial sources. It can be divided into three groups:


Shortwave UV light is the farthest from the visible light. It’s shorter than rays of sunlight, and it’s recognizable for its ability to fluoresce different minerals for chemical analysis and germicidal effects.

This UV light extends from 100 to 280 nm.


Midrange UV light is the shortest wavelength found in sunlight. This group is most commonly used to fluoresce substances more effectively. Also, this UV light can cause severe sunburn if you’re near it for too long.

This UV light extends from 280 to 320 nm. Its peak energy is at 302 nm.


Longwave UV light is the nearest to the visible light. Also referred to as black light, it successfully activates fluorescence in manufactured materials and a number of natural substances.

This UV light extends from 320 to 400 nm.

UV Light Application: Where Is It Used?

UV lights, which are typically placed in lamps, can be used for a number of purposes:

  • Mold treatment
  • Bacteria and virus disinfection
  • Coating, ink drying, and curing
  • Tanning
  • Hygiene control
  • Fluorescent inspection
  • Water purification

The Health Risks of Mold

mold, sink

The health risks associated with exposure to mold are numerous, and people who are already dealing with respiratory issues are at greater risk of experiencing severe symptoms.

Here are the symptoms associated with inhaling or touching mold spores within your household:

  • Sore throat
  • Runny nose
  • Sneezing
  • Coughing
  • Headache
  • Lung irritation
  • Wheezing
  • Eye irritation

While most people will experience only mild allergic reactions to mold, those with respiratory issues may be at risk of the following

  • Infections (histoplasmosis, valley fever, sporotrichosis, aspergillosis)
  • Asthma
  • Pneumonitis
  • Compromised immune system
  • Sarcoidosis
  • Cystic fibrosis
  • Tuberculosis

People that fall under the risk category of developing severe symptoms include:

  • People with a family history of allergy and asthma symptoms.
  • People employed in a work environment that’s exposed to mold (farmers, woodworkers, winemakers, lumber millers).
  • People who live in an environment that’s been flooded recently, have leaky pipes or poor ventilation systems.
  • People who live or work in a building that has more than 50% humidity.

How To Recognize Mold

It’s important to mention that mold can be white, spotted, black, or any other color. If you’re not certain whether it’s an old stain or a mold issue you’ve just seen on your wall, for example, here are the signs that might help you:

  • A musty, earthy smell
  • A nearby source of moisture
  • Cracking, peeling, or warping the material it’s growing on
  • A drop of bleach lightens its color
  • Continues to grow after some time

How common is mold?

It’s actually more common than you might think.

  • At least 45 million buildings in the US have a mold issue.
  • Canadian experts have uncovered 270 different mold species.
  • The most common type of mold is black mold.

Is UV Light Effective in Killing Mold?

home, interior
Yes – UV light kills mold, and it’s highly effective.

Although it can be placed anywhere in your household, it’s most commonly used within air conditioning devices. Many industries actually use UV lights for the purpose of microbial decontamination for water treatment, air purification, and other medical purposes.

When ultraviolet light is set to short wavelength frequencies, it has germicidal effects, which means that it’s effective in eliminating germs. These shortwave frequencies are also used for destroying mold.

The reason UV lamps are effective in destroying mold is that the entire room where the light is used is blanketed by that UV light. This allows the whole area to be disinfected. Moreover, ultraviolet lamps are much more effective than traditional methods of cleaning, such as using vinegar, because they’re not as time-consuming.

The ultraviolet light in your HVAC system can keep the entire room free from mold.

Bear in mind that the effectiveness of UV lights depends on the time length the room has been exposed to this light and its intensity.

Logically, UV lamps with higher intensity are more efficient in killing mold.

Killing Mold With UV Light: The Steps Explained

home, interior
Here are the three simple steps to kill mold with UV light:

Firstly, you should get a UV-C lamp, depending on the size and range that fits your budget and room.

Secondly, you should identify the surfaces that need UV light exposure. Make sure to be thorough and inspect every corner of your home because, whichever spot you miss, mold will continue to grow and spread.

Thirdly, place your UV light approximately two inches away, and turn it on. Leave the light on, and leave the room for a period of 1-2 hours. Repeat the process for any surface and room.

Bonus tips:

In order for your UV light to kill mold effectively, every other light needs to be turned off. This doesn’t only include lightbulbs but all the light that may come in from windows and doors.

Make sure to use personal protective equipment when dealing with UV lights.

Although there are glasses that can protect you from ultraviolet radiation, you should steer clear of this light, especially if it’s highly intensive. Also, you should wear gloves whenever you handle a UV light bulb.

Advantages of Using UV Light To Kill Mold

Here are the main advantages of using UV lights to kill mold:

  • UV lamps are able to kill mold more rapidly than traditional cleaning methods.
  • UV lamps are more effective than alternative methods.
  • Using UV lamps to destroy indoor biological pollutants allows you to avoid harsh chemicals.
  • A UV light source should eliminate 99.9% of mold spores.
  • Household UV lamps significantly reduce smells and odors that come from dead mold spores.
  • Ultraviolet energy helps maintain a cleaner coil.
  • UV C lamps reduce clogs in your drain lines by preventing algae growth.

Disadvantages of Using UV Light To Kill Mold

Here are a couple of disadvantages of using a UV lamp to kill mold in your household:

  • The lights need to be applied to every surface where mold is present.
  • UV C light must be placed at the appropriate distance in order to work.
  • Most household UV lamps can be quite expensive.
  • An ultraviolet lamp can be harmful to the naked human eye and can cause sunburn.

Using UVGI Cleaners for Mold Treatment

home, interior
If your goal is improved indoor air quality, you should consider using Ultraviolet Germicidal Irradiation Cleaners (UVGCI).

Also referred to as UV cleaners, their aim is to destroy bacteria, biological pollutants, and other microorganisms with ultraviolet radiation from UV lamps placed in HVAC systems.

The UV light breaks apart the molecular DNA that penetrates deeply the membrane and nucleus. The light renders the microbes, making them unable to reproduce.

In most cases, a professional will help you with installing a UV light system in your household. However, you are responsible for changing the filters regularly.


Here are more questions that might have popped up while reading about mold treatment with UV light:

Does UV Light Kill Mold Smell?

Yes. UV lights are one of the simplest ways to keep unhealthy indoor smells under control. When exposed to UV rays, these microbes lose their ability to reproduce, which directly contributes to the suppression of unpleasant odors.

Is the Smell After UV Treatment Safe?

Although the smell after UV treatment is completed may not be harmful, it’s still recommended to leave the room for other health reasons.

Do Germs Glow Under UV Light?

Yes. In most cases, germs will illuminate after being exposed to UV radiation.

How Much Can a UV Light Cover?

For example, a 30-watt lamp can cover approximately 200 feet. This is why it’s important to measure the area where mold has accumulated precisely.

What Is the Best Way To Use UV Light to Kill Mold?

The best way would be to obtain a professional-grade unit that uses a combination of UV lamps and filters.

How Long Can Mold Stay in Your Household?

Mold can stay in your home indefinitely, which makes mold inspection an essential check-up for all homeowners.

Summing Up: UV Light Killing Mold

By now, you had the opportunity to learn more about does UV light kill mold and much more. Here are the key takeaways:

Ultraviolet light is an electromagnetic spectrum that can’t be detected by the human eye, and it can be divided into short, midrange, and long waves. All of these wavelengths are successful in killing mold inside your household.

Mold is actually more common than you might think, and it can cause a number of health hiccups, from mild allergic reactions to serious issues such as asthma and tuberculosis.

In order to kill mold with a UV lamp, you must identify the area, place the lamp at an appropriate distance, and leave the room. Also, wearing protective gear is inevitable.

UV light treatment brings many benefits, such as time efficiency, cleaner coil, improved indoor air quality, and so on. The best way to get rid of mold with UV treatment is to obtain UVGCI cleaners.

However, you should be mindful of changing the filters regularly and protecting your vision and skin from this intensive light.