Mold is a type of fungus found naturally in both indoor and outdoor environments. Tiny particles called spores travel through the air constantly — and when they land on a wet or damp surface indoors, they can begin to grow and spread.
According to the U.S. Environmental Protection Agency, mold is not typically a problem unless it begins growing indoors. The key to controlling it is controlling moisture.
In South Florida, that’s easier said than done. With average humidity levels regularly exceeding 70%, mold doesn’t just show up after a flood or a leak — it can grow behind walls, under floors, inside AC ducts, and in any space where moisture lingers.
Particulate matter refers to tiny solid particles that float through the air inside your home. They’re often invisible to the naked eye but can circulate through your HVAC system, settle into ductwork, and accumulate in living spaces over time.
Common sources include dust and household debris, smoke and combustion particles, construction dust, fibers from carpets and upholstery, silica from building materials, and outdoor pollution that drifts in through doors and windows.
Gaseous pollutants are invisible contaminants that can’t be seen or smell — at least not always.
Common examples include carbon monoxide from fuel-burning appliances, carbon dioxide from poor ventilation and human respiration, volatile organic compounds (VOCs) from paints, cleaning products, and furniture finishes, and off-gassing from flooring, adhesives, and building materials.
Allergens are substances that trigger immune responses in people who are sensitive to them.
Common indoor allergens include pollen that enters through doors and windows, pet dander from dogs, cats, and other animals, dust mite debris, and insect fragments and other organic particles that accumulate in the home.
Biological contaminants are living or once-living microorganisms that become airborne indoors.
This category includes mold spores, bacteria, Legionella associated with water systems and cooling equipment, and fungal fragments and other microbial debris.
We’re here to help. Whether you’re trying to learn about pollutants in your home or workplace, or just want to point us toward a topic you’d like us to cover — we’d love to hear from you.
South Florida Indoor Air is an independent educational resource dedicated to helping our community breathe better and make informed decisions about the air inside their spaces.