Indoor Air Measurement: Mould Air Sampling with Total Spore Count

Spore trap at 15 l/min, total spore count in the lab, spores/m³ against an outdoor reference – the method, the standards, the limits.

What an air sample measures

An air sample measures the concentration of mould spores and other particles in the air of a room at the time of sampling – in spores per cubic metre, by genus, compared with the outdoor air. It answers the question "is there a source of spores in this room?" A surface test answers a different question: "what is growing on this spot?" Serious cases need both.

The method: particle sampling with total spore count

Defined volume

A calibrated pump draws a defined volume of air (15 l/min for 5 minutes = 75 litres) through an AirTrap XL spore-trap cassette; particles impact on a gel-coated slide.

Total spore count

The lab counts and identifies all spores on the slide directly under the microscope – viable and non-viable. This is the total spore count principle described in DIN ISO 16000-20; culture-based analysis only shows what grows on a nutrient medium and takes days.

Results

Spores/m³ per genus, indoor versus outdoor reference, with images from the slide.

What makes samples comparable

Sampling volume, flow rate calibration, collection efficiency and cut-off of the cassette, sampling height and room conditions (windows closed 24 h). AirTrap XL is compared with Air-O-Cell on the comparison page.

Two terms that get mixed up

Total spore count, not CFU

AirTrap is particle sampling with total spore count (DIN ISO 16000-20): every spore on the slide is counted, viable or not, and reported in spores/m³. It is not a culture-based air sample and does not report CFU/m³ – the two values are not interchangeable.

Concentration, not presence

A spores/m³ value only means something against the outdoor reference of the same day and the sampling parameters in the report – which is why every submission needs an outdoor sample.

The process on site

Room closed for 24 hours, 5 minutes per room in the breathing zone, one outdoor reference per property, cassettes labelled, registered online and posted. The full routine is on the step-by-step page; what happens in the lab is on the Sporecyte page.

Step-by-step guide

What is Sporecyte?

Standards and framing

Sampling and evaluation follow the German Federal Environment Agency's mould guideline (UBA-Schimmelleitfaden, 2024 edition) – outdoor reference, evaluation logic – and, for clearance after remediation, WTA leaflet 4-12; the VDI 4300 series describes measurement strategies for indoor air. The report documents the sampling parameters so an expert can assess it – it supports an assessment, it does not replace one.

For professionals and businesses

Property managers, remediation contractors and surveyors use air sampling for portfolio checks, clearance measurements and dispute documentation. Cost per sample: the pack price includes the lab analysis; refill packs bring it down at volume.

Order the complete set

What you get back

Frequently asked questions

What does an air sample measure?

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The concentration of spores and particles in the room air in spores/m³ by genus, compared with the outdoor air.

What does an indoor air measurement cost?

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The cassette price includes the lab analysis; a complete set with pump covers eight samples, refill packs lower the cost per sample. Prices in the shop.