Home environmental assessments should be regarded as valuable tools for the comprehensive management of asthmatic and allergic diseases. The prevalence rate of asthma and allergic rhinitis is very high in the United Arab Emirates (UAE) and the instance of asthma and allergic rhinitis is much higher in children than adults. The prevalence rate in children from UAE is as follows: 23% with allergic rhinitis, 14% with asthma, 10% with breathlessness or tightness in the chest and 9% with a nocturnal cough.1 Allergy or asthma is triggered by inhaling allergens such as dust, mites, pet dander, pollen, and mold. 2, 3

Indoor structures harbor allergens to make the home a primary target for the allergen. Fungi are one of the allergen which is prone to inhabit areas with high moist content and low light levels.2, 4 The purpose of this study is to evaluate the level and biodiversity of fungi in indoor environments and to find out the role of fungi in allergy and asthma.

What is a crawl space dehumidifier you ask? These are devices that intend to assist in the removal of any excess moistness and also get rid of high humidity levels from the air. High levels of humidity in your crawl spaces can be the main reason for a lot of unfriendly consequences in your house. Examples of such consequences are; heavy odors in your house, mold problems, allergy triggers, presence of pests, and structural damage.

Literature Review

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  • Flappen, C. Barnes, A. Frances, C. Dinakar, J. Portnoy. Home assessments for environmental triggers of asthma and allergens, 1977
  • P. Jones. Indoor air quality and health, 18 may 1999. Atmospheric environment 33 pg 4535 – 4564
  • RE Dales, D. Miller and E. Mcmullen. Indoor air quality and health: Validity and determinants of reported home dampness and molds, 1997. International Journal of Epidemiology, vol 26, No. 1
  • Deepake. Aero-microbiology studies of moisture affected buildings in the indoor environment, 2007. The Journal of Young investigators
  • Brian, H. Kimberly, W Dana, and K. George. Profile of Airborne fungi in buildings and outdoor environments in the United States. April 2002, Applied and Environmental Microbiology vol 68, No. 4, p 1743 -1753
  • JM Daisey, WJ Angell, MG Apte. Indoor Air Quality, ventilation and health symptoms in schools. An analysis of existing information.
  • RB Simmons, JA Noble, L Rose, D.L. Price, SA. Crow, AG Ahearn. Fungal colonization of automobile air conditioning system. August 1997 Journal of Industrial Microbiology and Biotechnology, vol 19 No.2
  • RB Simmons, JA Noble, L Rose, D.L. Price, SA. Crow, AG Ahearn. Fungal colonization of air filters from hospitals. Dec 1997, American Industrial Hygiene Association Journal. Vol 58 No. 12, Pg 900 -904.
  • -L. Pasanen, T. Juutinen, M.J. Jantunen, P. Kalliokoski. Occurrence and moisture requirements of microbial growth in building materials. 1992, International Biodeterioration & Biodegradation. Volume 30, Issue 4, Pages 273–283
  • Itisha Singh, Rajendra Kumar Singh Kushwahaand Pramila Parihar. Keratinophilic fungi in soil of potted plants of indoor environments in Kanpur, India, and their proteolytic ability. 2009, Mycoscience, Volume 50, Number 4, 303-307, DOI: 10.1007/s10267-009-0482-4


This study was conducted in ten indoor environments of Dubai, the United Arab Emirates during the summer season of July to August 2012 to assess the fungal presence.

Samples from air conditioner filter (A.C filter), carpet, indoor plant soil and pillow cover were collected by using sterile saline moistened swabs were rotated in 1cm square area through 1cm2 paper window hole and suspended in 3ml sterile saline. From this suspension, 10µl samples were inoculated into Sabouraud Gentamicin Chloramphenicol Agar (SGC) using a bacterial loop.

The dimensions of the filter and pillow cover were measured and total area was calculated using the formula l x b. The radius of the plant pot was measured and total surface area of the soil was calculated using the formulae π r 2.

Samples were transported into Dubai Falcon Hospital (Zabeel, Dubai, UAE) for processing. All culture plates were incubated at 37°C in a microbiology incubator (Shel lab, USA) and examined after 48 hours and the consecutive 24 hours up to 7 days at Dubai Falcon Hospital. All inoculation, slide preparation, and colony counting procedures were done in a microbiology safety cabinet (Faster, Italy).

The fungal colonies were counted and identified. The identification included cultural characteristics and morphology of hyphae and spores under microscopy using lacto phenol aniline blue.

Number of colonies was calculated for 1cm square area (number of colonies in 10µl x 3 x102) and total colony counts were calculated for the total area of the filter, pillow and superficial surface area of the soil. In the case of carpet, total colony count was calculated for1meter square area.

A questionnaire was prepared to assess any member of the residents were suffering from any type of allergy. The samples collected from those who suffer from allergy were included in Group 1 and from non-allergic were included in Group 2.


Table 1 shows fungi isolated from various indoor environments of people suffering from allergy (Group 1) and table 2 shows fungi isolated from various indoor environments of people without allergy (Group 2). Table 3 shows the comparison of fungal presence between the two groups. Figure 1 shows the distribution of fungi in group 1 and figure 2 shows the distribution of fungi in Group 2. Figure 3 shows the biodiversity of fungi in an indoor environment of both groups together. Figures 4, 5 and 6 show the cultural characteristics of fungi in SGCA. Figures 7 and 8 show the microscopic appearance of fungi including A. flavus and T. verrucosum which were isolated in this study.

Table1: Fungi isolated from the various indoor environment of people suffering from allergy (Group 1)

n = Number of samples *CFU – Colony Forming Unit MPN – Most Probable number

Table2: Fungi isolated from the various indoor environment of people without allergy (Group 2)

n = Number of samples *CFU – Colony Forming Unit MPN – Most Probable number

Table 3: Comparison of fungal presence in the indoor environment of people suffering from allergy (Group 1) and without allergy (Group 2)

*CFU – Colony Forming Unit MPN – Most Probable number Ab – Absent


The fungal isolates of this study include Aspergillus sp, Trichophyton sp and Alternaria sp. In a study done by Deepake in five indoor environments of Hydrabad shows similar results including Aspergillus sp, Curvilaria sp, Penicillium sp, Philophora sp, Helmithosporium sp and Yeast5. His study was carried on moist and damaged walls, but our study was on A. C. filters, carpets, plant soil and pillow cover. So the biodiversity of fungi varied due to climatic conditions such as temperature and humidity. In a study done by Brian in various indoor environments of USA had reported similar fungi6. Aspergillus sp were the most common fungi isolated from A.C filters of hospitals, schools, automobiles and residence.7, 8, 9 Trichophyton sp are commonly found in soil which is also isolated from the indoor plant soil.10

High incidence of fungi was seen in group 1 especially in plant soil and A. C filters. The fungi isolated from each plant soil pot surface was1.8 million to 4.5 million CFU. The incidence of fungi in group 1 was higher than Group 2 .The fungi isolated from the A. C filters of group 1 was 0.5 million to 2. 5 million CFU while in group 2, 0.4 million to 0.82 million CFU per unit of A. C filter. Indoor plants and carpets were absent in group 2 which reduced the incidence of fungi. Dampness and low light level enhance the growth of indoor fungi.11 The higher incidence of fungi in group 1 may be one of the reasons that leads to allergy or trigger the allergy in residents.


Aspergillus niger was isolated most commonly from A. C filters. Trichophyton species, A. fumigates and A. niger were the common fungi isolated from plant soil surface. Aspergillus species were also isolated from pillow cover and carpet. Thus, Aspergillus species were the most common fungi isolated from the indoor environment. High incidence of fungi was seen in the indoor environment of residents suffering from allergy.