Commuter Exposures to VOCs in Boston,Massachusetts

This study examines the commuter’s exposure to six gasoline-related volatile organic compounds (VOCs): benzene, toluene, ethylbenzene, m-/p-xylene, o-xylene, and formaldehyde. The VOC concentrations to which commuters were exposed in four different commuting modes (driving, subway, walking, and biking) in Boston, Massachusetts, are compared. The VOC concentrations in participants’ homes and offices were also measured. Factors that could influence in-vehicle VOC concentrations, such as different traffic patterns, car model and vehicle ventilation conditions, were also evaluated. Driving a private car was associated with higher VOC concentrations and commuting on urban roadways resulted in the highest VOC concentrations. The use of car heaters resulted in higher in-vehicle VOC concentrations. The longer the subway commuters stayed underground, the higher their VOC exposures. The home-to-work car or subway commute represented about 10 to 20 percent of an individual’s total VOC exposure for these compounds.     

Student’s Exposure to Volatile Organic Compounds While Commuting by Motorcycle and Bus in Taipei City

This study examined student’s exposure to volatile organic compounds (VOCs) while commuting by bus and motorcycle in Taipei, Taiwan in the winter of 1992. A total of 19 target G5-C10 VOCs on three most frequently used commuting routes were collected on Tenax-GC adsorbent tubes. The VOCs were desorbed by thermal desorption method and analyzed by GCMS. The most abundant VOC exposure experienced by commuters was to toluene. Several alkylated benzenes, such as propyl benzenes, ethyl-methyl-benzenes and trimethyl-benzenes, were relatively abundant on the roads in Taipei. The mean benzene concentration measured in buses was 173 µg/m³ and 379.7 µg/m³ on motorcycles. On the average, the commuters in Taipei experienced about three to eight times higher VOC concentrations than the commuters in Los Angeles, California. Higher VOC concentrations were measured on motorcycles than in buses. The VOC concentrations were not significantly different between morning and afternoon commutes, nor among the three commuting routes. VOC concentrations measured in classrooms at three schools in downtown Taipei did not vary significantly on each sampling day. However, at each school the in-classroom VOC concentrations varied significantly over the six consecutive sampling days. The VOC concentrations measured on the roads were about five times higher than those measured in the school classrooms in the city. Moderate to high correlations were found among most of the measurements of the 19 VOCs. The survey questionnaire indicated that daily commuting time ranged from 45 minutes for elementary school students to 95 minutes for vocational school students. The projected upper-bound cancer risks associated with student’s exposure to benzene ranged from 7.5 x 10^-3 to 1.8 x 10^-5 during their commutes in Taipei.     

Carbon monoxide levels in popular passenger commuting modes traversing major commuting routes in Hong Kong

Vehicle exhaust is a major source of air pollution in metropolitan cities. Commuters are exposed to high traffic-related pollutant concentrations. Public transportation is the most popular commuting mode in Hong Kong and there are about 10.8 million passenger trips every day. Two-thirds of them are road commuters. An extensive survey was conducted to measure carbon monoxide in three popular passenger commuting modes, bus, minibus, and taxi, which served, respectively, 3.91 million, 1.76 million and 1.31 million passenger trips per day in 1998. Three types of commuting microenvironments were selected: urban–urban, urban–suburban and urban–rural. Results indicated that in-vehicle CO level increased in the following order: bus, minibus and taxi. The overall average in-vehicle CO level in air-conditioned bus, minibus and taxi were 1.8, 2.9 and 3.3 ppm, respectively. The average concentration level difference between air-conditioned buses (1.8 ppm) and non-air-conditioned buses (1.9 ppm) was insignificant. The fluctuation of in-vehicle CO level of non-air-conditioned vehicle followed the variation of out-vehicle CO concentration. Our result also showed that even in air-conditioned vehicles, the in-vehicle CO concentration was affected by the out-vehicle CO concentration although there exists a smoothing out effect. The in-vehicle CO level was the highest in urban–suburban commuting routes and was followed by urban–urban routes. The in-vehicle CO level in urban–rural routes was the lowest. The highest CO level was recorded after the vehicle traversed through tunnel. The average CO exposure of a commuter in tunnel can be 2–3 times higher than that at the other roads. The CO exposure level of public road transportation commuters in Hong Kong was lower than most other cities. Factors governing the CO levels were also discussed.     

Commuter exposure to volatile organic compounds under different driving conditions

The driving conditions that were tested for the in-vehicle concentrations of selected volatile organic compounds (VOCs) included transport modes, fuel distributions, vehicle ventilation conditions, driving routes, commute seasons, car models, and driving periods. This study involved two sampling seasons (winter and summer). The in-auto/in-bus/fixed site ratio of the wintertime mean concentrations was about 6/3/1 for total VOCs and 8/3/1 for benzene. On the median, the in-auto/in-bus exposure ratio ranged from 1.5 to 2.8 for the morning commutes, and ranged from 2.4 to 4.5 for evening commutes, depending on the target compounds. The wintertime in-auto concentrations were significantly higher (p<0.05), on the average 3–5 times higher, in a carbureted engine than in the three electronic fuel-injected cars. For the summertime in-auto concentrations of the target compounds except benzene, there were no significant differences between low and high ventilation conditions on the two urban routes. The urban in-auto benzene concentration was significantly higher (p<0.05) under the low ventilation condition. For the rural commutes, the in-auto concentrations of all target compounds were significantly higher (p<0.05) under the low ventilation condition. The in-auto VOC concentrations on the two urban routes did not differ significantly, and they were greater than the rural in-auto concentrations, with the differences being significant (p<0.05) for all target compounds. The summertime in-auto concentrations of benzene and toluene were greater than the wintertime in-auto concentrations, with the difference being significant (p<0.05), while the concentrations of the other target compounds were not significantly different between the two seasons. Neither car models nor driving periods influenced the in-auto VOC concentrations.     

Vehicle Occupants’ Exposure to Aromatic Volatile Organic Compounds While Commuting on an Urban-Suburban Route in Korea

Abstract

This study identified in-auto and in-bus exposures to six selected aromatic volatile organic compounds (VOCs) for commutes on an urban-suburban route in Korea. A bus-service route was selected to include three segments of Taegu and one suburban segment (Hayang) to satisfy the criteria specified for this study. This study indicates that motor vehicle exhaust and evaporative emissions are major sources of both auto and bus occupants' exposures to aromatic VOCs in both Taegu and Hayang. A nonparametric statistical test (Wilcoxon test) showed that in-auto benzene levels were significantly different from in-bus benzene levels for both urban-segment and suburban-segment commutes. The test also showed that the benzene-level difference between urban- segment and suburban-segment commutes was significant for both autos and buses. An F-test showed the same statistical results for the comparison of the summed in-vehicle concentration of the six target VOCs (benzene, toluene, ethylbenzene, and o,m,p-xylenes) as those for the comparison of the in-vehicle benzene concentration. On the other hand, the in-vehicle benzene level only and the sum were not significantly different among the three urban- segment commutes and between the morning and evening commutes. The in-auto VOC concentrations were intermediate between the results for the Los Angeles and Boston. The in-bus VOC concentrations were about one-tenth of the Taipei, Taiwan results.     

VOC source identification from personal and residential indoor,outdoor and workplace microenvironment samples in EXPOLIS-Helsinki,Finland

Principal component analyses (varimax rotation) were used to identify common sources of 30 target volatile organic compounds (VOCs) in residential outdoor, residential indoor and workplace microenvironment and personal 48-h exposure samples, as a component of the EXPOLIS-Helsinki study. Variability in VOC concentrations in residential outdoor microenvironments was dominated by compounds associated with long-range transport of pollutants, followed by traffic emissions, emissions from trees and product emissions. Variability in VOC concentrations in environmental tobacco smoke (ETS) free residential indoor environments was dominated by compounds associated with indoor cleaning products, followed by compounds associated with traffic emissions, long-range transport of pollutants and product emissions. Median indoor/outdoor ratios for compounds typically associated with traffic emissions and long-range transport of pollutants exceeded 1, in some cases quite considerably, indicating substantial indoor source contributions. Changes in the median indoor/outdoor ratios during different seasons reflected different seasonal ventilation patterns as increased ventilation led to dilution of those VOC compounds in the indoor environment that had indoor sources. Variability in workplace VOC concentrations was dominated by compounds associated with traffic emissions followed by product emissions, long-range transport and air fresheners. Variability in VOC concentrations in ETS free personal exposure samples was dominated by compounds associated with traffic emissions, followed by long-range transport, cleaning products and product emissions. VOC sources in personal exposure samples reflected the times spent in different microenvironments, and personal exposure samples were not adequately represented by any one microenvironment, demonstrating the need for personal exposure sampling.     

Vehicle Occupant Exposure to Carbon Monoxide

Abstract

This paper focuses on the auto commuting micro-environment and presents typical carbon monoxide (CO) concentrations to which auto commuters in central Riyadh, Saudi Arabia were exposed. Two test vehicles traveling over four main arterial roadways were monitored for inside and outside CO levels during eighty peak and off-peak hours extending over an eight month period. The relative importance of several variables which explained the variability in CO concentrations inside autos was also assessed. It was found that during peak hours auto commuters were exposed to mean CO levels that ranged from 30 to 40 ppm over trips that typically took between 25 to 40 minutes. The mean ratio of inside to outside CO levels was 0.84. Results of variance component analyses indicated that the most important variables affecting CO concentrations inside autos were, in addition to the smoking of vehicle occupants, traffic volume, vehicle speed, period of day and wind velocity. An increase in traffic volume from 1,000 to 5,000 vehicles per hour (vph) increased mean CO level exposure by 71 percent. An increase in vehicle speed from 14 to 55 km/h reduced mean CO exposure by 36 percent. The number of traffic interruptions had a moderate effect on mean concentrations of CO inside vehicles.     

Exposure to particulate matter in traffic: A comparison of cyclists and car passengers

Emerging evidence suggests that short episodes of high exposure to air pollution occur while commuting. These events can result in potentially adverse health effects. We present a quantification of the exposure of car passengers and cyclists to particulate matter (PM). We have simultaneously measured concentrations (PNC, PM2.5 and PM10) and ventilatory parameters (minute ventilation (VE), breathing frequency and tidal volume) in three Belgian locations (Brussels, Louvain-la-Neuve and Mol) for 55 persons (38 male and 17 female). Subjects were first driven by car and then cycled along identical routes in a pairwise design. Concentrations and lung deposition of PNC and PM mass were compared between biking trips and car trips.Mean bicycle/car ratios for PNC and PM are close to 1 and rarely significant. The size and magnitude of the differences in concentrations depend on the location which confirms similar inconsistencies reported in literature. On the other hand, the results from this study demonstrate that bicycle/car differences for inhaled quantities and lung deposited dose are large and consistent across locations. These differences are caused by increased VE in cyclists which significantly increases their exposure to traffic exhaust. The VE while riding a bicycle is 4.3 times higher compared to car passengers. This aspect has been ignored or severely underestimated in previous studies. Integrated health risk evaluations of transport modes or cycling policies should therefore use exposure estimates rather than concentrations.     

The effect of commuting microenvironment on commuter exposures to vehicular emission in Hong Kong

Vehicular exhaust emission has gradually become the major air pollution source in modern cities and traffic related exposure is found to contribute significantly to total human exposure level. A comprehensive survey was conducted from November 1995 to July 1996 in Hong Kong to assess the effect of traffic-induced air pollution inside different commuting microenvironments on commuter exposure. Microenvironmental monitoring is performed for six major public commuting modes (bus, light bus, MTR, railway, tram, ferry), plus private car and roadside pavement. Traffic-related pollutants, CO, NO_x, THC and O₃ were selected as the target pollutants. The results indicate that commuter exposure is highly influenced by the choice of commuting microenvironment. In general, the exposure level in decreasing order of measured pollutant level for respective commuting microenvironments are: private car, the group consisting light bus, bus, tram and pavement, MTR and train, and finally ferry. In private car, the CO level is several times higher than that in the other microenvironments with a trip averaged of 10.1 ppm and a maximum of 24.9 ppm. Factors such as the body position of the vehicle, intake point of the ventilation system, fuel used, ventilation, transport mode, road and driving conditions were used in the analysis. Inter-microenvironment, intra-microenvironment and temporal variation of CO concentrations were used as the major indicator. The low body position and low intake point of the ventilation system of the private car are believed to be the cause of higher intake of exhaust of other vehicles and thus result in high pollution level in this microenvironment. Compared with other metropolis around the world and the Hong Kong Air Quality Objectives (HKAQO), exposure levels of commuter to traffic-related air pollution in Hong Kong are relatively low for most pollutants measured. Only several cases of exceedence of HKAQO by NO₂ were recorded. The strong prevailing wind plus the channeling effect created by the harbor, the fuel used, the relative abundance of new cars and the successful implementation of the vehicle emission control program are factors that compensate the effect of the emission source strength and thus lead to low exposure levels.     

A mass transfer model for simulating VOC sorption on building materials

The sorption of volatile organic compounds (VOCs) by different building materials can significantly affect VOC concentrations in indoor environments. In this paper, a new model has been developed for simulating VOC sorption and desorption rates of homogeneous building materials with constant diffusion coefficients and material–air partition coefficients. The model analytically solves the VOC sorption rate at the material–air interface. It can be used as a “wall function” in combination with more complex gas-phase models that account for non-uniform mixing to predict sorption process. It can also be used in conjunction with broader indoor air quality studies to simulate VOC exposure in buildings.     

Characterizing relationships between personal exposures to VOCs and socioeconomic,demographic, behavioral variables

Socioeconomic and demographic factors have been found to significantly affect time-activity patterns in population cohorts that can subsequently influence personal exposures to air pollutants. This study investigates relationships between personal exposures to eight VOCs (benzene, toluene, ethylbenzene, o-xylene, m-,p-xylene, chloroform, 1,4-dichlorobenzene, and tetrachloroethene) and socioeconomic, demographic, time-activity pattern factors using data collected from the 1999–2000 National Health and Nutrition Examination Survey (NHANES) VOC study. Socio-demographic factors (such as race/ethnicity and family income) were generally found to significantly influence personal exposures to the three chlorinated compounds. This was mainly due to the associations paired by race/ethnicity and urban residence, race/ethnicity and use of air freshener in car, family income and use of dry-cleaner, which can in turn affect exposures to chloroform, 1,4-dichlorobenzene, and tetrachloroethene, respectively. For BTEX, the traffic-related compounds, housing characteristics (leaving home windows open and having an attached garage) and personal activities related to the uses of fuels or solvent-related products played more significant roles in influencing exposures. Significant differences in BTEX exposures were also commonly found in relation to gender, due to associated significant differences in time spent at work/school and outdoors. The coupling of Classification and Regression Tree (CART) and Bootstrap Aggregating (Bagging) techniques were used as effective tools for characterizing robust sets of significant VOC exposure factors presented above, which conventional statistical approaches could not accomplish. Identification of these significant VOC exposure factors can be used to generate hypotheses for future investigations about possible significant VOC exposure sources and pathways in the general U.S. population.     

Predicting the contents of BTEX and MTBE for the three types of tollbooth at a highway toll station via the direct and indirect approaches

This study was set out to assess the contents of five volatile organic compounds (VOCs), including BTEX (the acronym for benzene, toluene, ethylbenzene, and xylene) and methyl tertiary-butyl ether (MTBE), in three types of tollbooth (including the car lane/ticket-collecting, car lane/cash-collecting, and bus/truck lane tollbooths) at a highway toll station via the direct and indirect approaches. For the direct approach, VOC samples were collected from the breathing zone of booth attendants at all selected tollbooths during the three workshifts. For samples collected during the dayshift, we found VOC contents of BTEX and MTBE in both the car lane/ticket-collecting (=6.23, 21.93, 3.24, 8.56, and 5.63 ppb, respectively) and car lane/cash-collecting tollbooths (=5.98, 21.71, 3.25, 8.59, and 6.04 ppb, respectively) were quite comparable, but both were significantly higher than that in the bus/truck lane tollbooth (=3.13, 13.91, 2.05, 4.52, and 2.70 ppb, respectively). The same pattern can also be found for the other two workshifts. For the indirect approach, we conducted multivariate regression analyses to predict VOC contents for any given type of tollbooth by using the four independent variables of the vehicle flowrate, wind speed, relative humidity, and air temperature. We found that, except the vehicle flowrate, the other three factors did not have a significant effect on VOC contents in the three types of tollbooth. In addition, the magnitudes of the effect of the vehicle flowrate on VOC contents for the three types of tollbooth were: car lane/cash-collecting>bus/truck lane>car lane/ticket-collecting. All regression results yielded R²-values in the range of 0.41−0.74 indicating that the developed indirect approach was able to predict VOC contents for three types of tollbooth.     

Head-space, small-chamber and in-vehicle tests for volatile organic compounds (VOCs) emitted from air fresheners for the Korean market

The present study investigated the emission characteristics of gel-type air fresheners (AFs), using head-space, small-chamber, and in-vehicle tests. Five toxic or hazardous analytes were found in the headspace phase of AFs (toluene, benzene, ethyl benzene, and m,p-xylene) at a frequency of more than 50%. Limonene and linalool, which are known to be unsaturated ozone-reactive VOCs, were detected at a frequency of 58 and 35%, respectively. The empirical model fitted well with the time-series concentrations in the chamber, thereby suggesting that the empirical model was suitable for testing emissions. Limonene exhibited the highest emission rate, followed by m,p-xylene, toluene, ethyl benzene, and benzene. For most target VOCs, higher air change per hour (ACH) levels exhibited increased emission rates. In contrast, higher ACH levels resulted in lower chamber concentrations. The mean concentration of limonene was significantly higher in passenger cars with an AF than without. For other target compounds, there were no significant differences between the two conditions tested. Consequently, it was suggested that unlike limonene, the emission strength for aromatic compounds identified in the chamber tests was not strong enough to elevate in-vehicle levels.     

Emission of non-methane volatile organic compounds (VOCs) from boreal peatland microcosms—effects of ozone exposure

Non-methane volatile organic compounds (VOCs) emitted from boreal peatland microcosms were semiquantitatively determined using gas chromatography–mass spectrometry techniques in a growth chamber experiment. Furthermore, effects of vegetation composition and different ozone concentrations on these emissions were estimated by multivariate data analyses. The study concentrated on the less-studied VOCs, and isoprene was not analyzed. The analyses suggest that a sedge Eriophorum vaginatum is associated with emissions of the four most-emitted VOC groups (cyclic, aromatic, carbonyl and aliphatic hydrocarbon compounds) and also with VOCs emitted in smaller amounts (terpenoids and N-containing compounds). A woody dwarf shrub Andromeda polifolia was strongly associated with emissions of aromatic, carbonyl and terpenoid compounds. Results suggest that exposure to an ozone concentration of 150 ppb leads to an increased emission of most VOC groups. Emission of aromatic compounds seems to increase linearly with increasing ozone concentration. These observations indicate that peatlands may be a source of a vast range of volatile compounds to the atmosphere. For more accurate assessment of the impact of elevated tropospheric ozone on the terpenoid and non-terpenoid VOC emissions from peatlands, well-replicated open-air ozone-exposure experiments should be conducted.     

Personal exposure of graduate students attending the college of natural sciences or social sciences to volatile organic compounds on campus

The present study measured the levels of 24 selected volatile organic compounds (VOCs) in the personal air samples obtained from graduate students attending the college of natural sciences (GSNSs) or social science (GSSSs) during their daily activities on campus along with associated indoor and outdoor air samples. In addition, the sources of their personal exposure were characterized using multivariate statistical models. In the personal samples of GSNSs and GSSSs, 16 and 15 different VOCs were always detected, respectively. The personal exposure of five chlorinated hydrocarbons and six aromatics was significantly higher for GSNSs than for GSSSs. Consistently, the indoor levels of these compounds were higher for GSNSs (in research and laboratory rooms) than for GSSSs (in research rooms). However, the personal exposure of two aromatic VOCs (1,2,4- and 1,3,5-trimethylbenzene) was higher for GSSSs. Moreover, the personal exposure of the five chlorinated and six aromatic compounds was significantly correlated with VOC concentrations both in the research and laboratory rooms of GSNSs and with those in the research rooms of GSSSs. For certain VOCs, outdoor sources were also a major contributor to the personal exposure of both GSNSs and GSSSs. The multivariate models identified five factors that accounted for 81% of the total variance and four factors that explained 76% of the total variance. It was further suggested that multiple indoor sources in research rooms such as office equipment, building finishing materials, and air fresheners were the main source for the personal exposure to VOCs for GSNSs, whereas building finishing materials were the main source for GSSSs.     

Concentrations,properties, and health risk of PM2.5 in the Tianjin City subway system

A campaign was conducted to assess and compare the personal exposure in L3 of Tianjin subway, focusing on PM_2.5 levels, chemical compositions, morphology analysis, as well as the health risk of heavy metal in PM_2.5. The results indicated that the average concentration of the PM_2.5 was 151.43 μg/m³ inside the train of the subway during rush hours. PM_2.5 concentrations inside car under the ground are higher than those on the ground, and PM_2.5 concentrations on the platform are higher than those inside car. Regarding metal concentrations, the highest element in PM_2.5 samples was Fe; the level of which is 17.55 μg/m³. OC is a major component of PM_2.5 in Tianjin subway. Secondary organic carbon is the formation of gaseous organic pollutants in subway. SEM–EDX and TEM–EDX exhibit the presence of individual particle with a large metal content in the subway samples. For small Fe metal particles, iron oxide can be formed easily. With regard to their sources, Fe-containing particles are generated mainly from mechanical wear and friction processes at the rail–wheel–brake interfaces. The non-carcinogenic risk to metals Cr, Ni, Cu, Zn and Pb, and carcinogenic hazard of Cr and Ni were all below the acceptable level in L3 of Tianjin subway.

     

Volatile organic compounds (VOCs) in urban atmosphere of Hong Kong

The assessment of volatile organic compounds (VOCs) has become a major issue of air quality network monitoring in Hong Kong. This study is aimed to identify, quantify and characterize volatile organic compounds (VOCs) in different urban areas in Hong Kong. The spatial distribution, temporal variation as well as correlations of VOCs at five roadside sampling sites were discussed. Twelve VOCs were routinely detected in urban areas (Mong Kok, Kwai Chung, Yuen Long and Causeway Bay). The concentrations of VOCs ranged from undetectable to 1396 microg/m3. Among all of the VOC species, toluene has the highest concentration. Benzene, toluene, ethylbenzene and xylenes (BTEX) were the major constituents (more than 60% in composition of total VOC detected), mainly contributed from mobile sources. Similar to other Asian cities, the VOC levels measured in urban areas in Hong Kong were affected both by automobile exhaust and industrial emissions. High toluene to benzene ratios (average T/B ratio = 5) was also found in Hong Kong as in other Asian cities. In general, VOC concentrations in the winter were higher than those measured in the summer (winter to summer ratio > 1). As toluene and benzene were the major pollutants from vehicle exhausts, there is a necessity to tighten automobile emission standards in Hong Kong.     

VOC concentrations measured in personal samples and residential indoor,outdoor and workplace microenvironments in EXPOLIS-Helsinki,Finland

Thirty target volatile organic compounds (VOC) were analyzed in personal 48-h exposure samples and residential indoor, residential outdoor and workplace indoor microenvironment samples as a component of EXPOLIS-Helsinki, Finland. Geometric mean residential indoor concentrations were higher than geometric mean residential outdoor concentrations for all target compounds except hexane, which was detected in 40% of residential outdoor samples and 11% of residential indoor samples, respectively. Geometric mean residential indoor concentrations were significantly higher than personal exposure concentrations, which in turn were significantly higher than workplace concentrations for compounds that had strong residential indoor sources (d-limonene, alpha pinene, 3-carene, hexanal, 2-methyl-1-propanol and 1-butanol). 40% of participants in EXPOLIS-Helsinki reported personal exposure to environmental tobacco smoke (ETS). Participants in Helsinki that were exposed to ETS at any time during the 48-h sampling period had significantly higher personal exposures to benzene, toluene, styrene, m,p-xylene, o-xylene, ethylbenzene and trimethylbenzene. Geometric mean ETS-free workplace concentrations were higher than ETS-free personal exposure concentrations for styrene, hexane and cyclohexane. Geometric mean personal exposures of participants not exposed to ETS were approximately equivalent to time weighted ETS-free indoor and workplace concentrations, except for octanal and compounds associated with traffic, which showed higher geometric mean personal exposure concentrations than any microenvironment (o-xylene, ethylbenzene,benzene, undecane, nonane, decane, m,p-xylene, and trimethylbenzene). Considerable differences in personal exposure concentrations and residential levels of compounds with mainly indoor sources suggested differences in product types or the frequency of product use between Helsinki, Germany and the United States.     

Impacts of pavement types on in-vehicle noise and human health

Noise is a major source of pollution that can affect the human physiology and living environment. According to the World Health Organization (WHO), an exposure for longer than 24 hours to noise levels above 70 dB(A) may damage human hearing sensitivity, induce adverse health effects, and cause anxiety to residents nearby roadways. Pavement type with different roughness is one of the associated sources that may contribute to in-vehicle noise. Most previous studies have focused on the impact of pavement type on the surrounding acoustic environment of roadways, and given little attention to in-vehicle noise levels. This paper explores the impacts of different pavement types on in-vehicle noise levels and the associated adverse health effects. An old concrete pavement and a pavement with a thin asphalt overlay were chosen as the test beds. The in-vehicle noise caused by the asphalt and concrete pavements were measured, as well as the drivers’ corresponding heart rates and reported riding comfort. Results show that the overall in-vehicle sound levels are higher than 70 dB(A) even at midnight. The newly overlaid asphalt pavement reduced in-vehicle noise at a driving speed of 96.5 km/hr by approximately 6 dB(A). Further, on the concrete pavement with higher roughness, driver heart rates were significantly higher than on the asphalt pavement. Drivers reported feeling more comfortable when driving on asphalt than on concrete pavement. Further tests on more drivers with different demographic characteristics, along highways with complicated configurations, and an examination of more factors contributing to in-vehicle noise are recommended, in addition to measuring additional physical symptoms of both drivers and passengers.Implications: While there have been many previous noise-related studies, few have addressed in-vehicle noise. Most studies have focused on the noise that residents have complained about, such as neighborhood traffic noise. As yet, there have been no complaints by drivers that their own in-vehicle noise is too loud. Nevertheless, it is a fact that in-vehicle noise can also result in adverse health effects if it exceeds 85 dB(A). Results of this study show that in-vehicle noise was strongly associated with pavement type and roughness; also, driver heart rate patterns presented statistically significant differences on different types of pavement with different roughness.     

Comparison of the substrate effect on voc emissions from water based varnish and latex paint

BACKGROUND, AIMS AND SCOPE: The building materials are recognised to be major contributors to indoor air contamination by volatile organic compounds (VOCs). The improvement of the quality of the environment within buildings is a topic of increasing research and public interest. Legislation in preparation by the European Commission may induce, in the near future, European Union Member States to solicit the industries of paints, varnishes and flooring materials for taking measures, in order to reduce the VOC emissions resulting from the use of their products. Therefore, product characterisation and information about the influence of environmental parameters on the VOC emissions are fundamental for providing the basic scientific information required to allow architects, engineers, builders, and building owners to provide a healthy environment for building occupants. On the other hand, the producers of coating building materials require this information to introduce technological alterations, when necessary, in order to improve the ecological quality of their products, and to make them more competitive. Studies of VOC emissions from wet materials, like paints and varnishes, have usually been conducted after applying the material on inert substrates, due to its non-adsorption and non-porosity properties. However, in real indoor environments, these materials are applied on substrates of a different nature. One aim of this work was to study, for the first time, the VOC emissions from a latex paint applied on concrete. The influence of the substrate (uncoated cork parquet, eucalyptus parquet without finishing and pine parquet with finishing) on the emissions of VOC from a water-based varnish was also studied. For comparison purposes, polyester film (an inert substrate) was used for both wet materials. METHODS: The specific emission rates of the major VOCs were monitored for the first 72 h of material exposure in the atmosphere of a standardized test chamber. The air samples were collected on Tenax TA and analysed using thermal desorption online with gas chromatography provided with both mass selective detection and flame ionisation detection. A double exponential model was applied to the VOC concentrations as a function of time to facilitate the interpretation of the results. RESULTS AND DISCUSSION: The varnish, which was introduced in the test chamber 23 h after the application of the last layer of material, emitted mainly glycolethers. Only primary VOCs were emitted, but their concentrations varied markedly with the nature of the substrate. The higher VOC concentrations were observed for the parquets of cork and eucalyptus, which indicated that they have a much higher porosity and, therefore, a higher power of VOC adsorption than the finished pine parquet (and polyester film). The paint was introduced in the chamber just after its application. Only primary VOCs were emitted (esters, phthalates, glycolethers and white spirit) but some compounds, like 2-(2-butoxyethoxy)ethanol and diethylphthalate, were only observed for paint/polyester, which suggested that they were irreversibly adsorbed by the paint/concrete. Compared with the inert substrate, the rate of VOC emissions was lower for concrete in the wet-stage (first hours after the paint application) but slightly higher later (dry-stage) as a consequence of desorption. CONCLUSIONS: As to varnish, the substrates without finishing, like cork and eucalyptus parquets, displayed a higher power of adsorption of VOCs than the pine parquet with finishing, probably because they have a higher porosity. As concerns paint, the total masses of VOCs emitted were lower for concrete than for polyester, indicating that concrete reduces the global VOC emissions from the latex paint. Concrete is seen to have a strong power of adsorption of VOCs. Some compounds, namely 2-(2-butoxyethoxy)ethanol, diethylphthalate and TEXANOL (this partially), were either irreversibly adsorbed by the concrete or desorbed very slowly (at undetected levels). A similar behaviour had not been reported for gypsum board, a paint substrate studied before. RECOMMENDATIONS AND OUTLOOK: The present data suggest that concrete may be a recommendable substrate for paint in an indoor environment. As the nature of the substrate conditions the rate and nature of VOC emissions from wet materials, it must be explicit when emissions from composite materials are reported, in order to allow comparisons and labelling of the product in terms of indoor air quality.