Tassanee Prueksasit

Health Risk Assessment of Petrol Station Workers in the Inner City of Bangkok, Thailand, to the Exposure to BTEX and Carbonyl Compounds by Inhalation

ABSTRACT The occupational health risk of petrol station workers from exposure to BTEX and carbonyl compounds via inhalation was estimated in the inner city of Bangkok. Personal sampling was performed within the workers’ breathing zone using 2,4 dinitrophenylhydrazine cartridges and charcoal glass tubes connected to a personal air pump during eight working hours at six petrol stations. BTEX and carbonyl compounds were quantitatively analyzed by GC/FID and HPLC/UV, respectively. Of all detectable BTEX and carbonyl compounds, the levels of the four most prevalent compounds (benzene, ethylbenzene, formaldehyde, and acetaldehyde) were used to assess the lifetime cancer risk and 95% confidence interval of the risk levels were found to be totally higher than acceptable criteria for benzene (1.82 × 10–4–2.50 × 10–4), formaldehyde (7.81 × 10–6–1.04 × 10–5), ethylbenzene (4.11 × 10–6–5.52 × 10–6), and acetaldehyde (1.39 × 10–6–2.45 × 10–6). Thus, petrol station workers in the inner city of Bangkok have a potentially high cancer risk through inhalation exposure. With respect to the noncarcinogenic agents, toluene, m,p-xylene, o-xylene, and propionaldehyde, all non-cancer health risk were within hazard quotients of 1 and of acceptable risk.

Cancer risk analysis of benzene, formaldehyde and acetaldehyde on gasoline station workers

Background: Benzene, formaldehyde and acetaldehyde are carcinogenic substances to which gasoline station workers are most likely exposed via inhalation. To evaluate these compounds in the ambient air of gasoline stations, the inhalation exposure test on workers was performed and assessed. By the appropriate intervention of wearing mask and hand washing during work shift, we determined whether or not there is cancer risk to the exposure of benzene, formaldehyde and acetaldehyde using urinary biomarkers. Methods: A cross sectional study was conducted in 38 workers of 6 gasoline stations in Pathumwan District, Bangkok, Thailand. Inhalation and ambient air concentrations of benzene, formaldehyde and acetaldehyde were evaluated by GC/FID and HPLC/UV detectors. Urinary trans, trans-muconic acid (t,t-MA), formaldehyde and acetaldehyde concentrations detected in gasoline workers before and after appropriate intervention were analyzed by GC/FID. Results: The average inhalation exposure concentrations of benzene, formaldehyde and acetaldehyde were 195.56, 12.60 and 5.74 µg/m3, respectively. The level of benzene exposure was significantly higher than the ambient air level (independent t-test, p < 0.01). The average lifetime cancer risk of the workers exposed to benzene, formaldehyde and acetaldehyde was determined at the values of 2.15E-04, 1.27E-05 and 2.69E-06, respectively. Benzene and formaldehyde values were higher than an acceptable criteria defined as 1E-06. The amount of urinary t,t-MA, formaldehyde and acetaldehyde in the workers daily after 7-days appropriate intervention (wearing masks as personal protective equipment (PPE) and hand washing) was decreased. Formaldehyde and acetaldehyde, which were detected in urine, showed significantly lower than before intervention (pair t-test, p < 0.001). Conclusions: Results from our study confirmed that the gasoline workers have high chances of cancer risk from daily exposure to benzene and formaldehyde. The urinary’s t,t-MA, formaldehyde and acetaldehyde could be considerably used as biomarkers in gasoline station workers. An appropriate intervention, using PPE and hand washing, could reduce the cancer risk.

Health Risk of Exposure to Vehicular Emissions in Wind-Stagnant Street Canyons

In recent years, most stationary sources of air pollution have been removed from urban areas; however, mobile sources are currently the direct causes of air pollution–related health problems. In particular, in the complex configurations of city buildings, the wind becomes stagnant in street canyons, which leads to higher levels of air pollution inside these areas. In this chapter, the health risks due to exposure to vehicular emissions in street canyons are discussed using a case study of field measurement and risk assessment in the street canyons of Bangkok, Thailand. The pollutants of focus are polycyclic aromatic hydrocarbons (PAHs), one of the major hazardous air pollutants from vehicular emissions. Environmental standards have not been introduced in most of the countries, and information on PAH pollution is still lacking in Asian developing countries, where the population densities and levels of traffic pollution are reported to be very high, particularly in the large cities. This chapter also includes a literature review on PAHs. The Bangkok case study of field measurement and risk assessment was conducted for roadside residents who live in possible hot spots of traffic air pollution. The field measurements provide detailed information on PAH levels, such as the diurnal variations and seasonal variations in concentrations, taking influential factors of traffic and wind conditions into consideration. The results of the risk assessment suggested that Bangkok roadside residents in the street canyons are exposed to significant levels of health risk due to PAH exposure.

Relationship between PM10 and PM2.5 levels in high-traffic area determined using path analysis and linear regression

The objective of this study was to determine the relationship between PM10 and PM2.5 levels as related to meteorological conditions and traffic flow using both a linear regression analysis and a path analysis. The Particulate matter (PM) samples were collected from Sukhumvit road, Bangkok, Thailand, at both open (104 samples) and covered (92 samples) areas along the road. Fifteen percent of all samples were separated before the statistical models were run and used for model validation. The results from the path analysis were more elaborate than those from the linear regression, thus indicating that meteorological conditions had a direct effect on the particulate levels and that the effects of traffic flow were more variable in open areas. The model also indicated that meteorological conditions had an indirect effect and that traffic flow had a direct effect on particulate levels in covered areas. The model validation results indicated that for open areas, the R2 values were not very different between the path analysis and the linear regression model, but that the path analysis was more accurate than the linear regression model at very low PM concentrations. At high PM concentrations, the path analysis model also had a better fit than did the linear regression, so the predictions from the path analysis model were more accurate than those from the linear regression.

Cassava (Manihot Esculenta Crantz) Yields, Soil Nitrous Oxide Emission, and Soil Nitrogen Transformation Affected by Nitrification Inhibitors in Loamy Sand Soil in Thailand

The effects of nitrification inhibitors (NIs) on soil nitrous oxide (N2O) emission, soil ammonium (NH4+) and nitrate (NO3−), and cassava (Manihot esculenta Crantz) yields were investigated in a loamy sand soil in eastern Thailand. Treatments were chemical fertilizer (CF) and CF plus dicyandiamide (DCD) or neem (Azadirachta indica) oil at two rates of 5% and 10%. DCD had a greater reduction of soil N2O flux than the neem oil (P<0.10). DCD and neem oil retained NH4+-N in the soil by 79% and 63% (P ≤ 0.10), respectively. The NI effect on soil NO3−-N was small due to a low N fertilizer rate. The cassava root yield and N uptake were increased 4–11% and 2–18%, respectively, by use of NIs, but they were only significant for DCD (P ≤ 0.10). These findings suggest that NIs application may be a promising method for minimizing nitrogen loss and enhancing crop yields in a tropical cassava field.

Temporal Variation of Particle Size Distribution of Polycyclic Aromatic Hydrocarbons at Different Roadside Air Environments in Bangkok, Thailand

© 2012 Hoshiko et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Temporal Variation of Particle Size Distribution of Polycyclic Aromatic Hydrocarbons at Different Roadside Air Environments in Bangkok, Thailand