CMA CMA Sampling & Testing Methods 1 — Questions and Answers
Question 1: Which air sampling method collects mold spores on a glass slide coated with adhesive for direct microscopic examination?
- Impaction sampling (e.g., Andersen, RCS) (Correct answer)
- Impingement sampling
- Filtration sampling (cassette)
- Settle plate sampling
Correct answer: Impaction sampling (e.g., Andersen, RCS)
Impaction samplers like the Air-O-Cell or Burkard draw air through a slit, impacting particles onto an adhesive-coated slide for microscopic analysis.
Question 2: What is the primary advantage of bulk sampling compared to air sampling when assessing mold in building materials?
- Bulk sampling is faster to collect
- Bulk sampling identifies the fungal species present in the material itself (Correct answer)
- Bulk sampling captures airborne spores more accurately
- Bulk sampling requires no laboratory analysis
Correct answer: Bulk sampling identifies the fungal species present in the material itself
Bulk samples (pieces of building material) allow laboratories to identify and quantify fungi actually colonizing the material, not just what is airborne.
Question 3: What does the term 'colony forming unit' (CFU) represent in mold culture analysis?
- The number of individual spores in a sample
- A single viable propagule capable of growing into a visible colony (Correct answer)
- The weight of mold biomass per square centimeter
- The ratio of mold to non-mold particles in air
Correct answer: A single viable propagule capable of growing into a visible colony
A CFU is one countable mold colony that grew from a single viable fungal structure (spore, hyphal fragment, etc.) — it represents viability, not total spore count.
Question 4: Which analytical method can identify mold genera and species using DNA without requiring laboratory culture growth?
- Direct microscopy (spore trap analysis)
- Culture-based analysis (MEA plates)
- qPCR (quantitative polymerase chain reaction) (Correct answer)
- Tape lift with KOH preparation
Correct answer: qPCR (quantitative polymerase chain reaction)
qPCR detects and quantifies specific fungal DNA sequences, allowing identification of species including those that do not culture readily.
Question 5: What is an 'outdoor control' (background) sample, and why is it required during an indoor mold assessment?
- A sample from an unaffected room to compare with the problem area
- An outdoor air sample collected simultaneously to establish baseline spore levels (Correct answer)
- A sample taken before remediation to document pre-cleaning conditions
- A quality control sample sent blank to the laboratory
Correct answer: An outdoor air sample collected simultaneously to establish baseline spore levels
An outdoor control sample establishes the background spore types and concentrations so that indoor levels can be meaningfully compared to determine if there is an indoor amplification problem.
Question 6: Which sampling media is most commonly used for viable (culture-based) mold air sampling?
- Polycarbonate filter cassettes
- MEA (Malt Extract Agar) or DG-18 agar plates in an Andersen sampler (Correct answer)
- Air-O-Cell spore trap cassettes
- Cyclone collector tubes
Correct answer: MEA (Malt Extract Agar) or DG-18 agar plates in an Andersen sampler
Viable air sampling uses nutrient agar plates (MEA, DG-18, or similar) in cascade impactors like the Andersen 6-stage sampler to grow and count living fungi.
CMA CMA Sampling & Testing Methods 1
Which air sampling method collects mold spores on a glass slide coated with adhesive for direct microscopic examination?