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Updated: Jul 15, 2026
12:02
Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA
Published on: May 2, 2018
Mold contamination and air handling units.
Stephen C Wilson1, Robert N Palmatier, Larysa A Andriychuk
1Center for Indoor Air Research, Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA.
Journal of Occupational and Environmental Hygiene
|May 10, 2007
Summary
Common indoor mold, Cladosporium sp., frequently contaminates air handling units (AHUs), particularly fan blades and ductwork. Mold presence in other areas may signal suboptimal AHU conditions, impacting indoor air quality.
Area of Science:
- Environmental microbiology
- Indoor air quality research
- Building science
Background:
- Air handling units (AHUs) are critical for indoor air quality (IAQ).
- Mold contamination in AHUs can impact occupant health and building systems.
- Understanding mold distribution and contributing factors is essential for effective management.
Purpose of the Study:
- To identify common mold species in AHUs.
- To determine mold prevalence across different AHU components.
- To assess the relationship between AHU operating conditions and mold contamination.
- To develop a microbial sampling protocol for AHUs.
Main Methods:
- Collected 566 tape lifts and 570 swab samples from 25 AHUs.
- Sampled blower wheel fan blades, insulation, cooling coil fins, and ductwork.
- Assessed AHU operating conditions using a standardized HVAC survey.
Main Results:
- Cladosporium sp. was the most common mold, found predominantly on fan blades, ductwork, and cooling coil fins.
- No specific preferred mold growth sites were identified within fan blades, insulation, or cooling coils.
- Penicillium sp., Aspergillus sp., and Paecilomyces sp. were also recovered from cooling coil fins and insulation.
- No correlation was found between AHU operating conditions and overall mold growth due to Cladosporium prevalence.
Conclusions:
- Cladosporium sp. is a common contaminant in AHUs, with specific locations showing higher prevalence.
- Mold in AHU components beyond fan blades may indicate suboptimal system conditions.
- The study provides a basis for a standardized microbial sampling protocol for AHUs.
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