To collect airborne fungal samples, first choose a method that fits your goal: impaction for quantitative work, Surface Air System for routine checks, and dust sampling to complement air data. Set up the sampler, confirm sterile media, leak-check, and calibrate flow rates. Sample defined volumes indoors and outdoors, log temperature, humidity, ventilation, and activity. Handle and preserve samples properly. Analyze via culture, microscopy, or DNA methods with blanks and duplicates. Report species, concentrations, metadata, and limitations—there’s more to master.
Choose the Appropriate Air Sampling Method
Before you collect samples, match the method to your goal, setting, and resources. Define your sampling criteria first. Note that media choice influences which fungi you detect; for example, SabCG performs well across common genera and is recommended as a standard medium. Additionally, understanding indoor air quality can help you prioritize which areas to sample most effectively.
For quantitative outbreak investigations or when you need high sensitivity for small spores, choose volumetric impaction (e.g., Andersen N-6); its method advantages include accuracy, reproducibility, and CFU/m³ outputs.
For fast routine monitoring in working environments, pick the Surface Air System; it’s simple and cost-effective, with consistent trends despite slightly lower counts than membrane filters.
When you need detailed contamination profiles in occupational studies, use membrane filter methods, accepting the labor-intensive processing.
For a quick qualitative overview with minimal gear, gravimetric settling plates work, but expect lower sensitivity and wind effects.
Consider dust sampling to complement air data and characterize longer-term indoor burden.
Set Up Equipment and Calibrate Flow Rates
Start by selecting a sampler compatible with your goal (impaction, filtration, or cyclone) and assembling it per the manufacturer’s instructions to prevent leaks.
During equipment assembly, secure the sampling head, tubing, and pump; verify sterile media are properly seated. Use glass Petri plates with Andersen impactors to minimize electrostatic losses.
Inspect seals and perform a quick leak check to confirm airtightness. Position the sampler at recommended height with clear airflow and stable support, away from vents and doors.
Next, perform flow calibration using a traceable rotameter or electronic calibrator. Adjust the pump to the manufacturer’s target rate (e.g., 20 L/min for a miniature cyclone). Always collect an outdoor control sample to establish a baseline for comparison.
Confirm each device’s flow because media resistance varies. Calibrate before and after use, document flow rates with timestamps, and guarantee reliable power.
Collect Air Samples and Record Environmental Data
Once your flow rates are confirmed, choose the sampling method that matches your objective and environment, then execute the run to a defined air volume or time.
Use impaction or filtration for culture-based CFU counts of viable fungi, spore traps for direct microscopy of total spores, and cyclone samplers when you’ll perform DNA analyses. The Global Spore Sampling Project routinely used cyclone samplers to collect airborne fungal DNA across worldwide sites. DNA-based detection methods can provide rapid results for species identification during your analysis.
For basic surveys, deploy passive plates for a fixed period. Plan sampling frequency, include baseline and post-activity points, and collect outdoor background controls.
Run replicates at each location; consider parallel culture and DNA methods. Record environmental factors at every interval: temperature, humidity, ventilation, airflow, occupancy, activity, room characteristics, moisture, and weather.
Document exact air volume per sample. Follow labeling, aseptic handling, and sample preservation to maintain integrity.
Process, Analyze, and Report Results
With samples collected and labeled with volumes and environmental notes, move straight into preparation and analysis. Air sampling methods include viable and non-viable approaches; using both can provide a comprehensive assessment.
Begin sample preparation by separating viable and non-viable workflows. Plate viable spores on selective media to enumerate CFU/m³ and identify colonies. For non-viable samples, mount filters or slides and perform microscopy for spores/m³ and morphology. If using molecular assays, extract DNA—direct addition, or improved lysis with Ballotini beads—then run species-specific PCR; nested PCR offers highest sensitivity.
Apply quality controls: process blanks to flag contamination and field duplicates to check reproducibility.
Proceed to data processing: clean datasets using controls, standardize units, and compare methods for consistency. Integrate temperature and humidity to assess seasonal or spatial patterns.
Report species, concentrations, metadata, uncertainties, method limitations, and QA results.