Current World Environment

Introduction

Problems with indoor air quality are important risk factors of human health in low-, middle and high-income countries.^1,2The concentrations of certain pollutants in indoor air may be 2 to 5 times and occasionally more than 100 times higher than those in outdoor air.^3,4An indoor environment has numerous emission sources, such as materials, temperature, humidity, ventilation, air exchange between outdoor and indoor environments, human activities,^{5, 6}topography, micro-environmental conditions and amount of dust in air⁷which may influence indoor pollution concentrations including biological contaminants.⁸Understanding and identifying the sources and relationships of biological contaminants with the environment are important because biological contaminants have been implicated in many diseases.²

Indoor air quality at places of worship may be of concern for sensitive or susceptible subgroups within certain populations because of their potential allergic effects. Mosques are partially or fully occupied for about 1 h for five intermittent periods during the day. Moreover, worshippers do not arrive or depart at the same time. Instead, they do so, on the basis of the time of congregation. Maximum occupancy is expected during the congregation of each prayer, which lasts about 20 min, and occupant density increases to more than 1.5 persons/m²．⁹Many existing mosques have installed air-conditioning split units (ACSU) to cool the air inside mosques with a high indoor temperature in tropical areas. However, the use of ACSUs may produce moisture that favours bacterial and fungal growth.¹⁰Khan and Karuppayil¹¹indicated that bacteria land fungal spores can be introduced into the air by anthropogenic means such as talking, sneezing, coughing, skin shedding, walking, ventilation ducts, carpets, soil and rice plants.^12,13

In Turkey and Saudi Arabia,^14,15inadequate ventilation rates and high CO₂, PM_2.5and biological pollutant concentrations are amongst the problems faced by mosque buildings. However, many researchers, for example, Nomanet al．,¹⁶focused only on thermal comfort and disregarded biological contaminants in mosques in Malaysia. Studying air and biological contaminants may help build mitigation strategies to decrease the negative effects of these contaminants, especially in crowded areas. Malaysia’s Industry Code of Practice (ICOP) recommended that the acceptable guideline limits for bacteria and fungi are 500 and 1000 cfu/m³,分别。¹⁷This study investigates the total bacterial counts, total fungal counts and PM₁₀concentration in the main prayer halls of mosques with different ventilation strategies. It also looked into the dominant types of bacterial and fungal within these significant parts of mosques.

Materials and Methods

Study Area

Biological contaminants sampling and particulate matter monitoring were performed in 25 mosques in Pulau Pinang, Malaysia. The distribution of the selected mosques is shown in Figure 1 of the 25 mosques, 17 were categorised as mosques with ACSUs, and 8 were grouped as mosques with non-ACSUs.

Figure 1:Location of ACSUs and non-ACSUs mosques around Pulau Pinang, Malaysia (map not to scale) Click here to view Figure

Collection of Samples and Analysis

Monitoring schedules duringZohor-AsarandFriday-Asarprayers are shown in Table 1．Anairborne particle counter (Lighthouse Handheld 3016 IAQ) used to measure the PM₁₀concentration wasplaced on a tripod,and monitoring was conducted at 1 m above the ground with 1 min intervals in the main prayer halls for 5 h to 5.5 h. Lighthouse Handheld 3016 IAQ was equipped with a laser diode light source and collection optics for particle detection.

Table 1: Monitoring schedule during Zohor-Asar and Friday-Asar prayers in the main prayer halls

Air samples were collected to measure the total count of both parameters in colony forming units per cubic metre of air and to identify the types of biological contaminants from the selected mosques. Bacteria and fungi were sampled under two conditions, namely, before and after the carpeted areas in the main prayer hall of the mosques were hoovered. The carpets were hoovered at an area of 9 m²(3 m × 3 m), and the samples were collected at 0.6 m above the ground level by using a microbial air sampler (100 Model Eco Pump, Merck,Darmstadt, Germany) with aflow rate of 100 l/min and a sampling time of 5 min. The bacteria and fungi were impacted in 20 ml of a nutrient plate containing tryptic soy agar and Sabouraud dextrose agar with chloramphenicol, respectively. The nutrient plates for bacteria and fungi were prepared in accordance with the sampler manufacturer’s recommendations by referring to the National Institute for Occupational Safety and Health (NIOSH) Method 0800 – Bioaerosol Sampling (Indoor Air).¹⁸The stage hole was sterilised with 70% ethanol solution when the collection dishes were changed to prevent cross-contamination. The agar dishes were then transferred to our laboratory. The bacterial and fungal specimens were incubated at 35 ± 1 °C for 24 h and 25 ± 1 °C for 5 days, respectively.¹⁹The collected samples were kept in a cool box and transferred to our laboratory. Colony forming units per cubic meter of air sampled (cfu/m³) are calculated as follows (Eq. 1).²⁰

Total bacterial or fungal counts (cfu/m³)．..(1)

Bacteria were partly identified using a Microgen GNA kit and Microgen ID software as extensively elaborated by Hussain etal．,²¹Gram-negative bacteria were determined via an oxidase test performed by using Microgen GNA+B kit (for oxidase positive) and Microgen GNA kit (for oxidase negative). The culture suspension was prepared by emulsifying a single colony from a 24h culture plate into 0.85% saline and mixed thoroughly. Biochemical test wells were inoculated with the suspension. The sample was then incubated aerobically at 35°C for 20–24h.

For Gram-positive cocci, catalase and coagulase tests were conducted using Microgen ID Staph for catalase positive and Gram-positive cocci in clusters. A culture suspension was prepared by emulsifying a single colony of the target bacteria from a 24 h culture plate to the suspension supplied in the kit, and the sample was mixed thoroughly. Biochemical test wells were inoculated with the suspension, and the samples were incubated aerobically for 20–24 h.

A catalase test was performed to identify Gram-positive rod bacteria. The isolated bacteria should be tested Gram-positive rods, catalase positive and spore positive. A culture suspension was prepared by emulsifying a single colony of the target bacteria from a 24 h culture plate in the suspension supplied in the kit, and the sample was mixed thoroughly. Then, the biochemical test wells were inoculated with the suspensions and incubated at 30 °C for 24 and 48 h. In all of the methods, the bacterial and fungal species were identified on the basis of their specific codes by using the Microgen ID software.

Results and Discussion

Table 2 shows the total bacterial and fungal counts in the main prayer halls in mosques with ACSUs and non-ACSUs. The total bacterial counts in mosques with ACSUs before and after carpet hoovering ranged from 166 cfu/m³to 660 cfu/m³and from 162 cfu/m³to 620 cfu/m³,分别。The total bacterial counts in mosques with non-ACSUs before and after carpet hoovering ranged from 67 cfu/m³to 502 cfu/m³and from 91 cfu/m³to 390 cfu/m³,分别。The results showed that the total bacterial counts in mosques with non-ACSUs after hoovering activities did not exceed the acceptable guideline limit by ICOP¹⁷(500 cfu/m³).

The total fungal counts in the mosques with ACSUs were 132 to 660 cfu/m³before carpet hoovering was performed. After carpet hoovering was conducted, the total fungal counts in the mosques were 118–658 cfu/m³．Meanwhile, the total fungal counts in mosques with non-ACSUs before and after carpet hoovering ranged from 50 to 576 cfu/m³and from 70 cfu/m³to 502 cfu/m³,分别。The results showed that the total fungal counts before and after hoovering activities in mosques with ACSUs and non-ACSUs did not exceed the acceptable guideline limit by ICOP¹⁷(1000 cfu/m³). GoÅ‚ofit-Szymczak²²suggested that air-conditioning systems should be efficiently and regularly maintained to ensure the proper hygienic quality of buildings and minimise biological contamination levels.

Table 2: Total bacterial counts and total fungal counts in the main prayer halls in mosques with ACSUs and non-ACSUs

Table 3 shows the mean PM₁₀concentrations in the main prayer halls in mosques with ACSUs and non-ACSUs. The mean PM₁₀concentrations in mosques with ACSUs (29.44 µg/m³) were higher than that in mosques with non-ACSUs (26.46 µg/m³). Mean PM₁₀浓度对ACSUs和non-ACSUs没有t exceed the acceptable guideline limit by ICOP¹⁷(150µg / m³). However, the mean PM₁₀concentrations in MQS12 in mosques with ACSUs were the highest and exceeded the acceptable guideline limit by ICOP¹⁷(150µg / m³) because of the mosque construction. Thus, the PM₁₀concentration in MQS12 was excluded in the average results. It is noteworthy to mention that airborne particulate matter is one of the major sources that can influence the bacteria and fungi growth.²³

Table 3: Mean PM₁₀concentrations in the main prayer halls in mosques with ACSUs and non-ACSUs

Fig. 2 and 3 respectively show the differences in the total bacterial and fungal counts on the samples incubated before and after hoovering activities in mosques with ACSUs and non-ACSUs. The results indicated that the percentage of the total bacterial counts in both mosques decreased by 64.71% and 75.00% after hoovering activities were performed, respectively. By comparison, the percentage of the total fungal counts in mosques with ACSUs increased by 64.71% after hoovering activities were accomplished. The percentage of the total fungal counts in mosques with non-ACSUs decreased by 87.50% after hoovering activities were completed.

Figure 2: Changes in total bacterial counts on samples incubated before and after hoovering activities in mosques with (a) ACSUs and (b) non-ACSUs Click here to view Figure

In some mosques, total bacterial and fungal counts do not decrease after hoovering activities because fine particles may not be trapped by the filter of a vacuum cleaner andmaybe resuspended in air, even though large particles are trapped by the airstream and deposited into the filter during hoovering.²⁴Consequently,bacteria and fungiwill be lifted into the air．In the present study, hoovering activities are inefficient in removing all bacteria and fungi on carpets. Durandet al．,²⁵found thatdustcollectedby using a vacuum cleaner is dependent on the type of carpet, humidity and characteristics of a house.Knibbset al．,²⁶stated that vacuum cleaner bags can also transmit considerable amounts of bioaerosols, especially airborne bacteria. Dust plays an important role in the aerosolisation and transportation of bacteria and may have important consequences associated with the spread of diseases.²⁷

Figure 3: Changes in total fungal counts on samples incubated before and after hoovering activities in mosques with (a) ACSUs and (b) non-ACSUs Click here to view Figure

A total of 10 types of bacteria and 13 types of fungi were identified in mosques with ACSUs (Figure 4) and non-ACSUs (Figure 5). The identified bacteria consisted ofStaphylococcusspp.,芽孢杆菌spp.,Micrococcispp., Gram-negative bacteria–1 type, Gram-negative bacteria,Candidaspp.(yeast),Streptococcusspp., Gram-negative bacteria–2 types, yeast andPseudomonasspp. Moreover, the highest percentage of bacterial in mosques with ACSUs and non-ACSUs (before and after hoovering) wereStaphylococcusspp.(100.00%) and芽孢杆菌spp.(100.00%). The lowest percentages of bacteria recorded in mosques with ACSUs before carpet hoovering were Gram-negative bacteria–2 types, yeast andPseudomonasspp. with 5.88%, whereas yeast was not detected after carpet hoovering was performed. In mosques with non-ACSUs, yeast,Streptococcusspp. andPseudomonasspp. were not detected before carpet hoovering. Similarly, Gram-negative bacteria–2 types, yeast andPseudomonasspp. were not observed after carpet hoovering. Few studies have been performed on airborne microorganisms in mosque buildings^{7, 15, 28, 29}in countries with a desert climate but not in countries in the tropics. These results showed that airborne bacteria are the main microbial contaminants. However,Pseudomonasbacteria have been found as the main emission sources from spray humidifiers.¹⁵

Figure 4: Bacterial types in mosques with ACSUs and non-ACSUs Click here to view Figure

The identified fungi in this study includedAspergillusspp.,A. niger,Moniliasithophila,Penicilliumspp.,Rhizopusspp.,Monilliellaacetoabutans,Mucorspp.,Trichodermaspp.,Cladosporiumspp.,Absidiaspp.,Sporotrichumspp.,Moniliaspp.andMoniliellaspp.The fungi with the highest percentages in mosques with ACSUs before and after carpet hoovering were dominated byAspergillusspp.(70.59%) andA．niger(82.35%), respectively. Some of the fungal types were not detected before (Moniliaspp.andMoniliellaspp.) and after (Sporotrichumspp.,Moniliaspp.andMoniliellaspp.) carpet hoovering.A．nigerwas the only fungus with the highest percentage in mosques with non-ACSUs before and after carpet hoovering, and their values were 100.00% and 87.50%, respectively. In mosques with non-ACSUs,Cladosporiumspp.,Absidiaspp.andMoniliellaspp.were not detected before carpet hoovering was conducted. After carpet hoovering was performed,Cladosporiumspp. andSporotrichumspp. were also not detected. Hameed and Habeeballah¹⁵found thatAspergillusspecies have the highest percentage and are the most common fungal types inside mosques.

Figure 5: Fungal types in mosques with ACSUs and non-ACSUs Click here to view Figure

Conclusions

In this study, 25 mosques with carpeted flooring were examined onZohororFridayandAsarprayer times in Pulau Pinang, Malaysia. The results demonstrated that the total bacterial counts, total fungal counts, and mean PM₁₀concentrations, were higher in mosques with ACSUs than in mosques without. Their concentrations (ACSUs) ranged from 166 cfu/m³to 660 cfu/m³118 cfu / m³to 660 cfu/m³and 11.15 ± 9.32 µg/m³to 49.30 ± 13.13 µg/m³_,respectively. The total bacterial counts slightly exceeded the acceptable guideline limit by ICOP, nevertheless, the total fungal counts and PM₁₀concentrations did not exceed the limit, possibly due to a higher volume of air circulating inside mosques with ACSUs.The moisture caused by the installation of ACSUs in mosques could be favourable to bacterial and fungal growth. Insome mosques, the total bacterial and fungal counts did not decrease after hoovering. These findings suggested that hoovering activities were not fully efficient in removing all biological contaminants from the carpet.The dominant types of bacteria found wereStaphylococcusspp.,芽孢杆菌spp. andMicrococcispp. On the other hand, dominant fungal species wasAspergillus niger．In conclusion, while carrying out hoovering activities, indoor air within acceptable quality should be maintained via suitable ventilation strategies in mosques, to protect worshippers from being exposed to health risks due to infections from bacterial and fungal uplifted from carpets.

Conflict of Interest

The authors declare that they have no known competing for financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This research was supported by the Ministry of Science Technology and Innovation Malaysia under SCIENCE FUND 1001/PAWAM/6013607 (06-01-05-SF0766) grant.

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