Airborne concentrations of bacteria and fungi in Thailand border market |
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Authors: | Pradub Reanprayoon Wattanachai Yoonaiwong |
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Institution: | (1) Department of Agriculture and Environment, Faculty of Science and Technology, Surindra Rajabhat University, Surin Province, 32000, Thailand |
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Abstract: | Thailand border market is where the local Thais, Cambodians, Laotians, and Burmeses exchange their goods and culture at the
border checkpoints. It is considered to be the source of aerial disease transmission especially for foreigners because it
is always very crowded with people from all walks of life. Unhealthy air quality makes this area high risk of spread of airborne
diseases. This study assessed airborne concentrations of bacteria and fungi in a border market to improve exposure estimates
and develop efficient control strategies to reduce health risk. The density and distribution of airborne bacteria and fungi
were investigated in the Chong Chom border market in Surin Province, Thailand. Eighteen air sampling sites were taken from
outdoors and various work environments including indoor footpaths, wooden handicraft shops, electronic shops, the secondhand
clothing shops, and fruit market areas. Exposed Petri plate method and liquid impinger sampler were used for sampling at the
breathing zone, 1.5 m above the floor level, during weekend and holiday. Meteorological factors such as relative humidity,
temperature, and light intensity were collected by portable data logger. The relative humidity was 67–73%, and temperature
29–33°C, and light varied between 18 and 270 Lux m−2. Gram-positive and Gram-negative bacteria were found at a mean value of 104 CFU m−3, and airborne fungi of 103 CFU m−3 were recorded. The highest concentration of culturable airborne microorganisms was found along the indoor footpath (9.62 × 104 CFU m−3 and 750.00 CFU/plate/h for impingement and sedimentation methods, respectively), the fruit market area (7.86 × 104 CFU m−3 and 592.42 CFU/plate/h for impingement and sedimentation methods, respectively), and the secondhand clothing shop (4.59 × 103 CFU m−3 and 335.42 CFU/plate/h for impingement and sedimentation methods, respectively) for Gram-positive bacteria, Gram-negative
bacteria, and fungi, respectively. The lowest concentration of Gram-positive bacteria, Gram-negative bacteria, and fungi was
found only at the outdoor area at 1.53 × 104 CFU m−3, 0.93 × 104 CFU m−3 and 0.80 × 103 CFU m−3 by means of impingement method and 136.67 CFU/plate/h, 69.25 CFU/plate/h, and 62.00 CFU/plate/h by means of sedimentation
methods for Gram-positive bacteria, Gram-negative bacteria, and fungi, respectively. The most frequently present airborne
bacteria were identified as Bacillus, Corynebacteria, Diplococcus, Micrococcus, Acinetobacter, Alcaligenes, Enterobacter, and spore former rods. Acremonium, Aspergillus, Cladosporium, Penicillium, and Sporotrichum were the most frequently found aerosol fungi genera. The distribution of airborne microorganisms correlated with relative
humidity and light factors based on principal component analysis. In conclusion, the border market is a potential source of
aerial disease transmission and a various hazards of bioaerosols for workers, consumers, sellers, and tourists. The bioaerosol
concentration exceeded the standard of occupational exposure limit. Many major indicators of allergenic and toxigenic airborne
bacteria and fungi, Acinetobacter, Enterobacter, Pseudomonas, Cladosporium, Alternaria, Aspergillus, and Penicillium, were found in the various market environments. |
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