Mold Contamination and Air Handling Units

Abstract

An investigation was conducted on selected locations in air handling units (AHUs) to (a) identify common mold species found on these locations, (b) determine whether some locations (and subsets) featured mold growth sites more frequently than others, (c) ascertain whether the operating condition of AHUs is related to mold contamination, and (d) provide a basis for a microbial sampling protocol for AHUs. A total of 566 tape lifts and 570 swab samples were collected from the blower wheel fan blades, insulation, cooling coil fins, and ductwork from 25 AHUs. All AHU conditions were numerically rated using a heating, ventilation and air-conditioning (HVAC) survey. Results showed that Cladosporium sp. fungi were commonly recovered in terms of growth sites and deposited spores, and they were found mainly in the blower wheel fan blades, the ductwork, and the cooling coil fins. Subsections of the fan blades, insulation, and cooling coil fins showed no preferred area for mold growth sites. Other organisms such as Penicillium sp., Aspergillus sp., and Paecilomyces sp. were recovered from the cooling coil fins and insulation. Because of the widespread prevalence of Cladosporium sp., there was no relationship between mold growth and operating condition. However, the presence of different species of molds in locations other than the blower wheel blades may indicate that the AHU condition is not optimal. A suggested microbial sampling protocol including interpretations of sample results is presented.

Clinical analysis of 76 patients pathologically diagnosed with pulmonary cryptococcosis

“…4) or office environment but also in automobiles, trains and other modern means of transportation. In particular, heating, ventilation and air-conditioning systems tend to foster fungal and bacterial contamination [23,24]. It has been reported that dust in the home environment also carries the potential for Cryptococcus contamination and subsequent exposure risk as high as 13% [21].…”

Influence of Indoor Microclimate Distribution on Mould Infestation in a University Library

“…In mechanically ventilated buildings, the system contributes on the contrary [15] most especially the Air Handling Units (AHU) which in its distribution of the conditioned air to the downstream possess potential to circulate mould spores throughout a structure thereby support mould growth. In addition, indoor hygrothermal fluctuations due to inadequate ventilation over a long periods of time results in faster deposition of spores on the material surfaces.…”

“…Previous studies exist on investigating the relationship between indoor mould exposure and health related issues [9][10][11][12] but no conclusive evidence exists [13,14]. This according to [15] is as a result of the difficulty in the determination of health risks due to mould exposure and that human responses are a function of a number of factors: types of moulds, the degree and length of exposure, previous history of exposure, and immune status.…”

Experimental Investigation of Ventilation Efficiency in a Dentistry Surgical Room

“…In health care buildings, ventilation systems are expected to preventing cross infection risks in addition to maintaining adequate thermal comfort to the patients, the caregivers and visitors. On the contrary, despite the high energy requirements [1,2], the HVAC contributes to making building unhealthy [3] as several cases of nosocomial or hospital acquired illness (HAI) had been previously reported [4][5][6]. These problems, amongst others, had hitherto led to the emergence of building performance diagnostics.…”