What's That Smell?
Your nose is the first warning system. Every unusual indoor odor has a cause — and many are dangerous.
Select the smell you noticed to identify the hazard.
Musty or Damp Smell URGENT
A musty smell almost always means mold is growing nearby, even if you can't see it. Mold behind walls, under flooring, or in HVAC systems produces microbial volatile organic compounds (MVOCs) that create this distinctive odor.
Possible Hazards:
Mold Exposure
chronic coughing, wheezing, nasal congestion
High Indoor Humidity
musty smells, condensation on windows, warped wood
What to Do:
- • For Mold Exposure: Fix water leaks within 24-48 hours. Maintain indoor humidity below 60% (ideal: 30-50%). Clean visibl...
- • For High Indoor Humidity: Use dehumidifiers in damp areas. Run exhaust fans in bathrooms and kitchen. Fix leaks promptly. Ensu...
Recommended Products:
Rotten Egg Smell EMERGENCY
A rotten egg or sulfur smell can indicate a natural gas leak. This is an EMERGENCY. Leave the house immediately and call your gas company. Gas companies add mercaptan to make natural gas detectable by smell.
⚠️ EMERGENCY ACTION
If you smell rotten eggs or suspect a gas leak: evacuate immediately, do not use light switches, and call your gas company or 911 from outside.
Possible Hazards:
Gas Stove Emissions (NO2 and Benzene)
asthma attacks, coughing, wheezing
Attached Garage Air Contamination
headaches, dizziness, nausea
What to Do:
- • For Gas Stove Emissions (NO2 and Benzene): Always use range hoods when cooking. Open windows while using gas appliances. Consider switching to ...
- • For Attached Garage Air Contamination: Never idle a car in an attached garage, even with the door open. Seal the door between garage and ho...
Recommended Products:
Chemical or Paint Smell INVESTIGATE
Chemical odors indicate VOC off-gassing from paints, new furniture, cleaning products, or building materials. These compounds can cause headaches, dizziness, and long-term health effects.
Possible Hazards:
Volatile Organic Compounds (VOCs)
headaches, dizziness, nausea
Paint Fumes and Off-Gassing
headaches, dizziness, nausea
Formaldehyde (VOC)
burning eyes, throat irritation, coughing
What to Do:
- • For Volatile Organic Compounds (VOCs): Use low-VOC or zero-VOC paints and products. Increase ventilation when using products containing VOC...
- • For Paint Fumes and Off-Gassing: Choose zero-VOC paints. Ventilate painted rooms for at least 72 hours. Use fans and open windows. Wa...
- • For Formaldehyde (VOC): Increase ventilation when bringing new pressed wood products home. Use exterior-grade pressed wood p...
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Sweet or Fruity Smell EMERGENCY
A sweet smell near gas appliances could indicate incomplete combustion producing carbon monoxide. CO is mostly odorless but some combustion byproducts have a faint sweet smell. Treat as an emergency.
⚠️ EMERGENCY ACTION
If you smell rotten eggs or suspect a gas leak: evacuate immediately, do not use light switches, and call your gas company or 911 from outside.
Possible Hazards:
Carbon Monoxide (CO)
headache, dizziness, nausea
Attached Garage Air Contamination
headaches, dizziness, nausea
What to Do:
- • For Carbon Monoxide (CO): Install CO detectors on every level of your home and outside sleeping areas. Never run generators in...
- • For Attached Garage Air Contamination: Never idle a car in an attached garage, even with the door open. Seal the door between garage and ho...
Recommended Products:
Stale or Dusty Smell MONITOR
Stale air indicates inadequate ventilation. Dust mites, pest allergens, and CO2 build up in poorly ventilated spaces. This is common in modern energy-efficient homes that are too well-sealed.
Possible Hazards:
Poor Ventilation (Stale Air)
headaches, fatigue, difficulty concentrating
Dust Mite Allergens
sneezing, runny nose, itchy watery eyes
Cockroach and Pest Allergens
asthma attacks, chronic cough, nasal congestion
What to Do:
- • For Poor Ventilation (Stale Air): Open windows daily when weather permits. Use exhaust fans in bathrooms and kitchen. Consider an HRV ...
- • For Dust Mite Allergens: Wash bedding weekly in hot water (130°F). Use allergen-proof mattress and pillow covers. Maintain hu...
- • For Cockroach and Pest Allergens: Seal cracks and openings around pipes. Store food in sealed containers. Remove garbage daily. Fix wa...
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Burning or Metallic Smell EMERGENCY
A burning smell with no obvious source could mean electrical overheating or a furnace problem producing CO. If you smell burning metal or plastic with no visible source, evacuate and call 911.
⚠️ EMERGENCY ACTION
If you smell rotten eggs or suspect a gas leak: evacuate immediately, do not use light switches, and call your gas company or 911 from outside.
Possible Hazards:
Carbon Monoxide (CO)
headache, dizziness, nausea
Gas Stove Emissions (NO2 and Benzene)
asthma attacks, coughing, wheezing
What to Do:
- • For Carbon Monoxide (CO): Install CO detectors on every level of your home and outside sleeping areas. Never run generators in...
- • For Gas Stove Emissions (NO2 and Benzene): Always use range hoods when cooking. Open windows while using gas appliances. Consider switching to ...