CEHN Articles of the Month, January 2015 Issue



Mold Occurring on the Air Cleaner High-Efficiency Particulate Air Filters Used in the Houses of Child Patients with Atopic Dermatitis.

Authors: Seong Hwan Kim, Guem Ran Ahn, Seung Yeol Son, Gwi-Nam Bae and Yeo Hong Hun




Fungi are known sources of irritation associated with atopic (allergic) diseases (asthma, allergic rhinoconjuctivitis, atopic eczema, and atopic dermatitis). Atopic dermatitis (AD) is an inflammatory, chronically relapsing and non-contagious itchy skin disease, and one of the most common allergic diseases in children. AD has been correlated with heredity factors, but in recent years the rapidly growing incidence of AD cannot be explained by genetic factors alone. Mechanisms for the development of AD involve interactions between the susceptible genes and the environment. The role of the indoor environment and particularly indoor air quality (IAQ) in the development of AD has been studied, and airborne biological contaminants, such as molds (types of fungi), have been identified as a major health issue. Mold sensitization develops in genetically predisposed individuals in response to recurrent or chronic environmental exposures. Many facilities use air cleaners to maintain good IAQ, but these cleaners are often contaminated with fungi, and can disperse spores into the indoor environment. Fungal contamination has been associated with high efficiency particulate air (HEPA) filters that are installed in many air cleaners. Recent increases in IAQ related issues inside atopic dermatitis-inflicted child patients houses (ADCPHs) has raised concerns, but prior to this study, information pertaining to the fungi of concern was not available in Korea.

This study was done to generate information in Korea about fungal contamination in ADCPHs, by quantitatively estimating the presence of fungi that are known sources of irritation associated with atopic diseases. To estimate the fungal contamination of ADCPHs, molds that were filtered by HEPA air cleaners were examined.

HEPA filters installed inside air cleaners of three different ADCPHs were tested. Air cleaners that had been in use for 6-12 months were sampled. The three ADCPH sites had indoor environmental conditions that were favorable to the growth of fungi. The three HEPA filters from the three ADCPH testing sites were coded as HEPA -A, -B, and -C, and were tested for the presence of mold. Fungal sampling was performed at nine sites in three divided sections (top, middle, and bottom), of each HEPA filter. The samples were then processed and incubated, then the number of colony forming units of the fungi were determined using a colony counter.

On HEPA filters -A, -B, and -C, the number of colony forming units (respectively) were estimated to be: 6.51 × 102 ± 1.50 × 102 CFU/cm2, 8.72 × 102 ± 1.69 × 102 CFU/cm2, and 9.71 ×102 ± 1.35 × 102 CFU/cm2. Several different fungal groups, including Aspergillus, Penicillium, Alternaria, Cladosporium, and Trichoderma were detected. The distribution of these fungal groups differed among the three HEPA filters. Cladosporium was the major fungal group found in filters -A and -C, and Penicillium was the major fungal group found in filter -B. Nine fungal species were identified, with Cladosporium cladosporioides being the most common among all three filters.

Several of the fungal species identified in the study are known to produce allergens that are common irritants in asthma patients, and exposure to their spores can provoke adverse health effects in susceptible individuals, including children with AD. The variance of the fungal distribution on the HEPA filters showed that distribution of fungi in the indoor air was different among the three testing sites. The authors also note that the fungi fil-tered in the HEPA filter were subject to wind stress, which can affect fungal survival rate. Thus, they suspect that a larger number of fungal species and/or spores would be present in the indoor environment than what is found on air cleaner filters. Overall, the study was able to identify allergenic fungal species present in the indoor environments of ADCPHs. The authors recommend that the assessment of air cleaner filters should be an alter-nate approach to understanding the IAQ of a house with AD patients, and that proper maintenance of the filters in ADCPHs is necessary. Further studies on the diversity of airborne fungi need to be conducted.


This study estimated the presence of certain airborne fungi of concern in 3 ADCPHs, and found several different fungal groups on each home’s air cleaner filters. Mold is a known irritant to susceptible individuals such as children with AD or asthma, and it is imperative that the environments within which children spend a lot of time (home, child care, and school) are kept as free from mold as possible. Public health programs at the state and local levels need adequate funding in order to educate families and the general public about mold hazards in the home. The U.S. Environmental Protection Agency (EPA) does not regulate mold or mold spores in indoor air. Thus, state or local child care licensing regulations should enforce IAQ standards to protect the health of young children within these facilities, and states should enforce IAQ standards within schools. The standards for both schools and child care facilities should include requirements for regular inspection for mold within the facilities, and, when necessary, testing and remediation.


Article found in Mycobiology