Your eyes and nose are the test: mold looks like spots in many colors and smells musty, and the CDC says seen or smelled mold should be removed.
Hunt where moisture lives: under sinks, window frames, bathroom ceilings, basements, old leak sites. The EPA notes mold produces allergens and irritants that can trigger allergies and asthma and irritate airways even in non-allergic people, so symptoms that ease away from home are a hint. Skip the air test kit: the fix is the same whatever the species. Find and fix the moisture source, and treat anything beyond a small patch, roughly 10 square feet per EPA guidance, as a possible professional job.
What to do
Common questions
How do I know if my home has mold?
You find mold with your eyes and nose, not a lab. The CDC says mold can look like spots of many different colors and can smell musty, and if you see or smell it, you should remove it. Where to look: wherever moisture lingers. Behind and under sinks, around window frames with condensation, on bathroom ceilings and grout, in basements, on the cold side of exterior walls, around AC units, and anywhere a leak ever happened, since mold follows water. The health context from the EPA: molds produce allergens and irritants, and inhaling or touching spores can trigger allergic reactions in sensitive people, irritate eyes, skin, nose, throat, and lungs even in non-allergic people, and provoke asthma attacks in people with asthma. So persistent sneezing, coughing, or wheezing at home that eases when you are away is a soft signal worth pairing with an inspection. Do not bother with air sampling kits as a first step: health agencies do not recommend routine mold testing because any visible or smelled mold needs removing regardless of species. What matters is finding the moisture source, because cleaning without fixing the damp means the mold returns, and an area bigger than about 10 square feet, per EPA guidance, is where you start thinking about professional help.