Health Risk Assessment of BTEXS Exposure in Photocopy Centers

AbstractPhotocopier is a machine generally used in most office. In making a copy, volatile organic compounds (VOCs) especially benzene, toluene, ethylbenzene, xylenes, and styrene (BTEXS) are released. Inhalation of these VOCs could cause health effects to the workers. The objective of this study was to determine the concentrations of BTEXS that the workers exposed in the working area and assess their health risks. The study had employed three different photocopy centers and monitored the concentrations of BTEXS obtained from the breathing zone of the workers. Samples were taken the first two weeks of the semester and throughout the semester. The results showed that the concentrations of BTEXS depended on the numbers of the photocopier, ventilation system and space in the photocopy centers. For all the centers, the highest concentrations of each compound found at the breathing zone of the workers were 2.26, 11.47, 1.52, 4.31 and 0.46 mg.m-3, respectively. The concentrations of BTEXS were used to determine the health risk. For non-cancer risk assessment, the HQ less than 88.84x10-4 indicated that no health effect could be caused by BTEXS. For cancer risk, only benzene was assessed and the result showed its risk of less than 0.5 per 1,000,000 people

Comparison of Direct-reading and Gravimetric Methods of Particle Measurement in a Science Building, Silpakorn University

This study aimed to develop relationships between particulate matter (PM) concentrations obtained from a direct-reading instrument to those from a gravimetric method. TSI DustTrak II Aerosol Monitors (Model 8530), a direct-reading instrument for PM10 and PM2.5 measurement, together with personal air pumps connected to a Sensidyne cyclone and a SKC Personal Environmental Monitor (PEM) for gravimetric PM10 and PM2.5 measurements respectively were deployed in the Faculty of Science building, Silpakorn University, Nakhon Pathom, Thailand. Comparison of the results from each instrument indicated that PM10 and PM2.5 concentrations obtained from the TSI DustTrak were higher. The linear relationship from ordinary least squares (OLS) regression between PM10 data determined by TSI DustTrak (x) and Sensidyne cyclone ( ) was significant (R2=0.92) and could be represented as  = 0.272x. For PM2.5, the relationship between concentrations determined by TSI DustTrak (x) and SKC PEM ( ) was also significant (R2=0.92) and represented by  = 4.848 . Validation of both equations was undertaken by comparing predicted values from these relationships against the actual concentrations found by gravimetric analysis, with R2=1.0 and 0.92 for PM10 and PM2.5, respectively. It is suggested that these site-specific OLS regression equations can provide fast and convenient estimation of concentrations derived by gravimetric analysis from direct-reading TSI DustTrak monitor data

Potential of pineapple waste extract (PWE) as co-substrate in anaerobic digestion of rice straw washwater (RSWW): enhancement of biogas production

This study aims to investigate the potential methane yield by mono-anaerobic digestion of rice straw washwater (RSWW) and pineapple waste extract (PWE) as well as the co-digestion of both RSWW and PWE at a ratio of 50:50 (v/v). The experiment was conducted at a controlled mesophilic temperature of 37 °C in Upflow Anaerobic Sludge Blanket (UASB) reactor for a period of approximately 55 days. The process performances were evaluated based on the efficiency of COD removal and methane production in relation to other parameters such as pH, organic loading rate (OLR) and alkalinity ratio. This study confirmed that the rate of COD removal for RSWW, PWE, and RSWW:PWE (50:50) were achieved the stable condition at 81, 89, and 86% respectively. The alkalinity ratio value and pH throughout the experimental period remained below 0.30 and kept in the range of 6.5–7.0 indicated the stable and good environment existed for anaerobic digestion within the UASB reactor. This study implies that the co-digestion of RSWW:PWE found to improve the efficiency of COD removal and production of methane during the mono-digestion of RSWW from 81 to 86% and 0.093 to 0.13 LCH4/g CODrem by the increment of 6.2 and 40%, respectively

Comparison of Direct-reading and Gravimetric Methods of Particle Measurement in a Science Building, Silpakorn University

This study aimed to develop relationships between particulate matter (PM) concentrations obtained from a direct-reading instrument to those from a gravimetric method. TSI DustTrak II Aerosol Monitors (Model 8530), a direct-reading instrument for PM10 and PM2.5 measurement, together with personal air pumps connected to a Sensidyne cyclone and a SKC Personal Environmental Monitor (PEM) for gravimetric PM10 and PM2.5 measurements respectively were deployed in the Faculty of Science building, Silpakorn University, Nakhon Pathom, Thailand. Comparison of the results from each instrument indicated that PM10 and PM2.5 concentrations obtained from the TSI DustTrak were higher. The linear relationship from ordinary least squares (OLS) regression between PM10 data determined by TSI DustTrak (x) and Sensidyne cyclone (y ̂) was significant (R2=0.92) and could be represented as y ̂ = 0.272x. For PM2.5, the relationship between concentrations determined by TSI DustTrak (x) and SKC PEM (y ̂) was also significant (R2=0.92) and represented by y ̂ = 4.848√x. Validation of both equations was undertaken by comparing predicted values from these relationships against the actual concentrations found by gravimetric analysis, with R2=1.0 and 0.92 for PM10 and PM2.5, respectively. It is suggested that these site-specific OLS regression equations can provide fast and convenient estimation of concentrations derived by gravimetric analysis from direct-reading TSI DustTrak monitor data.</jats:p

Estimation of Effects of Air Pollution on the Corrosion of Historical Buildings in Bangkok

Historical buildings are recognized as the valuable cultural heritage of a nation. They may suffer material deterioration unavoidably because of exposure to air pollution. We used geographic information systems with dose-response functions (DRFs) to estimate the corrosion of copper and Portland limestone, and their risk of corrosion with regard to historical buildings in Bangkok, Thailand. The first step was to find a suitable spatial interpolation method considering the air pollution and meteorological measurement data for 2010-2019 from 26 monitoring stations in Bangkok and its neighborhoods. Applying multiple performance measures, the inverse distance weighting (IDW) method was found to be the most suitable. Predictions of the pollutant concentration in the spatial atmosphere showed that the concentration of all pollutants (SO2, NO2, O3, and PM10) tends to increase in 2028. Air pollution exposure time duration tends to be a key factor affecting the corrosion of material. The results of spatial corrosion estimations indicated that in 2010, the corrosion of copper and Portland limestone were at acceptable levels; however, the estimated corrosion levels for 2019 and 2028 are higher and beyond the acceptable levels. Moreover, both materials in the Rattanakosin historical area exceed their tolerable corrosion rates with considerably serious risks in 2028. The results can be further used to establish active measures to reduce the rate of corrosion of historical buildings in Bangkok.</jats:p

Characterization of particulate matter emission from open burning of rice straw

Emission from field burning of crop residue, a common practice in many parts of the world today, has potential effects on air quality, atmosphere and climate. This study provides a comprehensive size and compositional characterization of particulate matter (PM) emission from rice straw (RS) burning using both in situ experiments (11 spread field burning) and laboratory hood experiments (3 pile and 6 spread burning) that were conducted during 2003-2006 in Thailand. The carbon balance and emission ratio method was used to determine PM emission factors (EF) in the field experiments. The obtained EFs varied from field to hood experiments reflecting multiple factors affecting combustion and emission. In the hood experiments, EFs were found to be depending on the burning types (spread or pile), moisture content and the combustion efficiency. In addition, in the field experiments, burning rate and EF were also influenced by weather conditions, i.e. wind. Hood pile burning produced significantly higher EF (20+/-8 g kg(-1) RS) than hood spread burning (4.7+/-2.2 g kg(-1) RS). The majority of PM emitted from the field burning was PM(2.5) with EF of 5.1+/-0.7 g m(-2) or 8.3+/-2.7 g kg(-1) RS burned. The coarse PM fraction (PM(10-2.5)) was mainly generated by fire attention activities and was relatively small, hence the resulting EF of PM(10) (9.4+/-3.5 g kg(-1) RS) was not significantly higher than PM(2.5). PM size distribution was measured across 8 size ranges (from 9.0 mum). The largest fractions of PM, EC and OC were associated with PM(1.1). The most significant components in PM(2.5) and PM(10) include OC, water soluble ions and levoglucosan. Relative abundance of some methoxyphenols (e.g., acetylsyringone), PAHs (e.g., fluoranthene and pyrene), organochlorine pesticides and PCBs may also serve as additional signatures for the PM emission. Presence of these toxic compounds in PM of burning smoke increases the potential toxic effects of the emission. For illustration, estimation of the annual RS field burning in Thailand was made using the obtained in situ field burning EFs and preliminary burning activity dat