A Description & Critique of Contemporary Indoor Mold Sampling/Collection/Testing Methods Air samples to “test” for mold A collection device, slide, cassette, or tape are used with a calibrated air pump to collect airborne particles. we are not referring to culture plates which rely on passive collection or settlement of particles as these have even worse inaccuracies and errors than the reservations I describe about active air sampling described here. Some common examples of air samplers include:
Impaction samplers (Burkard™, Allergenco™) collect airborne particles through a venturi-slit onto a prepared microscope slide using a equipment incorporating a calibrated air pump and a static or moveable slide permitting single-use or time-lapse sampling. Cassette samplers (Air-o-Cell™) use a patented 37mm cassette connected to a calibrated pump (typically at 15 lpm). The cassette is used to collect airborne particles through a venturi-slit onto a proprietary media on a cover-slip which is in turn mounted onto a microscope slide in the laboratory. Cassette samplers using an MCE filter cassette connected to a calibrated pump. The filter can be cleared and examined microscopically (qualitatively, counting is tough except with the Bi-Air™), or used to prepare a culture, or both. Cassette-like samplers use a calibrated pump connected to a patented stainless steel venturi-device which accepts a microscope slide prepared with a collection media. Anderson-type samplers which collect particles directly onto a culture dish – for “viable sampling” to “test” for mold. Culture samples may be useful in some cases to better identify or to speciate mold which has already been found in a large reservoir. Otherwise it has limitations we discuss elsewhere in this document. Anderson-type impaction samplers which collect particles on tape wrapped around on a drum or Rotorod samplers which collect particles on glass rods are used for outdoor pollen and spore counting and reporting in the IAAA allergy network. They are not well-suited for indoor Building assessment though some folks use the high-error rotorod sampler indoors. Shortcomings of air sampling for mold – some specifics But as a “mold test” for the presence or absence of a mold problem in a Building, a negative air sample result is of little confidence. As a measure of “mold exposure” quantitative analysis (spores/cubic meter) is invalid unless long-term time-weighted average measurements are made under all varying Building conditions. While this is an important diagnostic tool, and one which we apply regularly, it cannot be relied alone on in the way some investigators would use it: dashing into a Building and grabbing an air sample.