Are microbiological air sampling operations a good idea when assessing mould spores in homes?

We always recommend that you perform microbiological air sampling, even when there is no visible risk of mould spores, but indications show a microbiological risk. Even with medical issues or for the purpose of preservation of evidence, microbiological air sampling may be required. Likewise, we recommend the use of microbiological air sampling, particularly particle collection, during clean-up operations.

Are there limit values for microbiological loads in indoor areas?

There are not currently any limit values (in Germany), but there is a considerable number of guidelines and recommendations. A selection is shown here:

• VDI (German Association of Engineers) Guideline 4300 part 10: "Measurement of indoor air contaminations - measurement strategies when examining mould spores indoors"
• BGIA worksheet 9420: "Methods for determination of the mould spore concentration at the workplace"
• DIN ISO 16000 Part 18: "Detection and enumeration of moulds -- Sampling by impaction" (May 2011 still in draft form)
• DIN ISO 16000 Part 19: "Sampling strategy for moulds" (May 2011 still in draft form)
• DIN ISO 16000 Part 20: "Detection and count of mould spores, determination of the total spore count" (May 2011 version still being planned)
• VDB Guidelines, Volume 2: "Chemical and microbiological examinations"(www.baubiologie.net)
• Working team "Quality assurance – mould spores indoors - detection, evaluation, quality management" by the State public health authority Baden-Württemberg, Germany
• Preventive guidance, examination, evaluation and clean-up of mould spore growth indoors by the Federal Environment Agency of Germany  (www.umweltbundesamt.de)
• Guidance on identifying the cause and cleaning-up in the event of mould spore growth indoors by the Federal Environment Agency of Germany (www.umweltbundesamt.de)
• Standard of biological building SBM-2008 by the Institute of Building Biology + Ecology Neubeuern (IBN) in Germany (www.baubiologie.de)

Which culture media should be used for airborne spore samplings?

When the applicable scope of guidelines does not specify a particular culture medium to use for your examination, we recommend that when examining for mould spores, at each sampling site ensuring the provision of at least one unit of malt extract agar (MEA) and a sample of dichlorane glycerine agar with chloramphenicol (DG18). If the task involved in your examination involves the identification of thermotolerant or thermophilic mould spores, a second air sampling for later cultivation at 37°C is advisable.

How many litres of sample air are required for airborne spore samplings?

The usual quantity of sample air per sampling operation in the summer months ranges from 50 to 100 litres per air sample.
During the winter months, 200 litres per air sample are advisable. For air sampling of thermotolerant / thermophilic bacteria, up to 400 litres per air sample are indicated. If you expect a higher than normal bacterial count (e.g. areas with humidity damage, areas around swimming pools), it is a very good idea to also take an additional sample of 50 litres. The laboratory can then evaluate the "more suitable" sample and avoid the problem of overloaded air samples, which can no longer be evaluated. If you anticipate a very high bacterial count (> 2000 KBE/m³), we recommend using the filtration method involving the sterile gelatine filter with the FA 30 filter adapter or other devices.

What role does the air temperature play when taking an air sample?

The sample air flows in concentrated form in the air sampler on the small areas underneath the nozzles. At lower air temperatures, these regions are partially subject to strong cooling. The viscosity of the culture media increases as the temperature drops. In the worst case, the surface becomes so hard due to the low temperature, that the particles of the air flow bounce off the surface and are carried away with the exhaust air. Fewer particles are separated in this case. If air sampling has to be performed at a temperature below 10°C, this effect should be taken into account during the evaluation.

Why can’t the airborne bacteria collection head LKS100 be used with the separate MP2/39 pump although it is mechanically compatible?

The LKS100 air sampling head is designed for a rated air flow of 100 l/min. The MP2/39 pump conveys, depending on the vacuum, a maximum of 39 l/min. Going below this rated volume flow causes the separating performance of an impactor to decline, which can lead to considerably reduced findings and hence faulty samples. The rated volume flow must always be complied with!

Why can’t I use an activated carbon tube or TENAX tube with the MBASS30?

The air conveying device in the MBASS30 is a high performance fan. Although unlike pumps, fans can generate higher flow rates, they cannot achieve as low a vacuum as pumps. The air resistance of activated carbon tubes is so high, that for the through-flow, higher vacuums are required than is possible with a fans. The high performance fan installed in the MBASS30 is capable of loading close-meshed 80 mm circular gelatine filters.

There are cheaper air samplers than the LKS100 or LKS 30. Why is that?

With a proper technical comparison, you can see that

• some models have "only" 100 jets, meaning that even with microbiological concentrations, this leads to considerable multiple occupancies on bacterial sites and hence reduced findings.
• some models have a significantly inferior filtration efficiency (cut off) or this figure (for good reasons?) is not specified. The filtration efficiency reveals the smallest aerodynamic diameter of particles with a unit density, which are separated with a probability of 50 %. The unit is "dae50". The smaller the number, the higher the separating performance.
• almost all other models "only" support airborne spore sampling. In addition to airborne bacteria collection, our system additionally supports particle sampling and filtration. Using the MBASS30 and the transverse adapter for the air sampler, conveniently and via battery power, a 50 mm PU-foam cylinder for chemical air sampling can also be loaded.
• on many models, no hose connection for sampling of hollow spaces is possible.
• some models do not offer any volume flow adjustment facility, meaning the preselected volume is only attained more or less by trial and error.
• some models are manufactured with defective quality. The components of our products are mostly made in Germany, with the exception of the electronic components and batteries. Our products are exceptionally durable and just as suited to outdoor operation at a building site as a clean room in the pharmaceutical industry.
• For certain models, there is a need to purchase many additional components. We deliver our products in complete sets, software, cable, charger etc. are included in delivery.
• Many providers charge very high prices for their services and what was a supposedly good value device suddenly and unexpectedly becomes something very costly after the 3rd maintenance.

If you take these points into consideration, you will agree that we offer very inexpensive and high quality products.

End FAQ

What are air ions?

Air ions are particles (molecules, particles) in which the number of negatively charged electrons and positively charged protons is unequal due to the donating or receiving of electrons.

Is it true that the natural air ion concentration has continually declined in the last 12 years?

We have also observed a reduction of the natural air ion concentration in recent years. Whereas in 1998, concentrations of 500 to 900 ions/cm³ were still measured, in recent years the total has fallen to 250 to 500 ions/cm³ in the outside air.

In the ionometers used by Holbach GmbH for environmental analysis, a cable for discharging static electricity from the housing is included. Should this cable always be connected?

This discharge facility should be used at all times during operation of the ionometer with connected charger / power supply. The switching power supplies / chargers have an effective capacitive link to the mains. Without the discharge, a high-resistance voltmeter would be capable of measuring alternating voltages of up to 90 volts from the housing to earth. The resulting fields have an influence on the air ions in the vicinity of the device and may influence the measurement. For measurements carried out during battery operation, care should be taken to ensure that possible electrostatic fields, which may occur during handling (carrying, depositing etc.) of the housing, are discharged before the measurement is performed.

Does humidity affect the concentration of air ions?

Yes, humidity affects the concentration of air ions. However, our ionometers measure the actual ion concentration which reaches the electrodes, meaning this influence can be disregarded.

When using the optional extension tube, should a reduction in the measured values be expected?

Yes, during the retention period of air ions within the intake transfer, recombination processes occur as a matter of course, which lead to a reduction in the air ion concentration.

End FAQ