How sampling works
What Mold Testing in Haleyville, AL Really Measures
Mold testing is lab science. The most common air method uses a spore-trap cassette on a calibrated pump. A typical run is 15 liters per minute for 5 minutes, so 75 liters of air pass over an adhesive strip inside the cassette. The lab counts and identifies what landed on that strip under a microscope, then converts the count to spores per cubic meter of air.
Indoor numbers mean almost nothing on their own. Outdoor air always carries spores, which is why a control sample gets taken outside during the same visit. The analysis uses rank order: indoor air in a healthy house usually mirrors the outdoor mix at lower numbers, so a spore type that tops the indoor list but barely appears outside is a red flag. There are no federal numeric limits for indoor spores, which is exactly why the outdoor comparison carries so much weight.
When there's a visible spot and you want it identified, surface samples come in. A tape-lift presses clear adhesive tape onto the growth, a swab works on rough or curved surfaces, and a bulk sample is a cut piece of drywall, carpet or insulation sent whole. A wall-cavity air sample, drawn through a tiny hole, can show whether a closed cavity is loaded with spores. Most Haleyville callers want testing for paperwork: a real estate disclosure, a tenant complaint, or proof a cleanup worked.