Mold & air quality 6 min · updated 2026

Indoor air quality testing in the Bay Area: what it measures

A plain-language guide to residential air quality testing for mold.

Short answer

A residential air quality test for mold captures airborne spores on spore-trap cassettes inside the home and outside at the same time. The lab counts and identifies spores in each sample. When indoor counts are clearly higher than outdoor, or indoor air contains species like Stachybotrys or Chaetomium, there is likely a hidden indoor source.

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Key takeaways

  • Outdoor control is essential.
  • Species matter as much as totals.
  • Results vary with weather, so both samples are taken together.
  • Report is useful for landlords, buyers and insurers.

How samples are collected

A calibrated pump pulls a measured volume of air through a cassette for several minutes in each room of concern and once outside.

How to read results

Look at total spores per cubic meter indoors versus outdoors, then at which species are present. Water-damage indicator species indoors are a red flag even at lower counts.

Infographic

How a Bay Area mold test works

From order to written lab report.

  1. 1Order

    $495

    $545 − $50 online

  2. 2Visit

    Same day

    Moisture check + air samples

  3. 3Lab

    Accredited

    Spores counted and identified

  4. 4Report

    Next day

    Indoor vs outdoor comparison

Customer reviews

Rated 5.0 out of 5 across every metro we cover

86 verified reviews from homeowners, property managers, contractors and insurance adjusters who needed certified answers fast.

5.0

86 reviews

  • 5 out of 5 stars

    Bilingual and respectful

    They explained everything to my parents in Spanish and English. Very patient team.

    Gloria M. · Oklahoma City ·

  • 5 out of 5 stars

    Reliable

    Easy scheduling, clean report formatting. We will use them again on the next unit turn.

    Aaron S. · Louisville ·

  • 5 out of 5 stars

    Bathroom remodel cleared

    Old sheet vinyl and backer board both sampled. The report cited the exact layers so the tile crew knew what to do.

    Jessica T. · Omaha ·

  • 5 out of 5 stars

    Straight answers

    No scare tactics, no vague pricing. He told me what testing could and could not tell me before I paid a dime.

    Marcus B. · Boise ·

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FAQ

Indoor air quality testing: common questions

Does an air test find mold in walls?

It can detect spores escaping from hidden growth, which is often how hidden mold is found.

Is fog-season air in San Francisco a problem for testing?

No, because the outdoor control is taken at the same time and weather affects both.

Do you also remove mold or asbestos?

No. We only test, so the report is independent and you can hire any remediation or abatement company you choose.

How we compare

What you actually get in every metro we cover

Asbestos testing service comparison
ProviderHow you get a priceTurnaroundNotes
Typical local labQuote by email, days later3-4 business daysRush turnaround costs extra
Abatement contractorFree test bundled with a bidVariesIncentive to find a problem
Rapid EnvironmentalFree quote on the phone in 2 minutesFast accredited turnaroundTesting only · $50 OFF today

Every job is scoped by the number of distinct materials being disturbed, so we quote it by phone instead of posting a number that will not match your project. Call (916) 252-1003 and $50 off today comes off the booking.

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Glossary

Asbestos terms your contractor and lab report will use

ACM
Asbestos-containing material — any material with more than 1% asbestos by weight.
PACM
Presumed asbestos-containing material — older suspect material treated as positive until testing proves otherwise.
Friable
Material that can be crumbled by hand pressure and therefore releases fibers easily.
Non-friable
Asbestos locked in a hard matrix such as floor tile or stucco; hazardous mainly when cut or broken.
PLM
Polarized Light Microscopy, the standard laboratory method for identifying asbestos in bulk building samples.
Point count
A more precise PLM technique used when asbestos content is near the 1% regulatory threshold.
Homogeneous area
A group of material that is uniform in color, texture and installation date — each one needs its own sample.
Chain of custody
The signed record tracking a sample from collection to laboratory analysis.
Chrysotile
White asbestos, by far the most common type found in most states residential materials.
Amosite
Brown asbestos, typically found in insulation board and thermal products.
Encapsulation
Sealing or covering asbestos material in place instead of removing it — often the cheapest compliant option.
Abatement
Licensed removal of asbestos material under containment, performed by a certified abatement contractor.
NESHAP
Federal air standard requiring an asbestos inspection and notification before most renovation work.
your state environmental agency
state Commission on Environmental Quality, the state agency enforcing asbestos and renovation air rules in most states.
DSHS
state Department of State Health Services, the state agency that licenses asbestos consultants and enforces the state asbestos rules.