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When should I worry about mold exposure?

Mold exposure is a common problem that can affect your health and home. Mold spores are tiny particles found both indoors and outdoors that can trigger allergic reactions and respiratory problems. In some cases, mold exposure can lead to more serious health issues. Knowing when to worry about mold exposure is important to protect your health.

What is mold?

Mold is a type of fungus that grows in damp, warm environments. Outdoors, mold plays an important role in nature by breaking down dead organic matter. Indoors, mold growth should be avoided as it can damage buildings and cause health issues.

There are thousands of species of mold. Some of the most common indoor molds include:

  • Cladosporium
  • Penicillium
  • Aspergillus
  • Alternaria
  • Stachybotrys (also known as black mold)

Mold produces microscopic spores that are released into the air. When inhaled, these spores can trigger allergic reactions in sensitive individuals. Mold spores are present everywhere, both indoors and outdoors, but exposure levels are generally higher indoors where mold is actually growing.

What causes mold to grow in my home?

For mold growth to occur, all that is needed is a food source, warmth, and moisture. Indoors, mold can grow on cellulose-based materials such as wood, paper, carpet, drywall, and insulation when excess moisture is present.

Some common causes and sources of excess moisture leading to mold growth include:

  • Flooding
  • Leaky roofs
  • Plumbing leaks
  • Overflow from sinks, showers, bathtubs, or toilets
  • High indoor humidity
  • Damp basements or crawl spaces
  • Steam from cooking or showering
  • Wet clothes drying indoors or clothes dryers exhausting indoors

How am I exposed to indoor mold?

You can be exposed to mold through:

  • Breathing in mold spores: Spores become airborne when mold is disturbed. Activities such as sweeping or vacuuming moldy areas can stir up spores. Mold growth inside HVAC systems can also spread spores throughout a building.
  • Touching moldy items: Mold spores can get on skin and clothes through direct contact with moldy surfaces. Touching moldy items can also stir spores into the air.
  • Eating moldy foods: Some foods may contain mold. Eating spoiled produce, grains, nuts, or fermented foods with mold can cause exposure.

Can mold exposure affect my health?

For most people, limited exposure to mold spores indoors poses little to no health risk. However, mold exposure can cause various health effects in some individuals:

  • Allergic reactions – Symptoms may include runny nose, eye irritation, coughing, nasal congestion, skin rash or hives.
  • Asthma attacks – Mold exposure can trigger asthma symptoms like shortness of breath, wheezing, and chest tightness in those with asthma or mold allergies.
  • Respiratory problems – Fever, shortness of breath, and respiratory infections have been reported in those with chronic exposure.
  • Hypersensitivity Pneumonitis – An immune response to repeated mold exposure that causes lung inflammation and breathing problems.

Those with weakened immune systems, chronic lung diseases, or open wounds are at higher risk of infection from certain mold types like Aspergillus. In rare cases, mold exposure has been linked to hemorrhage, memory loss, and death.

Are some molds more hazardous than others?

Most common indoor molds are generally not hazardous for healthy individuals at typical background levels. However, a few types of mold can produce toxic substances called mycotoxins that may cause illness under the right conditions:

  • Stachybotrys chartarum (also known as black mold) – Mycotoxins from this mold may cause respiratory problems and inflammation.
  • Aspergillus – Mycotoxins from Aspergillus can be associated with disease in those with weakened immune systems if exposure is heavy.
  • Penicillium – Some strains produce mycotoxins but little evidence connects it to disease indoors.

Note that mycotoxins are not always produced, require very high exposure levels, and do not become airborne easily. Overall mold spore exposure, not just mycotoxins, is believed to be responsible for most health effects.

How can I tell if mold is present in my home?

Signs of mold growth in your home may include:

  • Visible mold growth, such as black, green, or white spots, on walls, furniture, or surfaces
  • Moldy, earthy, or musty odors
  • Rotting wood
  • Peeling or curling paint or wallpaper
  • Condensation on windows or walls
  • Water stains on ceilings, walls, or floors
  • Cracked or blistering floors or walls from moisture damage

Even if you cannot see or smell mold, health issues may indicate hidden mold growth. Have an inspection done if mold is suspected but not obvious.

How can I test for mold in my home?

There are several methods to test for mold:

  • Mold inspection – A visual inspection by a professional to find moisture issues and visible mold.
  • Air sampling – Using specialized equipment to collect air samples to analyze total spore levels.
  • Surface sampling – Wiping a swab or piece of clear tape on a surface to collect mold spores for lab analysis.
  • Bulk sampling – Removing a piece of material like carpet or wallboard and sending to a lab to test for hidden mold.

For most homeowners, a visual inspection is sufficient to locate mold issues. Air sampling can help estimate your overall exposure level. Surface or bulk sampling may help identify specific mold types present if necessary.

What level of mold is considered acceptable?

There are no federal limits for acceptable levels of mold indoors. General guidelines include:

  • Total mold spore levels below 10,000 spores per cubic meter of air.
  • Minimal visible mold growth limited to small areas less than 10 square feet.
  • No musty odors or signs of excess moisture or water damage throughout the home.

Keep in mind some mold spores will always be present in the air and eliminating mold entirely is not always possible. The goal is to address high mold levels that can affect your health.

How can I prevent indoor mold growth?

You can help prevent indoor mold growth by:

  • Keeping indoor humidity below 50%.
  • Quickly fixing any water leaks.
  • Using kitchen and bathroom fans to lower humidity.
  • Increasing air circulation with fans or by opening windows.
  • Cleaning and drying any wet spots within 48 hours.
  • Avoiding carpeting bathrooms, basements, or other damp rooms.

Inspect your home regularly for signs of moisture or mold. Clean and disinfect any moldy areas promptly before the problem can spread.

When should I be concerned about mold exposure?

You should be concerned about mold exposure if you notice any of the following:

  • Visible mold growth covering over 10 square feet in your home.
  • Musty, earthy, or foul odors present.
  • Unexplained health issues like respiratory problems in you or your family.
  • Signs of excess moisture or water damage in your home.

Large mold infestations, mold growth near air ducts, and mold exposure affecting your health are situations that require immediate action.

How should I clean up small mold problems?

For small areas of mold growth less than 10 square feet, you may be able to clean up mold yourself. Take precautions to limit your exposure and contain spores:

  • Wear protective gear – goggles, gloves, and a respirator mask rated N-95 or higher
  • Isolate the area by sealing vents and doors with plastic sheeting.
  • Remove all visible mold and disinfect surfaces with bleach solution or other biocides.
  • Dry affected areas completely.
  • Keep the area well ventilated.
  • Bag and dispose of all moldy materials.
  • Check that the underlying cause of moisture is fixed.

Never mix bleach and ammonia – this creates a toxic gas. Always follow instructions for safe mold cleanup.

When should I hire professionals for mold removal?

You should hire a mold remediation company if:

  • There is more than 10 square feet of visible mold growth.
  • HVAC systems, carpets, or walls are involved.
  • You have a mold allergy, asthma, or respiratory issues.
  • The water source causing it is unknown.
  • Significant water damage has occurred.
  • You are uncertain about how to properly remove mold.

Extensive mold growth requires professional containment, removal, and cleanup protocols to prevent it from spreading through your home. Trying DIY mold removal for large infestations puts your health at risk.

What does professional mold remediation involve?

A professional mold remediation process includes:

  • Inspection and assessment – Identify the mold type and extent of growth.
  • Containment – Seal off moldy areas with plastic sheeting to prevent spore spread.
  • Removal – Physically remove moldy materials or use biocides to kill mold.
  • Cleaning – Scrub and disinfect all surfaces and materials.
  • Drying – Use equipment like dehumidifiers and fans to fully dry areas.
  • Repairs – Fix any water issues and rebuild damaged structures.
  • Verification – Confirm mold levels are back to acceptable through additional testing.

Professional remediators have specialized tools, protective equipment, and expertise to handle mold removal safely and effectively.

Will homeowners insurance cover mold removal?

Most standard homeowners insurance policies do not cover mold damage or mold removal. However, if the mold growth results from a covered peril like fire damage or pipe bursting, your insurance may pay for mold remediation under those circumstances.

You can add mold coverage to your policy as an add-on or endorsement for an additional premium in most cases. This provides protection if mold develops from non-covered events like high humidity or flooding.

Check your policy language as coverage can vary between providers. Notify your insurance company about suspected mold problems right away.

How can I protect my health from mold?

Steps you can take to protect your health from mold include:

  • Identify and fix any moisture sources allowing mold to grow.
  • Clean up any small areas of mold growth promptly before they spread.
  • Have HVAC systems cleaned and disinfected if contaminated by mold.
  • Consider using a dehumidifier to control indoor humidity.
  • Add filters with a Minimum Efficiency Reporting Value (MERV) rating of 8 or higher to your HVAC system.
  • Get a HEPA air cleaner for your home to filter mold spores.
  • Wear an N95 mask, gloves, and goggles when cleaning moldy areas.
  • See a doctor if you have unexplained health issues that may be mold-related.

Controlling moisture and indoor mold growth, plus limiting your exposure, will help keep your home healthy.

When should I see a doctor about possible mold-related illness?

Consult a physician if you experience any of the following symptoms that may potentially be linked to mold exposure:

  • Coughing, chest tightness, wheezing, or shortness of breath
  • Nasal congestion, sneezing, runny nose, or sinusitis
  • Throat irritation, hoarseness, or sore throat
  • Eye redness, burning, blurred vision, or tearing
  • Skin rashes, hives, or itching
  • Headaches, confusion, or memory loss
  • Fatigue, malaise, nausea, or vomiting

Tell your doctor about any dampness, water leaks, or visible mold in your home. Bring photos and mold testing results if available. Getting a proper diagnosis is key to determine if your health issues stem from mold exposure.


Mold growth is a common problem in many homes. Limited exposure for healthy individuals is usually not a major concern. However, large infestations, mold near air systems, and exposure affecting your health require prompt inspection and remediation. Controlling excess moisture and fixing water leaks prevents indoor mold growth and associated health effects. Seek medical help if you suspect health issues from mold. With vigilance and care, you can protect your home and family from the hazards of indoor mold.