Management of air quality in the vicinity of congested area in Kuwait

An assessment of air quality in the vicinity of a selected school has been carried out by monitoring the concentrations of primary pollutants. The results has shown that during the school hours, the measured pollutants emitted from the cars next to the selected school, such as CO and NO(2), are always under the allowable limits for Kuwaiti air quality standards. On the other hand, the concentrations of non methane hydrocarbon pollutant (nm-HC), some of which are considered to be cancergenic, are found to be above the Kuwaiti standard most of the times. A traffic counter is used to record the number of cars in the main road next to the school in 15 min intervals for 10 days during the monitoring period for air quality. Statistical analysis is performed to develop a relation for prediction of the necessary reduction in traffic, based on CO concentrations, during morning and afternoon periods on working days. A computer dispersion model (CALINE4) is also used to assess the CO concentrations based on recorded flow of traffic and emission inventory with the prevailing meteorological conditions existed at the specified time. After the validation of model, different scenarios have been evaluated to provide an acceptable solution to resolve the traffic congestion problem near the schools in the early morning hours with substantial reduction in pollution levels. The optimal solution for CO concentration reduction by managing smooth traffic flow is to reduce the traffic intensity by half in early morning and afternoon rush hours. The results of the predicted CO concentration in the vicinity of the school for the model and the statistical analysis has shown reduction of 30% and 42% respectively, for approximately 50% decrease in the car use. On the other hand the predicted CO concentration for the model and the statistics reached 24% and 33% respectively when 50% of students opted for buses instead of using private cars.     

Air pollution exposure monitoring and estimation. Part V. Traffic exposure in adults

In Oslo, traffic has been one of the dominating sources of air pollution in the last decade. In one part of the city where most traffic collects, two tunnels were built. A series of before and after studies was carried out in connection with the tunnels in use. Dispersion models were used as a basis for estimating exposure to nitrogen dioxide and particulate matter in two fractions. Exposure estimates were based on the results of the dispersion model providing estimates of outdoor pollutant concentrations on an hourly basis. The estimates represent concentrations in receptor points and in a square kilometre grid. The estimates were used to assess development of air pollution load in the area, compliance with air quality guidelines, and to provide a basis for quantifying exposure-effect relationships in epidemiological studies. After both tunnels were taken in use, the pollution levels in the study area were lower than when the traffic was on the surface (a drop from 50 to 40 micrograms m-3). Compliance with air quality guidelines and other prescribed values has improved, even if high exposures still exist. The most important residential areas are now much less exposed, while areas around tunnel openings can be in periods exposed to high pollutant concentrations. The daily pattern of exposure shows smaller differences between peak and minimum concentrations than prior to the traffic changes. Exposures at home (in the investigation area) were reduced most, while exposures in other locations than at home showed only a small decrease. Highest hourly exposures are encountered in traffic.     

Viable fungi and bacteria in personal exposure samples in relation to microenvironments

Personal exposures to viable fungi and bacteria were compared with the concentrations being assessed by stationary samplers in home and workplace microenvironments. A random sample of 81 elementary school teachers in eastern Finland performed two 24-hour measurement periods in wintertime. Concentrations and prevalences of viable fungi and bacteria on the collection filters were determined by cultivation method. The geometric mean concentration was 3-12 cfu m(-3) for total viable fungi, 0.6-3.7 cfu m(-3) for Penicillium and mainly under 1 cfu m(-3) for other fungi. The samples with higher fungal concentrations also had higher diversity of fungi than samples with lower concentrations. The total number of fungal genera recovered was 39 for personal, 34 for home and 23 for work samples. The variation in concentration of Penicillium explained even 25-95% of the variations of total fungal concentration in personal exposure, home and workplace environments. There was an association between personal exposure and home concentration of viable fungi and between personal exposure and home and work concentrations of viable bacteria. Personal exposure and home concentrations of fungi were higher in rural areas than in urban areas. Our results also indicate that presence of a certain fungus in a microenvironment does not necessarily mean similar findings in personal exposure samples.     

Overview of particulate exposures in the US trucking industry

As part of a large epidemiologic study of lung cancer, 55,000 subjects, we have conducted a nation-wide survey of particulate exposures in the US trucking industry. The goal is to differentiate the risks from various types of particulate exposures, such as traffic emissions and general air pollution. We hypothesize that exposures defined by job and work site characteristics can be linked with subjects using their personal job histories. This report covers exposures at 36 randomly chosen large truck freight terminals in the US. Measurements were made of PM2.5, elemental carbon (EC), and organic carbon (OC) upwind of the terminal (background) and in work areas, and by personal samples. Significant differences in exposure intensity, microg m(-3), were found for work locations and jobs relative to background levels (GM[GSD]) at terminal sites: PM2.5 9.8[2.34], EC 0.5[3.24], and OC 5.0[1.76]. Using EC as a marker for diesel particles, work locations varied significantly: office 0.3[3.7], dock area 0.7[2.89] and shop area 1.5[3.52]), as did job titles (non-smokers): clerk 0.1[9.98], dock worker 0.8[2.13], and mechanic 2.0[3.82]. Cigarette smoking contributed substantially to personal exposures, approximately doubling PM2.5 and OC, but having less of an effect on EC. Large differences were seen across the terminal sites due to differences in local regional air pollution levels from traffic and other sources. We conclude that it will be possible to estimate current exposures of the cohort using an exposure assignment matrix based on job title, work location, and terminal site. This distribution overlaps substantially with the general public's exposure to these sources.     

Non-invasive measurement of carbon monoxide burden in Guatemalan children and adults following wood-fired temazcal (sauna-bath) use

The use of wood-fired steam baths, or temazcales, is a potentially dangerous source of CO exposure in Guatemalan Highland communities where adults and children use them regularly for bathing, relaxation, and healing purposes. Physical characteristics of children predispose them to absorb CO faster than adults, placing them at greater exposure and health risks. Efforts to quantify temazcal exposures across all age groups, however, have been hampered by the limitations in exposure measurement methods. In this pilot study we measured COHb levels in children and adults following use of the temazcal using three field-based, non-invasive CO measurement methods: CO-oximetry, exhaled breath, and by estimation of COHb using micro-environmental concentrations and time diaries. We then performed a brief comparison of methods. Average CO concentrations measured during temazcal use were 661 ± 503 ppm, approximately 10 times the 15 min WHO guideline. Average COHb levels for all participants ranged from 12-14% (max of 30%, min 2%), depending on the method. COHb levels measured in children were not significantly different from adults despite the fact that they spent 66% less time exposed. COHb measured by CO-oximetry and exhaled breath had good agreement, but precision of the former was affected substantially by random instrument error. The version of the field CO-oximeter device used in this pilot could be useful in screening for acute CO exposure events in children but may lack the precision for monitoring the burden from less extreme, but more day-to-day CO exposures (e.g. indoor solid fuel use). In urban settings, health effects in children and adults have been associated with chronic exposure to ambient CO concentrations much lower than measured in this study. Future research should focus on reducing exposure from temazcales through culturally appropriate modifications to their design and practices, and targeted efforts to educate communities on the health risks they pose and actions they can take to reduce this risk.     

Do the pollution related to high-traffic roads in urbanised areas pose a significant threat to the local population?

Many large neighbourhoods are located near heavy-traffic roads; therefore, it is necessary to control the levels of air pollution near road exposure. The primary air pollutants emitted by motor vehicles are CO, NO₂ and PM. Various investigations identify key health outcomes to be consistently associated with NO₂ and CO. The objective of this study was the measurement-based assessment for determining whether by high-traffic roads, such as motorways and express ways, and the concentrations of CO and NO₂ are within normal limits and do not pose threat to the local population. Average daily values (arithmetic values calculated for 1-h values within 24 h or less, depending on result availability) were measured for concentrations of NO₂ and CO by automatic stations belonging to the Voivodship Environmental Protection Inspectorate in Katowice, in areas with similar dominant source of pollutant emission. The measurements were made in three sites: near the motorway and expressway, where the average daily traffic intensity is 100983 and 35414 of vehicles relatively. No evidence was found of exceeding average daily values equal to the maximum allowable NO₂ concentration due to the protection of human health in the measurement area of the stations. No daily average values exceeding the admissible CO concentration (8-h moving average) were noted in the examined period. The results clearly show lack of hazards for general population health in terms of increased concentrations of CO and NO₂ compounds that are closely related to high intensity car traffic found on selected motorways and speedways located near the city centres.     

A comparative study of respirable particulate microenvironmental concentrations and personal exposures

Personal monitoring (PM) for respirable suspended particulate matter (RSP) of thirty subjects was performed as part of an air pollution health effects study conducted in Houston, Texas. Parallel RSP measurements were performed in the study subjects' homes and two fixed site monitoring stations. The participants' daytime activities were independently recorded by study techicians. These data were used to characterize RSP concentrations in each microenvironment visited by the participants. Four estimates of daytime exposure to RSP were calculated based on two different microenvironmental models, and home and fixed site mean daytime RSP concentrations. These estimates were compared to mean daytime personal exposure from PM. Hourly estimates of exposure were calculated from a microenvironmental model and mean hourly home RSP concentrations and compared to hourly PM data. The results of the study indicate that, as in the case of NO₂, it is important to characterize indoor microenvironmental RSP concentrations according to location, sources, and concurrent activities, both qualitatively and quantitatively. Stratification of concentrations according to sources present and self-reported activity can lead to misclassification of exposures. For RSP and, probably, other pollutants with indoor sources and with short exposure integration times, adequate measures of exposure can only be obtained with very detailed and complex microenvironmental models or comprehensive personal monitoring.     

Indoor concentrations of carbon monoxide in selected urban microenvironments

CO concentrations were measured in five kindergartens, one children's hospital and two homes for aged, practically without indoor sources, all situated in the city centre, for ten random days in winter and ten in summer. The indoor CO concentrations were the result of the distance from and the traffic density in the nearest street, of general pollution level, seasonal differences, day-to-day variations and daily cycle of air pollution, the vicinity of traffic having a dominant influence. Therefore location of institutions for sensitive population groups in old city centres within a block of houses seems to be a suitable solution as far as exposure to CO is concerned.Revised version of a paper presented as poster at the VIth World Congress on Air Quality, Paris 1983.     

Ambient site, home outdoor and home indoor particulate concentrations as proxies of personal exposures

Despite strong longitudinal associations between particle personal exposures and ambient concentrations, previous studies have found considerable inter-personal variability in these associations. Factors contributing to this inter-personal variability are important to identify in order to improve our ability to assess particulate exposures for individuals. This paper examines whether ambient, home outdoor and home indoor particle concentrations can be used as proxies of corresponding personal exposures. We explore the strength of the associations between personal, home indoor, home outdoor and central outdoor monitoring site ("ambient site") concentrations of sulfate, fine particle mass (PM(2.5)) and elemental carbon (EC) by season and subject for 25 individuals living in the Boston, MA, USA area. Ambient sulfate concentrations accounted for approximately 70 to 80% of the variability in personal and indoor sulfate levels. Correlations between ambient and personal sulfate, however, varied by subject (0.1-1.0), with associations between personal and outdoor sulfate concentrations generally mirroring personal-ambient associations (median subject-specific correlations of 0.8 to 0.9). Ambient sulfate concentrations are good indicators of personal exposures for individuals living in the Boston area, even though their levels may differ from actual personal exposures. The strong associations for sulfate indicate that ambient concentrations and housing characteristics are the driving factors determining personal sulfate exposures. Ambient PM(2.5) and EC concentrations were more weakly associated with corresponding personal and indoor levels, as compared to sulfate. For EC and PM(2.5), local traffic, indoor sources and/or personal activities can significantly weaken associations with ambient concentrations. Infiltration was shown to impact the ability of ambient concentrations to reflect exposures with higher exposures to particles from ambient sources during summer. In contrast in the winter, lower infiltration can result in a greater contribution of indoor sources to PM(2.5) and EC exposures. Placing EC monitors closer to participants' homes may reduce exposure error in epidemiological studies of traffic-related particles, but this reduction in exposure error may be greater in winter than summer. It should be noted that approximately 20% of the EC data were below the field limit of detection, making it difficult to determine if the weaker associations with the central site for EC were merely a result of methodological limitations.     

Indoor air pollution levels in public buildings in Thailand and exposure assessment

Levels of pollutants including PM2.5 and PM2.5 composition (black carbon and water soluble ions), SO(2), NO(2), CO, CO(2), and BTEX (benzene, toluene, ethylbenzene, xylene) were monitored for indoor and outdoor air at a university campus and a shopping center, both located in the Northern suburb of Bangkok. Sampling was done during December 2005-February 2006 on both weekdays and weekends. At the university, indoor monitoring was done in two different air conditioned classrooms which shows the I/O ratios for all pollutants to be below 0.5-0.8 during the weekends. However, on weekdays the ratios for CO(2) and most detected BTEX were above 1.0. The concept of classroom occupancy was defined using a function of the student number in a lecture hour and the number of lecture hours per day. Classroom 2, which had a higher occupancy than classroom 1, was characterized by higher concentrations of most pollutants. PM2.5 was an exception and was higher in classroom 1 (37 microg/m(3), weekdays) as compared to classroom 2 (26 microg/m(3), weekdays) which was likely linked to the dust resuspension from the carpeted floor in the former. Monitoring was also done in the shopping mall at three different sites. Indoor pollutants levels and the I/O ratios at the shopping mall were higher than at the university. Levels of all pollutants measured at the car park, except for toluene and CO(2), were the highest. I/O ratios of the pollutants at the mall were above 1.0, which indicates the relatively higher influence of the indoor sources. However, the black carbon content in PM2.5 outdoor is higher than indoor, which suggest the important contribution from outdoor combustion sources such as the traffic. Major sources of outdoor air pollution in the areas were briefly discussed. Exposure modeling was applied using the time activity and measured pollutant concentrations to assess the exposure of different groups of people in the study areas. High exposure to PM2.5, especially for the people working in the mall, should be of health effect concern.     

Occupational and environmental aerosol exposure assessment: a scientific journey from the past, through the present and into the future

This paper reviews how aerosol exposure assessment, for people in both working and living environments, has evolved over the years. It charts the main scientific developments that led to progressively improved ways of thinking and methods to assess exposure to airborne particulate matter in a manner more relevant to human health. It has been a long scientific journey as one generation of pioneering contributors has handed off to the next. In the process a consistent rationale has emerged, producing aerosol sampling criteria--and in turn exposure standards--which have been increasingly relevant to actual human exposures. The journey continues as a new generation of scientists steps up to deal with the new challenges that are emerging. An appreciation of the history of what went before is essential to charting the most effective path looking forward.     

Exposure of motorcycle,car and bus commuters to carbon monoxide on a main road in the Tel Aviv metropolitan area,Israel

Short-term personal exposure of passengers in different types of motor vehicles to carbon monoxide was investigated in an intensively used main road in Israel’s Tel Aviv metropolitan area. According to monitoring stations of the Ministry for Environmental Protection (MEP), concentrations of carbon monoxide (CO) along the road, at a height of 3 m above pedestrian level, in the Tel Aviv metropolitan area, are currently very low. However, these measurements do not reflect the actual exposure of commuters, which were the main objective of this study. Four vehicle types/travel modes were investigated: private cars with closed windows, private cars with open windows, motorcycles, and buses. The commuter CO average exposure was the accumulative exposure divided by the duration of the sampling taken along the route, for each type of vehicles. The results showed that commuters in cars with closed windows were exposed to the highest mean CO level, 27.2 ppm, for a period of 38 min; those in a car with open windows, to 19.7 ppm for 38 min; motorcycle riders, to 12.8 ppm, for 17 min; and bus users were exposed to the lowest mean pollution level, of only 3.6 ppm, for 25 min. Thus, CO values of 1 to 3 ppm, as measured at an MEP adjacent monitoring station, may indicate the exposure to CO pollution of area residents, but do not represent the actual exposure of commuters on the congested main road.     

Health impact assessment of air pollution using a dynamic exposure profile: Implications for exposure and health impact estimates

In both ambient air pollution epidemiology and health impact assessment an accurate assessment of the population exposure is crucial. Although considerable advances have been made in assessing human exposure outdoors, the assessments often do not consider the impact of individual travel behavior on such exposures.Population-based exposures to NO₂ and O₃ using only home addresses were compared with models that integrate all time-activity patterns—including time in commute—for Flanders and Brussels. The exposure estimates were used to estimate the air pollution impact on years of life lost due to respiratory mortality.Health impact of NO₂ using an exposure that integrates time-activity information was on average 1.2% higher than when assuming that people are always at their home address. For ozone the overall estimated health impact was 0.8% lower. Local differences could be much larger, with estimates that differ up to 12% from the exposure using residential addresses only. Depending on age and gender, deviations from the population average were seen.Our results showed modest differences on a regional level. At the local level, however, time-activity patterns indicated larger differences in exposure and health impact estimates, mainly for people living in more rural areas. These results suggest that for local analyses the dynamic approach can contribute to an improved assessment of the health impact of various types of pollution and to the understanding of exposure differences between population groups.     

基于异质人群响应特征的交通噪声暴露评估研究

考虑异质人群不同声功能需求和时空分布,对异质人群交通噪声暴露特征进行评估。通过集记人口高斯分解和噪声预测,获取特征人群分布数据和交通噪声数据;基于特征人群年龄和声功能需求,标定各年龄段人群噪声响应函数并进行归一化处理,构建异质人群噪声响应曲线;构建交通噪声暴露评估模型,结合获取数据及噪声响应曲线进行噪声暴露评估。结果表明,3类声功能区中人群噪声暴露与年龄变量均呈现类抛物线趋势,40岁左右人群暴露影响较儿童和老人低59.9%左右。人均噪声暴露在夜间明显偏高,尤其在声功能需求较高的第1类声功能区,其人均噪声超标值比昼间高7 d B。特征人群的空间分布对噪声暴露影响显著,工作时段学校区域适学人群集中,其总噪声暴露风险为同等状况住宅区的1.2倍。综合考虑人群特征和时空分布等因素,可更科学地进行区域交通噪声污染评估。     

Personal exposures and microenvironmental concentrations of particles and bioaerosols

The aim of this study was to compare the personal exposure to particles and bioaerosols with that measured by stationary samplers in the main microenvironments, i.e., the home and the workplace. A random sample of 81 elementary school teachers was selected from the 823 teachers working for two councils in eastern Finland for the winter time measurement period. Bioaerosol and other particles were collected on filters by button samplers using personal sampling and microenvironmental measurements in homes and workplaces. The 24-hour sampling period was repeated twice for each teacher. Particle mass, absorption coefficient of the filter and the concentration of viable and total microorganisms were analyzed from each filter. In this paper, the study design, quality assurance principles and results of particle and bioaerosol exposure are described. The results show that particle mass concentrations, absorption coefficient and fungi were higher in personal exposure samples than in home and workplace samples. Furthermore, these concentrations were usually lower in the home than in the workplace. Bacterial concentrations were highest in heavily populated workplaces, while the viable fungi concentrations were lowest in workplaces. The fungi and bacteria results showed high variation, which emphasises the importance of quality assurance (duplicates and field blanks) in the microbial field measurements. Our results indicate that personal exposure measurements of bioaerosols in indoor environments are feasible and supplement the information obtained by stationary samplers.     

Comparison of exhaled carbon monoxide levels among commuters and roadside vendors in an urban and a suburban population in Pakistan

Carbon monoxide (CO) is one of the six criteria air pollutants related to urbanization and has a wide range of health effects. The study measured and compared the exhaled CO levels among commuters and roadside vendors in potentially heavy and low traffic volume areas of Karachi, a megacity in Pakistan. Saddar town [areas of M. A. Jinnah Road (Tibet Center, Denso Hall) and Empress Market] was selected to represent an area of high traffic volume and the suburban town of Gadap (Gadap and Gulshan-e-Maymar) was selected to represent an area of no or low traffic volume. The study compared the CO exposure of commuters and roadside vendors in high and low traffic volume in Karachi. CO exposure was measured in expired air using the breath analyzer module of Bacharach Monoxor-II, USA. A total of 326 individuals (115 commuters and 211 stationary roadside vendors) from Saddar town (n?=?193) and Gadap town (n?=?133) were selected. In addition, CO levels in ambient air in the same areas, using portable CO analyzer (Bacharach, Monoxor-II, USA), were measured. The mean ambient CO level at Saddar town was 15.6 (SE ± 2.6) ppm compared to 3.3 (SE ± 0.3) ppm at Gadap town. The mean CO level in expired air was significantly higher among nonsmokers at Saddar town (12.8 ± 0.5 ppm) compared to the nonsmokers at Gadap town (7.8 ± 0.4 ppm). The mean CO level in expired air among smokers was twice that of nonsmokers (21.6 vs. 10.6 ppm). CO in expired air was greater among high traffic volume commuters and roadside stationary population in Karachi, Pakistan. The population in Karachi is exposed to high concentration of air pollutants. These pollutants need to be characterized for health effects and interventions needs to be developed.     

南京市黄标车污染现状与管理对策

以南京市为例,依托机动车环保监管数据库,根据国家机动车排放模型CVEM计算出黄标车主要污染物一氧化碳、碳氢化合物、氮氧化物及颗粒物的年排放量,并系统回顾了近年来为控制黄标车污染所采取的区域限行、淘汰奖补和治理改造等针对性管理措施,分析了政策实施的进展及成效,进一步明确了黄标车治理的必要性。     

Monitoring genotoxicity among gasoline station attendants and traffic enforcers in the City of Manila using the micronucleus assay with exfoliated epithelial cells

Some types of occupations involve high levels of exposure to potentially genotoxic gaseous and particulate substances from internal combustion engines used in motor vehicles. These occupational exposures may contribute to the development of many illnesses, usually through chromosomal change mechanisms that include strand breakage, deletions, sister chromatid exchange and non-disjunction. To determine the effect of occupational exposure in gasoline station attendants and traffic enforcers, the micronucleus test was used. Exfoliated oral mucosa cells from 18 gasoline station attendants, 18 traffic enforcers and 18 control subjects in the City of Manila were examined for micronucleated cell (MNC) frequency. Analysis of buccal cells showed that MNC frequencies in exposed individuals were significantly greater than in control subjects (p < or = 0.05). However, between gasoline station attendants and traffic enforcers, MNC frequencies of the two exposed groups exhibited no significant difference. No relation was also found between MNC frequency and any of the factors such as age, smoking habits, alcohol habits and working period. This was further confirmed in the multiple regression analysis which showed that only occupational exposure was a good predictor of MNC frequency. The results of this study suggest that gasoline station attendants and traffic enforcers, compared to the control individuals, are at a greater risk of chromosomal damage. For the assessment of chromosomal damage, the study, development, and standardization of tests are recommended for public institutions concerned with matters regarding environmental quality and community health.     

Black carbon concentrations in a goods-movement neighborhood of Philadelphia,PA

Communities along the Delaware River in Philadelphia, USA such as Port Richmond, are subject to traffic associated with goods movement to and from port facilities and local industry. Air pollution associated with this traffic poses an environmental health concern in this and other urban areas. Our study measures black carbon (BC) in Port Richmond and examines its relationship to expected sources such as truck traffic. We used a participatory sampling method to conduct 1-min measurements over 8-hour periods at 14 homes, a school and park, during a 4-week period in June 2012. Measurements over 9 sampling days had a 30-min average BC concentration of 1.2 μg m^?3, and a maximum of 12 μg m^?3. Statistical analyses showed some effect of traffic, but greater association between BC concentrations and weather and time of day. BC concentrations varied more by location than by day, and distance to traffic arterials and interstate freeway was a predictor of this variance. While our dataset is limited by number and variety of observations, major findings indicate that BC concentration varies more by location than by day, there is a decrease in median BC concentration with increased distance from an interstate highway, and an expected effect of diesel traffic on average daily BC concentrations. Our findings are an important step towards understanding patterns and determinants of BC concentration in communities colocated with major ports. Our study also demonstrates that participatory methods in air pollution monitoring can help increase awareness of local air pollution levels.     

Monitoring and assessment of daily exposure of roadside workers to traffic noise levels in an Asian city: a case study of Bangkok streets

Four noise monitoring sites were strategically established to evaluate average noise level and audiometric assessment at various traffic zones of Bangkok Metropolitan Region (BMR). During the monitoring period, noise levels were found to be 72.8–83.0 dBA during day time and 59.5–74.5 dBA during night time. The finding also indicated that traffic noise levels depend on distance from roadside, diurnal variation and character of the traffic and street configuration. Audiometric measurement of 4000 persons was carried by four major hospitals in Bangkok to study the relationship between traffic noise exposure of groups of people working in the streets and hearing loss. Four different categories of occupational people, i.e., drivers, street vendors, traffic officers and dwellers were selected and were further classified into age groups (16–25, 26–35, 36–45 and 46–55 years old) to monitor the traffic noise induced hearing loss throughout their everyday lives. The control group was deliberately chosen to screen out the effects of traffic noise. According to the audiometric investigation, it was revealed that hearing capacity of the daily noise exposure groups living in the three urban sites (Yaowarat Road, Din Daeng Road and Ratchaprarop Road) were noticeably poorer than those who were living in suburban site (Phahonyothin Road). It was noted that the mean hearing threshold level (HTL) of the 16–25 years old groups were found to have better hearing capacity than those older adults of 46–55 years old. In particular the mean HTL dropped at the frequency of 4000 Hz. Among the occupational population who were living in the urban monitoring sites, the driver groups were found to have the highest risk of traffic noise induced hearing loss.