Air & Surface Sampling Solutions for Detecting Mould Growth after a Flood

Threat of Mould Growth after a Flood and Torrential Rains

Mould is a common group of organisms which are found virtually anywhere, indoors and outdoors. Indoor mould growth is a larger health concern for occupants, especially for those with pre-existing health complications.

Mould most commonly grows in wet or moist areas which lack adequate ventilation and is a common occurrence after torrential rain and floods. With many parts of Australia's east coast such as Queensland and New South Wales enduring extreme weather conditions and flooding, the excess moisture, humidity and pooling of water have created the perfect breeding ground for the growth of mould. Keeping doors and windows closed during heavy downpours also restricts the amount of ventilation received to adequately reduce the amount of condensation that forms indoors. The microorganisms that turn into mould colonies are always present in the air which means mould growth can start within 24-48 hours of water exposure. (Staff, 2022)

Indoor mould growth if not correctly dealt with can lead to ongoing respiratory issues and symptoms of flu and fatigue. It is more harmful for people with an allergy towards mould, lung disease or people with chronic diseases such as diabetes, cancer, severe asthma, or low immunity.

There are many genera and species of mould with black mould being the most common indoor air quality concern. Mould associated with water damage often have mycotoxins, a naturally occurring toxic compound that poses a risk to human health. 

Mould Testing and Sampling for Mould Remediation

The AIOH (Australian Institute of Occupational Hygienists) states if any mould is sighted in a building it should be remediated immediately. If mould is suspected but not sighted, air sampling may be used to test for “hidden mould”. In the case of a mould infestation, professional mould assessors, indoor environmental professionals or certified occupational hygienists are employed to collect air and surface samples of the mould spores to analyse it in an accredited laboratory. Mould testing confirms the contamination, the concentration of mould infestation and the genera of mould present. The most common methods to collect a sample of mould spores include:

Air Sampling

Airborne mould can spread very easily. Air samples of mould spores can be used to gather data about mould present in a building. Air Sampling is a good source of background screening to ensure there isn’t a large source of mould in the building which is not identified. When taken in controlled conditions and properly analysed by a laboratory, air samples for mould are helpful in comparing relative particle levels between a problem and control area. There are several air sampling solutions used to collect air samples that can be analysed for mould such as:

• Optical Particle Counters- Optical particle counters such as the Nanozen DustCount 9000 have a built-in filter cassette for sample composition analysis. Real-time personal dust monitoring can help shave days and weeks off assessment and remediation efforts by providing instantaneous results. If the particle count is high (2 to 10-micron range), mould contamination is often present. Particle counts are taken inside, outside and in various zones and then compared.
• Spore Trap Cassettes – Spore Trap Cassettes such as the SKC VersaTrap Spore Trap Cassette traps smaller mould spores using higher flow air sampling pumps. It is an easy and inexpensive screening device that provides the sampling versatility you need to capture mould spores and other particles ranging from 1.5 to 3.9 µm. Spore Trap Cassettes are often used with a high-flow sampling pump such as the QuickTake 30 Sampling Pump. Spores impact onto a microscopic slide with a sticky surface and the slide is stained and analysed microscopically.

• Viable Cascade Impactor -A viable cascade impactor such as the BioStage Single-Stage Viable Bioaerosol Impactor meets NIOSH and ACGIH recommendations for sampling indoor and outdoor air for viable microorganisms. A high volume sampling pump such as the SKC  QuickTake 30  is used with the impactor at a sampling rate of at 28.3 L/min for a typical sample time of 2-5 minutes to collect an air sample. The impactor draws air through the sampler where multiple jets of air direct airborne particles toward the surface of the agar collection medium. The agar plates are then shipped to a microbiological laboratory for a growth and culture analysis.

Surface Sampling

Surface sampling is conducted to confirm the presence or absence of microbial growth on test surfaces. It can help determine if the microbial levels in the test areas are greater than the background levels. Surface sampling can also be used to determine if an area has been cleaned or remediated properly after mould contamination. Some common sampling media used to surface sample mould include:

• Microvacuum cassettes  - Carpeting can often be a reservoir of fungal spores To sample and collect fungal spores in irregular surfaces such as carpets, a vacuum-style cassette such as the SKC Microvacuum Cassettes for Surface Sampling is often used with a high-flow pump such as the QuickTake 30.  The SKC vacuum style cassette is available with a 0.45 um polycarbonate filter loaded into a 3-piece styrene cassette with 2-inch tubing nozzle.
• Sterile Swabs – Sterile Swabs such as the SKC Sterile Surface Swab Kit are ideal for determining the relative degree and type of biological contamination in an area. A swab or filter is wetted with sterile water or wash solution to wipe a specified area. The swab is then used to inoculate a culture plate.
• Lift Tape – Lift tape surface sampling is conducted by placing a clear sampling strip such as the Stick-to-it Lift Tape onto a surface and removing it with slow, steady force. The tape is then attached to glass slides and examined using light microscopy. 

Mould can grow anywhere where there is a prolonged period of dampness and high humidity. Proper remediation and removal of mould should be undertaken to prevent health hazards to occupants. Mould assessors use various techniques to identify the growth of mould and use sampling techniques to verify the extent of mould contamination and the type of mould. SKC offers a range of air and surface sampling solutions to collect airborne mould spores and visible surface mould spores. SKC is a leading brand trusted by occupational hygienists and industry professionals.

Contact your local Air-Met Scientific representative today to learn more about air and surface mould sampling solutions available for sale and rental at your local Air-Met Scientific office.