Determining factors for levels of volatile organic compounds measured in different microenvironments of a heavy traffic urban area (original) (raw)
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Roadside BTEX and other gaseous air pollutants in relation to emission sources
Atmospheric Environment, 2007
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.
Air Pollution and Health, 2018
Introduction: Traffic and mobile sources are possibly responsible to the most of the ambient volatile organic compounds (VOCs) in urban areas. This study aimed to measure and determine the traffic related concentrations of benzene, toluene, ethylbenzene, xylenes, formaldehyde, and acetaldehyde at the main streets of Tehran, Iran. Materials and methods: The samples were taken from highly populated streets or main roads with heavy traffic in Central, Northern, Eastern, Southern, and Western areas of Tehran. In total, 33 points for BTEX and 23 points for formaldehyde and acetaldehyde were selected for sampling. The sampling and analysis were performed according to NIOSH methods 1501 and 2016. Results: The averages (± SD) of benzene, toluene, ethylbenzene, xylenes, formaldehyde and acetaldehyde concentrations in Tehran were 15.04 (± 9.18), 23.42 (± 8.73), 4.97 (± 2.55), 11.81 (± 4.46), 107.11 (± 30.58) and 57.10 (± 18.28) ppbv, respectively. Benzene concentrations were 3.30 to 26.00 tim...
Pollution, 2019
This study was carried out to analyze the variations of Benzene, Toluene, and para-Xylene (BTp-X) present in the urban air of Delhi. These pollutants can enter into the human body through various pathways like inhalation, oral and dermal exposure posing adverse effects on human health. Keeping in view of the above facts, six different locations of Delhi were selected for the study during summer and winter seasons (2016-2017). The concentrations of BTp-X on online continuous monitoring system were analyzed by chromatographic separation in the gaseous phase followed by their detection using a Photo Ionization Detector (PID). The concentrations of BTp-X were found maximum at a high traffic intersection area as 68.35±48.26 µg/m 3 and 86.84±32.55 µg/m 3 in summer and winter seasons respectively and minimum at a residential area as 4.34±2.48 µg/m 3 and 15.42±9.8 µg/m 3 in summer and winter seasons respectively. The average BTp-X concentrations of summer and winter seasons were found as 9.88, 20.68, 28.52, 49.75, 64.04, and 77.59 µg/m 3 at residential, institutional, commercial, low traffic intersection, moderate traffic intersection and high traffic intersection areas respectively. Clearly, it has been found that the concentrations of these compounds were more on the traffic areas indicating that the vehicles are the major emission source. Hence, it may be concluded that the number of vehicles along with the high traffic congestion on the city streets and roads results in more accumulation of aromatic compounds and deteriorate the urban air quality.
TEMPORAL DISTRIBUTIONS OF VOLATILE ORGANIC COMPOUNDS ( VOCs ) IN AN EQUATORIAL URBAN ENVIRONMENT
2016
Volatile Organic Compounds (VOCs) are emitted mainly from motorized vehicles. They are considered to be carcinogenic. This research aimed to investigate the correlation between traffic flow and VOC trends and concurrently to examine the impacts of the weather parameters. The concentrations of VOCs were monitored at urban site (near Chowrasta Market) in Penang in Peninsular Malaysia in 2010 and 2015. Traffic volumes were recorded simultaneously. The monitoring of VOCs was performed using the Photo Ionization Detector (PID). The results showed that the mean concentration of VOCs during the morning rush hour was 436 ppb in 2010 and 631 ppb in 2015. The results of Pearson's correlation analysis showed a negative correlation (average r > -0.64) between VOCs concentration and temperature, while there was a positive correlation (average r > 0.78) with humidity. The traffic composition results show that more than 90 percent of the vehicles were cars and motorbikes. The United Stat...
Volatile organic compounds in 43 Chinese cities
Atmospheric Environment, 2005
Whole air samples were collected in 43 Chinese cities in January and February 2001, and methane and nonmethane hydrocarbon (NMHC) concentrations for those samples are here discussed. In order to identify the main sources of the hydrocarbons in these cities, cross-correlations with the general combustion tracer ethyne and the gasoline marker i-pentane were investigated. Most of the identified NMHCs correlated with ethyne or i-pentane suggesting that their primary source is combustion or gasoline evaporation. To differentiate between vehicular and other combustion sources, the benzene to toluene ratio characteristic of the Chinese vehicular fleet was calculated using roadside samples (collected in 25 cities). Cities where the main source of the NMHCs was traffic related were identified. The slope resulting from the correlation of selected gases was used to identify the likely sources of the NMHCs measured. Vehicular emissions were found to be an important source of isoprene in some cities. Different VOC mixing ratio distributions throughout the country were also investigated. This paper gives a general overview of urban VOCs in many Chinese cities. Future more rigorous studies will be necessary to further characterize VOC sources in China.
Spatial and temporal variation of BTEX in the urban atmosphere of Delhi, India
Benzene, toluene, ethylbenzene and xylene (BTEX) form an important group of aromatic Volatile Organic Compounds (VOCs) because of their role in the tropospheric chemistry and the risk posed by them to human health. Concentrations of BTEX were determined at different sampling points in the ambient air of Delhi in order to investigate their temporal and spatial distributions. Significant positive correlation coefficient (p b 0.01) was found between inter-species concentrations at all the sampling locations. Inter-species ratio and Pearson's correlations indicate that gasoline vehicular exhaust could be the major source of BTEX in Delhi. The inter-species ratios exhibit clear seasonal variations indicating differential reactivity of the VOC species in different seasons. Xylenes were found the largest contributor to the ozone formation followed by toluene.
Evaluation of Volatile Organic Compounds Levels inside Taxis Passing through Main Streets of Tehran
Air quality inside commuting vehicles has seldom been evaluated in Iran. Accordingly, this study investigates the levels of benzene, toluene, ethylbenzene and xylene (BTEX) during workdays characterized by heavy traffic inside taxis in Tehran-Iran between May 2009 and October 2010. The totals of 35 personal samples were collected onto solid sorbent tubes and the concentration of volatile organic compounds (VOCs) were analysed by gas chromatography technique equipped with flame ionization detector (GC/FID). The arithmetic means of personal monitoring of BTEX concentrations inside vehicles were found 72.77, 93.91, 9.90 and 4.23 ppb respectively. Exposures to BTEX during traffic flow in the evening were considerably higher than those measured in the morning. The weekdays BTEX level of inside vehicles illustrated significant differences among the studied months (p<0.05). The BTEX concentration ratios were estimated to be related to traffic emissions and similar for all the surveyed routes. In conclusion, the results confirmed that the emission of BTEX and their concentrations being highly associated with traffic jam as well as changes in meteorological conditions.
Atmospheric BTEX-concentrations in an area with intensive street traffic
Atmospheric Environment, 2009
The major threat to clean air in developed and industrializing countries is now posed by traffic emissions. The effects of traffic road modifications on the air quality are, however, rarely reported in the literature. The aim of this study was to determine the influence of the modernization and renovation of a traffic artery in the region of Mortsel (Antwerp, Belgium) on the concentration of volatile organic compounds such as: benzene, toluene, ethylbenzene and m-, p-, o-xylenes (BTEX). The original goal of the reconstruction works was to reduce the traffic lanes of one of the busiest streets in Antwerp, in order to discourage the road traffic and in consequence also to improve the air quality in this region. The average concentrations of BTEX before these works in 2003 were: 1.6, 7.0, 0.9, 2.3, and 0.9 mg/m 3 , for benzene, toluene, ethylbenzene, m þ p xylenes, and o-xylene, respectively. However, after the completion of the works, in 2005, they were slightly higher: 2.5, 9.5, 1.6, 3.4, and 1.3 mg/m 3 , respectively. The scatter plots of benzene against toluene, ethylbenzene and xylenes in 2003 and 2005 showed very good correlations. This fact indicated that all of the measured compounds originated from the same source, namely the road traffic. Moreover, the data obtained from an air-monitoring station at less than 6 km distance from the sampling site (operated by the Flemish Environment Agency, and located in Borgerhout, Antwerp), confirmed the lack of influence of background concentrations of BTEX. The obtained results led to the conclusion that the reduction of the number of traffic lanes had apparently increased the traffic jams and also increased the emission from cars. Therefore, these modernization works had even a negative impact on the local concentration of traffic-related pollutants as BTEX.
Volatile organic compounds in some urban locations in United States
Chemosphere, 2002
Importance of this paper: Air pollution in urban locations contains many components that originate from a wide range of industrial, motor vehicle, and natural emissions sources. Some of these components include compounds known or suspected to be carcinogenic, and some of them play important roles in atmospheric chemistry such as tropospheric ozone pollution and stratospheric ozone depletion. Therefore, it is essential to characterize the composition, magnitude, and the distribution of urban air pollution through extensive ambient air monitoring and assess the impact of these components on human health and global atmospheric chemistry.
International Journal of the Physical Sciences, 2012
The most universal atmospheric pollutants present in the atmosphere are one of the representatives of volatile organic compounds (VOCs), popularly known as benzene, toluene, ethylbenzene and xylene (BTEX) which have their origin from both natural and anthropogenic sources. These compounds make an important contribution in the formation of photochemical smog. In spite of the well known toxic effects of BTEX, data available on them in India is very limited and very less study have reported their levels in Indian metro-cities. This paper reviews the status of BTEX concentrations at different sampling points in the ambient air of Delhi in order to investigate their temporal and spatial distributions.