Kim Oanh NT - Academia.edu (original) (raw)

Papers by Kim Oanh NT

AGU Fall Meeting Abstracts, Dec 1, 2019

Science and Technology Development Journal, 2009

Long range transport of ozone and its precursors can significantly impact the air quality in down... more Long range transport of ozone and its precursors can significantly impact the air quality in downwind regions. The problem of regional transport of ozone has been studied for more than three decades in Europe and U.S but not yet in Southeast Asia. This study investigated the regional scale distribution of tropospheric ozone over the Continental South East Asia Region (CSEA) of Thailand, Burma, Cambodia, Lao and Vietnam. The Models-3 Community Multi-scale Air Quality (CMAQ modeling system, driven by the NCAR/Penn State Fifth-Generation Mesoscale Model (MM5), is used for the purpose. The model domain covers the longitude range from 91'E to 111°E and the latitude range from 5°N to 25°N. Two most recent ozone episodes of March 24-26, 2004 and January 2-4, 2005 were selected which represent the typical meteorological conditions for high ozone concentrations periods of a year. The episode analysis was made based on available data from 10 and 4 monitoring stations located in Bangkok of...

Resources, Conservation and Recycling, 1996

A study on toxicity discharges from three pulp and paper mills, two in Vietnam and one in Thailan... more A study on toxicity discharges from three pulp and paper mills, two in Vietnam and one in Thailand, was conducted using the Microtox method, a rapid toxicity test with the marine bioluminescent bacterium, Photobacterium phosphoreum, as the test organism. Based on ...

Journal of Environmental Assessment Policy and Management, 2008

The objectives of this study were to assess potential health and productivity benefits for the ye... more The objectives of this study were to assess potential health and productivity benefits for the year 2010 with five scenarios for reducing particulate matter (PM10 and PM2.5) air pollution in the cities of Osaka, Houston, Bangkok and Seoul. Assuming a uniform 10% decline in ambient PM levels, the preventible cases of: (1) premature mortality ranged from 35 in Houston to 379 in Seoul, (2) chronic bronchitis ranged from 95 in Houston to 1,631 in Seoul, (3) cardiovascular disease ranged from 68 in Houston to 818 in Seoul, (4) pneumonia ranged from 28 in Houston to 336 in Seoul, (5) asthma attacks ranged from 388 in Osaka to 96,876 in Seoul, and (6) acute bronchitis ranged from 186 in Houston to 2,973 in Seoul. The per million population central estimate of the purchasing power parity adjusted value of health and productivity benefits ranged from 25millioninBangkokto25 million in Bangkok to 25millioninBangkokto160 million in Osaka. There was a wide variability in measured PM10 levels across cities. Percentages of active moni...

Aerosol Science and Technology, 2009

In principle, mass concentrations of black carbon (BC) (M BC) can be estimated by the measurement... more In principle, mass concentrations of black carbon (BC) (M BC) can be estimated by the measurement of the light absorption coefficient of BC. Filter-based methods, which quantify the absorption coefficient (b abs) from the change in transmission through a filter loaded with particles, have been widely used to measure M BC. However, reliable determination of M BC has been very difficult because of the large variability in the mass absorption cross section (C abs), which is the conversion factor from b abs to M BC. Coating of BC by volatile compounds and the coexistence of light-scattering particles contribute to the variability of C abs. In order to overcome this

Songklanakarin Journal of Science and …

Southeast Asia haze with elevated particulate matter (PM 10) often blankets Southern Thailand dur... more Southeast Asia haze with elevated particulate matter (PM 10) often blankets Southern Thailand during June-August period. During the haze period of August 2005, the highest 24h PM 10 concentration was 92 µg/m 3 in Songkhla and 108 µg/m 3 in Phuket. Though the levels were still below the 24h PM 10 National Ambient Air Quality Standard of 120 µg/m 3 , they were considerably higher than the annual average levels of 32 µg/m 3 in Songkhla and 56 µg/m 3 in Phuket. The variation in daily PM 10 levels during this period was largely dependent on the prevailing wind directions and the intensity of fire, expressed as the number of hotspots on NOAA satellite images, at the upwind regions. The backward trajectories obtained by HYSPLIT4 model revealed that on the days when PM 10 peaked the air masses arriving at the cities passed over the intensive fire region in Sumatra Island. The peak PM 10 levels were observed in Phuket on 16 th and in Songkhla on 13 th August 2005, i.e. during the same period when a large number of hotspots were seen in Sumatra Island of Indonesia (10 th-16 th August 2005). The PM 10 level dropped when the wind changed direction from southwesterly to southeasterly hence the air mass trajectory did not pass the fire region. The transport time of air masses from the source region to Southern Thailand during this period was around 2-3 days.

The global atmosphere is at a critical stage, particularly in relation to climate change. There i... more The global atmosphere is at a critical stage, particularly in relation to climate change. There is considerable scientific evidence of the causes and solutions that could protect human health and ecosystems, and effective action has resulted in the achievement of some internationally agreed goals. The phase-out of ozone depleting substances and lead in petrol by implementing relatively simple and cost-effective solutions demonstrates that, when most major stakeholders agree, significant progress is possible. Progress in achieving environmental goals for particulate matter (PM) and tropospheric ozone is mixed, despite the high levels of concern about their impacts, as solutions are complex and can be costly. Much of the developed world has successfully reduced concentrations of indoor and outdoor PM, sulphur and nitrogen compounds to levels close to or within World Health Organization guidelines. However, more remains to be done. Concern is high in Africa, Asia and Latin America, whe...

Asian J. Energy Environ, 2003

Abstract: The exhaust pipe of an diesel-powered, six-wheeled air conditioned bus was extended fro... more Abstract: The exhaust pipe of an diesel-powered, six-wheeled air conditioned bus was extended from the original level at 0.52 m height to the bus roof level, around 4 m. Effects of the extension on the street level of air pollutants (CO, HC, PM10) at the sitting breathing ...

Atmospheric Environment, 2007

Hourly concentrations of benzene, toluene, ethylbenzene, m,p-xylenes, and o-xylene (BTEX) plus CO... more Hourly concentrations of benzene, toluene, ethylbenzene, m,p-xylenes, and o-xylene (BTEX) plus CO, NO x , SO 2 were monitored at roadsides simultaneously with the traffic volume during the dry season of 2004, in Hanoi, Vietnam. The selected three streets included Truong Chinh (TC) with high traffic volume, Dien Bien Phu (DBP) with low traffic volume, and Nguyen Trai (NT) with high traffic volume running through an industrial estate. BTEX were sampled by SKC charcoal tubes and analyzed by GC-FID. Geometric means of hourly benzene, toluene, ethylbenzene, m,p-xylenes and o-xylene are, respectively, 65, 62, 15, 43, and 22 mg m À3 in TC street; 30, 38, 9, 26, and 13 mg m À3 in DBP street; and 123, 87, 24, 56, and 30 mg m À3 in NT street. Levels of other gaseous pollutants including CO, NO x , and SO 2 , measured by automatic instruments, were low and not exceeding the Vietnam national ambient air quality standards. BTEX levels were comparatively analyzed for different downwind distances (3-50 m) from the street, between peak hours and off-peak hours, as well as between weekdays and weekend. Results of principal component analysis suggest that the gaseous pollutants are associated with different vehicle types.

Journal of Environmental Assessment Policy and Management, 2008

Comparative analysis of maximum daily ozone levels in urban areas predicted by different statisti... more Comparative analysis of maximum daily ozone levels in urban areas predicted by different statistical models

Environmental …, 2009

A “piggyback” approach is used to characterize aerosol emissions to obtain input for large-scale ... more A “piggyback” approach is used to characterize aerosol emissions to obtain input for large-scale models of atmospheric transport. Particulate and gaseous emissions from diesel trucks, light-duty vehicles, and buses were measured by the Bangkok Pollution Control ...

Environmental Science & Technology, 2007

Atmospheric Environment, 2013

h i g h l i g h t s PM 2.5 and BTEX were measured at 2 sites across a congested road and free hig... more h i g h l i g h t s PM 2.5 and BTEX were measured at 2 sites across a congested road and free highway. Both roads had comparatively high roadside PM 2.5 during dry season. BTEX were higher in the urban congested road. SPSS confirmed multivariate relationships between pollution and traffic flows. On-route levels of PM 2.5 and BTEX were higher in the congested urban route.

Many large urban areas experience elevated concentrations of ground-level ozone pollution, which ... more Many large urban areas experience elevated concentrations of ground-level ozone pollution, which is reported to cause adverse effects on human health and the environment. The prediction of ground-level ozone is an important topic, which attracts attention from research communities and policy makers. This study investigates the potential of using the multi-layer perceptron (MLP) neural network technique to predict daily maximum ozone levels in the Bangkok urban area. The MLP was trained and validated using ambient air quality monitoring data and observed meteorological data for the high ozone months (January to April) in the area during a four year period, 2000-2003. The inputs to the MLP included the average concentration of air pollutants (nitrogen oxide, nitrogen dioxide, and non-methane hydrocarbon) and meteorological variables (wind speed and direction, relative humidity, temperature, and solar radiation) during the morning rush hours. The MLP network, which contained 8 input layer neurons, two hidden layers (10 hidden neurons for the first hidden layer, 14 hidden neurons for the second hidden layer) and 1 output layer neuron, was found to give satisfactory predictions for both the training and validated data sets. The performance of the MLP was better than the multivariable linear regression model developed based on the same dataset. For the validated dataset, the MLP predicted the daily maximum 1-h ozone concentration in the study area with a mean absolute error of 10.3 ppb, a root mean square error of 13.5 ppb, a coefficient of determination (R 2) of 0.85, and an index of agreement of 0.89.

AGU Fall Meeting Abstracts, Dec 1, 2019

Science and Technology Development Journal, 2009

Long range transport of ozone and its precursors can significantly impact the air quality in down... more Long range transport of ozone and its precursors can significantly impact the air quality in downwind regions. The problem of regional transport of ozone has been studied for more than three decades in Europe and U.S but not yet in Southeast Asia. This study investigated the regional scale distribution of tropospheric ozone over the Continental South East Asia Region (CSEA) of Thailand, Burma, Cambodia, Lao and Vietnam. The Models-3 Community Multi-scale Air Quality (CMAQ modeling system, driven by the NCAR/Penn State Fifth-Generation Mesoscale Model (MM5), is used for the purpose. The model domain covers the longitude range from 91'E to 111°E and the latitude range from 5°N to 25°N. Two most recent ozone episodes of March 24-26, 2004 and January 2-4, 2005 were selected which represent the typical meteorological conditions for high ozone concentrations periods of a year. The episode analysis was made based on available data from 10 and 4 monitoring stations located in Bangkok of...

Resources, Conservation and Recycling, 1996

A study on toxicity discharges from three pulp and paper mills, two in Vietnam and one in Thailan... more A study on toxicity discharges from three pulp and paper mills, two in Vietnam and one in Thailand, was conducted using the Microtox method, a rapid toxicity test with the marine bioluminescent bacterium, Photobacterium phosphoreum, as the test organism. Based on ...

Journal of Environmental Assessment Policy and Management, 2008

The objectives of this study were to assess potential health and productivity benefits for the ye... more The objectives of this study were to assess potential health and productivity benefits for the year 2010 with five scenarios for reducing particulate matter (PM10 and PM2.5) air pollution in the cities of Osaka, Houston, Bangkok and Seoul. Assuming a uniform 10% decline in ambient PM levels, the preventible cases of: (1) premature mortality ranged from 35 in Houston to 379 in Seoul, (2) chronic bronchitis ranged from 95 in Houston to 1,631 in Seoul, (3) cardiovascular disease ranged from 68 in Houston to 818 in Seoul, (4) pneumonia ranged from 28 in Houston to 336 in Seoul, (5) asthma attacks ranged from 388 in Osaka to 96,876 in Seoul, and (6) acute bronchitis ranged from 186 in Houston to 2,973 in Seoul. The per million population central estimate of the purchasing power parity adjusted value of health and productivity benefits ranged from 25millioninBangkokto25 million in Bangkok to 25millioninBangkokto160 million in Osaka. There was a wide variability in measured PM10 levels across cities. Percentages of active moni...

Aerosol Science and Technology, 2009

In principle, mass concentrations of black carbon (BC) (M BC) can be estimated by the measurement... more In principle, mass concentrations of black carbon (BC) (M BC) can be estimated by the measurement of the light absorption coefficient of BC. Filter-based methods, which quantify the absorption coefficient (b abs) from the change in transmission through a filter loaded with particles, have been widely used to measure M BC. However, reliable determination of M BC has been very difficult because of the large variability in the mass absorption cross section (C abs), which is the conversion factor from b abs to M BC. Coating of BC by volatile compounds and the coexistence of light-scattering particles contribute to the variability of C abs. In order to overcome this

Songklanakarin Journal of Science and …

Southeast Asia haze with elevated particulate matter (PM 10) often blankets Southern Thailand dur... more Southeast Asia haze with elevated particulate matter (PM 10) often blankets Southern Thailand during June-August period. During the haze period of August 2005, the highest 24h PM 10 concentration was 92 µg/m 3 in Songkhla and 108 µg/m 3 in Phuket. Though the levels were still below the 24h PM 10 National Ambient Air Quality Standard of 120 µg/m 3 , they were considerably higher than the annual average levels of 32 µg/m 3 in Songkhla and 56 µg/m 3 in Phuket. The variation in daily PM 10 levels during this period was largely dependent on the prevailing wind directions and the intensity of fire, expressed as the number of hotspots on NOAA satellite images, at the upwind regions. The backward trajectories obtained by HYSPLIT4 model revealed that on the days when PM 10 peaked the air masses arriving at the cities passed over the intensive fire region in Sumatra Island. The peak PM 10 levels were observed in Phuket on 16 th and in Songkhla on 13 th August 2005, i.e. during the same period when a large number of hotspots were seen in Sumatra Island of Indonesia (10 th-16 th August 2005). The PM 10 level dropped when the wind changed direction from southwesterly to southeasterly hence the air mass trajectory did not pass the fire region. The transport time of air masses from the source region to Southern Thailand during this period was around 2-3 days.

The global atmosphere is at a critical stage, particularly in relation to climate change. There i... more The global atmosphere is at a critical stage, particularly in relation to climate change. There is considerable scientific evidence of the causes and solutions that could protect human health and ecosystems, and effective action has resulted in the achievement of some internationally agreed goals. The phase-out of ozone depleting substances and lead in petrol by implementing relatively simple and cost-effective solutions demonstrates that, when most major stakeholders agree, significant progress is possible. Progress in achieving environmental goals for particulate matter (PM) and tropospheric ozone is mixed, despite the high levels of concern about their impacts, as solutions are complex and can be costly. Much of the developed world has successfully reduced concentrations of indoor and outdoor PM, sulphur and nitrogen compounds to levels close to or within World Health Organization guidelines. However, more remains to be done. Concern is high in Africa, Asia and Latin America, whe...

Asian J. Energy Environ, 2003

Abstract: The exhaust pipe of an diesel-powered, six-wheeled air conditioned bus was extended fro... more Abstract: The exhaust pipe of an diesel-powered, six-wheeled air conditioned bus was extended from the original level at 0.52 m height to the bus roof level, around 4 m. Effects of the extension on the street level of air pollutants (CO, HC, PM10) at the sitting breathing ...

Atmospheric Environment, 2007

Hourly concentrations of benzene, toluene, ethylbenzene, m,p-xylenes, and o-xylene (BTEX) plus CO... more Hourly concentrations of benzene, toluene, ethylbenzene, m,p-xylenes, and o-xylene (BTEX) plus CO, NO x , SO 2 were monitored at roadsides simultaneously with the traffic volume during the dry season of 2004, in Hanoi, Vietnam. The selected three streets included Truong Chinh (TC) with high traffic volume, Dien Bien Phu (DBP) with low traffic volume, and Nguyen Trai (NT) with high traffic volume running through an industrial estate. BTEX were sampled by SKC charcoal tubes and analyzed by GC-FID. Geometric means of hourly benzene, toluene, ethylbenzene, m,p-xylenes and o-xylene are, respectively, 65, 62, 15, 43, and 22 mg m À3 in TC street; 30, 38, 9, 26, and 13 mg m À3 in DBP street; and 123, 87, 24, 56, and 30 mg m À3 in NT street. Levels of other gaseous pollutants including CO, NO x , and SO 2 , measured by automatic instruments, were low and not exceeding the Vietnam national ambient air quality standards. BTEX levels were comparatively analyzed for different downwind distances (3-50 m) from the street, between peak hours and off-peak hours, as well as between weekdays and weekend. Results of principal component analysis suggest that the gaseous pollutants are associated with different vehicle types.

Journal of Environmental Assessment Policy and Management, 2008

Comparative analysis of maximum daily ozone levels in urban areas predicted by different statisti... more Comparative analysis of maximum daily ozone levels in urban areas predicted by different statistical models

Environmental …, 2009

A “piggyback” approach is used to characterize aerosol emissions to obtain input for large-scale ... more A “piggyback” approach is used to characterize aerosol emissions to obtain input for large-scale models of atmospheric transport. Particulate and gaseous emissions from diesel trucks, light-duty vehicles, and buses were measured by the Bangkok Pollution Control ...

Environmental Science & Technology, 2007

Atmospheric Environment, 2013

h i g h l i g h t s PM 2.5 and BTEX were measured at 2 sites across a congested road and free hig... more h i g h l i g h t s PM 2.5 and BTEX were measured at 2 sites across a congested road and free highway. Both roads had comparatively high roadside PM 2.5 during dry season. BTEX were higher in the urban congested road. SPSS confirmed multivariate relationships between pollution and traffic flows. On-route levels of PM 2.5 and BTEX were higher in the congested urban route.

Many large urban areas experience elevated concentrations of ground-level ozone pollution, which ... more Many large urban areas experience elevated concentrations of ground-level ozone pollution, which is reported to cause adverse effects on human health and the environment. The prediction of ground-level ozone is an important topic, which attracts attention from research communities and policy makers. This study investigates the potential of using the multi-layer perceptron (MLP) neural network technique to predict daily maximum ozone levels in the Bangkok urban area. The MLP was trained and validated using ambient air quality monitoring data and observed meteorological data for the high ozone months (January to April) in the area during a four year period, 2000-2003. The inputs to the MLP included the average concentration of air pollutants (nitrogen oxide, nitrogen dioxide, and non-methane hydrocarbon) and meteorological variables (wind speed and direction, relative humidity, temperature, and solar radiation) during the morning rush hours. The MLP network, which contained 8 input layer neurons, two hidden layers (10 hidden neurons for the first hidden layer, 14 hidden neurons for the second hidden layer) and 1 output layer neuron, was found to give satisfactory predictions for both the training and validated data sets. The performance of the MLP was better than the multivariable linear regression model developed based on the same dataset. For the validated dataset, the MLP predicted the daily maximum 1-h ozone concentration in the study area with a mean absolute error of 10.3 ppb, a root mean square error of 13.5 ppb, a coefficient of determination (R 2) of 0.85, and an index of agreement of 0.89.