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Bangkok school indoor air quality: monitoring and intervention by positive pressure fresh air system
(2024-04-01)
Ongwandee, Maneerat
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Khianthongkul, Kiraphat
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Panyametheekul, Sirima
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Yongprapat, Kamomchai
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Srinaka, Kessara
A PM<inf>2.5</inf> crisis in Thailand has caused the Thai government and public to be increasingly concerned about children’s exposure to PM<inf>2.5</inf> during time in school. This study is a part of a project to create a modeled effective school indoor air quality management for the Bangkok Metropolitan Administration (BMA). We measured air quality and environment in 10 Bangkok school rooms, including CO<inf>2</inf>, CO, O<inf>3</inf>, PM<inf>2.5</inf>, PM<inf>10</inf>, TVOC<inf>PID</inf>, formaldehyde, airborne bacteria and fungi, and gaseous organic contaminants. The indoor-to-outdoor concentration ratios indicated that either outdoor sources or indoor + outdoor sources were the predominant contributors to PM in naturally ventilated classrooms. Meanwhile, PM levels in air-conditioned classrooms strongly depended on class activities. CO<inf>2</inf> measurements showed that the air-conditioned classrooms had a low 0.4 per hour air change rate and total fungal counts also reached 800 CFU m<sup>−3</sup>. Analysis of gaseous organic compounds showed that the two most abundant were aliphatic and aromatic hydrocarbons, accounting for 60% by mass concentration. Interestingly, 2‐ethyl‐1‐hexanol, a mucous membrane irritant, was detected in all study rooms. In one naturally ventilated classroom, we implemented a positive pressure fresh air system to mitigate in-class PM levels; it kept PM levels below 20 μg m<sup>−3</sup> throughout the class day. Students reported a 20–37% increase in satisfaction with the perceived indoor environmental quality and reported reduced rates in all symptoms of the sick building syndrome after implementing the positive pressure system.
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Volatile Organic Compounds from Unexpected Sources: Fabric Softener-Initiated Emissions
(2022-01-01)
Chatsuvan, Thabtim
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Homwuttiwong, Sahalaph
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Morris, John
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Ongwandee, Maneerat
A fabric softener is usually applied to laundry during a rinse stage. It is composed of surfactants, solvents and others, which can escape into the air and cause adverse effects. Emissions of volatile organic compounds (VOCs) from fabrics conditioned with liquid fabric softener were measured and compared with those unconditioned and conditioned with water. Undyed, naturally-and chemically-dyed silks, cotton, polyester, Tetron cotton (T/C) and rayon fabrics were tested. The test fabrics were cut into 15×40 mm rectangles and equilibrated for 24 hr at 30 °C in 20 ml vials. The emitted VOCs in the vial air were sampled, using a solid phase microextraction technique and then analyzed by a gas chromatograph-mass spectrometer. Alkanes and toluene were mostly detected from the unconditioned fabrics. Toluene was emitted from machine woven fabrics – cotton, polyester, T/C and rayon-but not detected in the hand-woven silk. The fabrics emitted total VOCs per unit projected surface area in the range of 1-9 µg/m2 as toluene equivalent. Water-washing reduced emissions by 4-55%, whereas the fabric softener treatment increased emissions by 10-163% from the water-treated ones, except for the undyed silk. The most commonly emitted VOCs, from the fabrics treated with the fabric softener, were ethyl 2-methyl butyrate, nonanal, d-limonene and eucalyptol – compounds used to enhance fragrance. This demonstrated that fabric softeners contribute to the release of several VOCs mixtures that did not originate from the fabric itself.
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Nicotine sorption to clothing treated with fabric softener
(2022-01-01)
Ongwandee, Maneerat
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Chatsuvan, Thabtim
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Morris, John
A fabric softener contains surfactants, solvents and other additives. When applied to laundry, these ingredients can coat fabric surfaces which may change sorption characteristics of the washed fabrics to indoor organic pollutants. We studied the changes by measuring the Fruendlich sorption isotherm parameters of undyed cotton, undyed silk, chemically-dyed (black) silk and polyester fabrics for two treatments: deionized water and commercial fabric softener (containing 8% diethyl ester dimethyl ammonium chloride). The isotherm test was performed by 2-L Tedlar bags filled up with 24-ppm gas-phase nicotine. Bags were shaken for 24 h at 25°C. Nicotine was collected by a solid phase microextraction (SPME) technique and then analysed with GC-FID. Cotton exhibited the highest sorption capacity for nicotine while polyester had the lowest for both treatments. Fabric softener application decreased the nicotine sorption of all fabrics by 1-3 orders of magnitude compared with those conditioned with water.
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Coal bottom ash use in traditional ceramic production: evaluation of engineering properties and indoor air pollution removal ability
(2020-11-01)
Ongwandee, Maneerat
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Namepol, Kan
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Yongprapat, Kamolchai
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Homwuttiwong, Sahalaph
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Pattiya, Adisak
Coal bottom ash (CBA) disposed to landfills causes environmental issues. Thus, we used CBA in traditional clay ceramics that had the triple advantage of consuming troublesome waste, adsorbing volatile organics and being decorative indoors, replacing up to 40% by weight of clay with CBA and firing from 700 to 1300 °C. Clay and CBA mixtures were cast, cured at room temperature for 24 h and fired at several temperatures. Firing temperature impacted linear shrinkage, water absorption and fracture toughness, more strongly than CBA mixing proportion. Above 1000 °C, fracture toughness and water absorption resistance was enhanced but shrinkage increased. However, adding CBA lessened the contraction. SEM confirmed complete sintering as clay particles fused as a rigid solid above 1000 °C. X-ray diffraction patterns of ceramics containing CBA showed crystobalite and labradorite, in addition to quartz, due to flux materials in CBA. Leachability tests showed that the CBA ceramics were not ‘toxic’ on the USEPA TCLP regulatory list. Adsorption of gaseous toluene, a representative indoor pollutant, followed a Freundlich model: CBA made the adsorption sites more homogeneous, reduced the interaction mechanisms on the surfaces and thus the Freundlich exponent. Increased CBA increased toluene adsorption by 2–7 times.
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Understanding interactions in the adsorption of gaseous organic compounds to indoor materials
(2017-02-01)
Ongwandee, Maneerat
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Chatsuvan, Thabtim
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Suksawas Na Ayudhya, Wichitsawat
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Morris, John
We studied adsorption of organic compounds to a wide range of indoor materials, including plastics, gypsum board, carpet, and many others, under various relative humidity conditions by applying a conceptual model of the free energy of interfacial interactions of both van der Waals and Lewis acid-base (e-donor/acceptor) types. Data used for the analyses were partitioning coefficients of adsorbates between surface and gas phase obtained from three sources: our sorption experiments and two other published studies. Target organic compounds included apolars, monopolars, and bipolars. We established correlations of partitioning coefficients of adsorbates for a considered surface with the corresponding hexadecane/air partitioning coefficients of the adsorbates which are used as representative of a van der Waals descriptor instead of vapor pressure. The logarithmic adsorption coefficients of the apolars and weak bases, e.g., aliphatics and aromatics, to indoor materials linearly correlates well with the logarithmic hexadecane/air partitioning coefficients regardless of the surface polarity. The surface polarity in terms of e-donor/acceptor interactions becomes important for adsorption of the strong bases and bipolars, e.g., amines, phenols, and alcohols, to unpainted gypsum board. Under dry or humid conditions, the adsorption to flat plastic materials still linearly correlates well with the van der Waals interactions of the adsorbates, but no correlations were observed for the adsorption to fleecy or plush materials, e.g., carpet. Adsorption of highly bipolar compounds, e.g., phenol and isopropanol, is strongly affected by humidity, attributed to Lewis acid-base interactions with modified surfaces.

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