High Traffic Density Areas Research Articles

Residential Traffic Density and Childhood Leukemia Risk

Exposures to carcinogenic compounds from vehicle exhaust may increase childhood leukemia risk, and the timing of this exposure may be important. We examined the association between traffic density and childhood leukemia risk for three time periods: birth, time of diagnosis, and lifetime average, based on complete residential history in a case-control study. Cases were rapidly ascertained from participating hospitals in northern and central California between 1995 and 2002. Controls were selected from birth records, individually matched on age, sex, race, and Hispanic ethnicity. Traffic density was calculated by estimating total vehicle miles traveled per square mile within a 500-foot (152 meter) radius area around each address. We used conditional logistic regression analyses to account for matching factors and to adjust for household income. We included 310 cases of acute lymphocytic leukemias (ALL) and 396 controls in our analysis. The odds ratio for ALL and residential traffic density above the 75th percentile, compared with subjects with zero traffic density, was 1.17 [95% confidence interval (95% CI), 0.76-1.81] for residence at diagnosis and 1.11 (95% CI, 0.70-1.78) for the residence at birth. For average lifetime traffic density, the odds ratio was 1.24 (95% CI, 0.74-2.08) for the highest exposure category. Living in areas of high traffic density during any of the exposure time periods was not associated with increased risk of childhood ALL in this study.

Oxidative DNA damage and influence of genetic polymorphisms among urban and rural schoolchildren exposed to benzene

Traffic related urban air pollution is a major environmental health problem in many large cities. Children living in urban areas are exposed to benzene and other toxic pollutants simultaneously on a regular basis. Assessment of benzene exposure and oxidative DNA damage in schoolchildren in Bangkok compared with the rural schoolchildren was studied through the use of biomarkers. Benzene levels in ambient air at the roadside adjacent to Bangkok schools was 3.95-fold greater than that of rural school areas. Personal exposure to benzene in Bangkok schoolchildren was 3.04-fold higher than that in the rural schoolchildren. Blood benzene, urinary benzene and urinary muconic acid (MA) levels were significantly higher in the Bangkok schoolchildren. A significantly higher level of 8-hydroxy-2′-deoxyguanosine (8-OHdG) in leukocytes and in urine was found in Bangkok children than in the rural children. There was a significant correlation between individual benzene exposure level and blood benzene ( r s = 0.193, P < 0.05), urinary benzene ( r s = 0.298, P < 0.05), urinary MA ( r s = 0.348 , P < 0.01), and 8-OHdG in leukocyte ( r s = 0.130, P < 0.05). In addition, a significant correlation between urinary MA and 8-OHdG in leukocytes ( r s = 0.241, P < 0.05) was also found. Polymorphisms of various xenobiotic metabolizing genes responsible for susceptibility to benzene toxicity have been studied; however only the GSTM1 genotypes had a significant effect on urinary MA excretion. Our data indicates that children living in the areas of high traffic density are exposed to a higher level of benzene than those living in rural areas. Exposure to higher level of benzene in urban children may contribute to oxidative DNA damage, suggesting an increased health risk from traffic benzene emission.

Possibilities of rainwater utilisation in densely populated areas including precipitation runoffs from traffic surfaces

Although Germany is not considered a water-poor country, rainwater utilisation in households became widespread since the 1980s. Today, about 50,000 professional rainwater plants are being installed every year mostly in new one-family houses. These plants collect exclusively water from the roof which is filtered, stored and primarily used for toilet flushing, garden watering and household laundry. A novel approach in Germany is the use of the more polluted rainwater draining from streets and courtyard surfaces for treatment and reuse as service water, which is the topic of this paper. Intensive investigations have shown that rainwater needs to be treated if street runoffs are diverted to the cistern. Stormwater in this case originates from roofs, courtyards and a one-way street with low traffic density. Compared to high traffic density areas, the rainwater is relatively low polluted (COD: mean 14 mg/L, max 36 mg/L; BOD 7: mean 6.4 mg/L, max 45 mg/L; E. coli: median 1060/100 mL, max 43,000/100 mL). Treatment follows in a substrate filter (aerobic biological treatment) with an eventual UV disinfection of the treated rainwater. This treatment proved to be inexpensive with good effluent quality for use in toilet flushing and garden watering (COD: mean 6.8 mg/L, max 15.8 mg/L; BOD 7: mean 0.9 mg/L, max 3 mg/L; E. coli: median < 4/100 mL, max 43/100 mL). This form of harvesting could be considered a viable option for densely populated urban areas. It also contributes in reducing the drinking water consumption and wastewater production as well as minimising pollutant entry into surface waters, without the need for a sewer connection. About 70% of the toilet-flush demand (about 2500 m 3/a) was replaced by treated stormwater without any comfort loss. A total energy demand of only 0.88 kWh/m 3 is required for treatment and distribution. Compared to the Berlin drinking water quality, the use of the much softer rainwater has also the advantage of less lime depositions on sanitary facilities.

Effect of local and long-range transport emissions on the elemental composition of PM 10–2.5 and PM 2.5 in Beirut

The elemental composition of PM 10−2.5 and PM 2.5 were studied in winter, summer, stormy and non-stormy dates during a period extending from February 2004 till January 2005, in a populated area of Beirut. Results of PIXE analysis and enrichment factor (E.F.) calculation, using Si as a reference of crustal material, showed that crustal elements (E.F.<10) like Si, Ca, K, Ti, Mn and Fe were more abundant in PM 10−2.5 while enriched elements (E.F.>10) like S, Cu, Zn and Pb predominated in PM 2.5. In PM 10−2.5, concentrations of crustal elements increased during stormy episodes, all time high Ca concentrations were due to the abundance of calcite and limestone rocks in Lebanon, and increased Cl levels correlated with marine air masses. In PM 2.5, sulfur concentrations were more prominent in the summer due to the enhancement of photochemical reactions. Sources of sulfur were attributed to local, sea-water and long-range transport from Eastern Europe, with the latter being the most predominate. Anthropogenic elements like Cu and Zn were generated from worn brakes and tires in high traffic density area and spikes of Pb were directly linked to a southerly wind originated from Egypt and/or Israel as determined by the air trajectory HYSPLIT model. In brief, elemental variations depended on the regional variability of the transport pattern and the different removal rates of aerosols.

Increased health risk in Bangkok children exposed to polycyclic aromatic hydrocarbons from traffic-related sources

The aim of this study is to assess potential health risk of exposure to particle-associated polycyclic aromatic hydrocarbons (PAHs) in children living in a megacity with traffic congestion such as Bangkok. The study population comprised 184 Thai schoolboys (aged 8-13 years) attending schools adjacent to high-density traffic areas in Bangkok and schools located in the provincial area of Chonburi. The ambient concentration of total PAHs at roadsides in proximity to the Bangkok schools was 30-fold greater than at roadsides in proximity to the provincial schools (30.39 +/- 5.80 versus 1.50 +/- 0.28 ng/m(3); P < 0.001). Benzo(g,h,i)perylene (BghiP), an indicator of automobile exhaust emission, was the predominant PAH. Personal exposure to total PAHs and the corresponding benzo(a)pyrene (BaP) equivalent concentrations in Bangkok schoolchildren were 3.5-fold higher than in provincial schoolchildren (4.13 +/- 0.21 versus 1.18 +/- 0.09 ng/m(3); P < 0.001 and 1.50 +/- 0.12 versus 0.43 +/- 0.05 ng/m(3); P < 0.001, respectively). The concentration of urinary 1-hydroxypyrene (1-HOP) was significantly higher in Bangkok schoolchildren. Bulky carcinogen-DNA adduct levels in peripheral lymphocytes were also significantly higher (0.45 +/- 0.03 versus 0.09 +/- 0.00 adducts/10(8) nt; P < 0.001). Finally, a significantly higher level of DNA strand breaks and a significantly lower level of DNA repair capacity were observed in Bangkok schoolchildren (P < 0.001). This study indicates that Bangkok schoolchildren exposed to a high level of genotoxic PAHs in ambient air may be more vulnerable to the health impacts associated with the exposure to genotoxic pollutants than children in provincial areas and may have increased health risks for the development of certain diseases such as cancer.

Heavy Metals Content in N. OleanderLeaves As Urban Pollution Assessment

Nerium oleander L. (Oleander) leaves grown in Palermo city (Sicily, Italy) were collected from six sampling sites representing either areas of high traffic and urbanisation density or areas far away from traffic (e.g. city gardens). Concentration of Al, Ba, Cr, Cu, Fe, Pb, Mg, Mn, and Zn were determined in leaf samples during two years. Multivariate analysis classified the sampling sites in four groups based on the metal content in vegetal leaves in agreement with traffic and human activity site. Many elements studied (Al, Ba, Fe, Mn Mg) arise from the soil composition and others such as Cr, Cu, Pb and Zn as pollutant of the soil. On the other hand, about 30% of Al, Fe Cr, Cu and Pb originate from aerial deposition on leaves. Although the results presented should be handled with caution N. oleander can be considered as a means of assessing dust contamination in the urban environment.

Soil radioactivity and radiation absorbed dose rates at roadsides in high-traffic density areas in Ibadan metropolis, southwestern Nigeria

The effect of ionising radiation on biological systems depends among other factors on time and place of exposure and population involved. Socio-economic factors in human daily activities have subjected humans to certain environmental health risks. In most cases the risk appears to be higher outdoors than indoors. In order to quantify the radiation exposure levels to individuals in the outdoors in areas with high human and vehicular densities, roadside soil samples were collected from major bus stops and round-about in the metropolis of Ibadan and were analysed for their activity concentration levels using gamma-ray spectrometry. The 40K activity concentration ranged between 96.1 and 336.5 Bq kg(-1) with a mean of 219.8 +/- 71.4 Bq kg(-1); 238U was in the range of 10.2-40.7 Bq kg(-1) with a mean of 20.3 +/- 6.9 Bq kg(-1) while that of 232Th ranged between 13.3 and 29.7 Bq kg(-1) with a mean of 21.2 +/- 5.3 Bq kg(-1). The total gamma absorbed dose rates in air ranged between 17.2 and 41.8 nGy h(-1) with an average of 32.0 +/- 5.8 nGy h(-1). The gamma absorbed dose rates at the roadsides in traffic density areas were found to be lower when compared with previously reported values in natural and undisturbed locations in non-traffic density areas in the city.

En-route sector capacity estimation methodologies: An international survey

Reliable estimation of en-route sector capacity is important, especially in high-density traffic areas where controller workload is the driver. En-route sector capacity is commonly estimated using fast-time computer simulation techniques employing models of controller workload. This paper analyses the methodologies employed by a number of countries in Europe and North America, to estimate the capacity of en-route airspace. The data used was obtained from airspace planners and managers. The survey involved interviews using pre-designed questionnaires. The results show that there are two main models used in the simulation of controller workload, and that there is considerable variation both in their application and controller involvement in the capacity estimation process.

Spatiotemporal patterns in foliar element concentrations in Ficus microcarpa L. f. growing in an urban area: implications for biomonitoring studies

Abstract Effects of atmospheric pollution and seasonal variation on Al, Ba, Cr, Cu, Fe, Mg, Mn, Pb, V and Zn concentration in Indian laurel (Ficus microcarpa L. f.) leaves were studied in the city of Palermo (Sicily, Italy). Samples were collected from six sampling sites representing either (a) areas of high traffic density or (b) areas further away from traffic (e.g. gardens). Samples were collected every two months during 1998 and 2000. Apart from Ba, Cr and Mn, the elements showed a significant temporal variation but no consistent trends in this were present; the highest (or lowest) values were not detected at some particular time of the year. Results show that the progressive phasing-out of leaded petrol in Italy has resulted in a decrease of Pb, whereas we detected some indications to increased foliar V in the course of time. Even though some spatial patterns were seen in some of the elements, concentrations were not significantly higher in areas representing high traffic density than in samples collected from gardens. Hence, our results do not give unreserved support to use F. microcarpa as a biomonitor.

Could Ornamental Plants Serve as Passive Biomonitors in Urban Areas?

A search for cheap and efficient method to monitor atmospheric particulates in city centres has raised new interest to measure foliar element concentrations after the role of particulate pollution for respiratory illnesses was discovered. Leaf samples of Golden dewdrop (Duranta repens L.) collected in Palermo (South of Italy) between 1998 and 2000 were analysed to study the possible use of this shrub as a passive biomonitor for atmospheric pollution in urban areas. Concentrations of Ba, Cd, Cu, Fe, Mg, Mn, Pb and Zn were determined from leaf samples collected from six sampling sites representing either (a) areas of high traffic density or (b) areas not directly affected by the city traffic (e.g. gardens). Most of the elements showed a significant temporal variation but no consistent trends could be seen, i.e. the highest (or lowest) values were not detected consistently at some particular time of the year. Furthermore temporal changes were of same magnitude in polluted versus less polluted areas; no statistically significant interaction between pollution level and collection period was detected. Pollution level (traffic density) was the primary factor to explain spatial variation only in the case of foliar Mg concentrations. On the other hand, variation in foliar concentrations between sampling sites (irrespective of the pollution level) was large. Our results suggest that particulate deposition needs to be quite high before spatial segregation can be done on the basis of foliar element concentrations.

TRAFFIC DENSITY AS A RISK FACTOR FOR CHILDHOOD ASTHMA

ISEE-129 Abstract: The object of this study was to determine whether children who live in high traffic areas have a greater risk of developing asthma. The parents of kindergarten and first grade children in thirteen schools were surveyed for asthma symptoms in their child, doctor’s diagnosis of asthma, household risk factors, and history of parental asthma. The household location was placed on a Geographic Information Systems (GIS) map and a buffer of 100 meters (one city block) and 300 meters was drawn around each location. Two traffic exposure variables were created for each child by measuring the length of all segments of roadways falling within the two buffers and multiplying by the average daily traffic count on that roadway at that location. These calculated exposure variables were categorized into low, medium and high traffic density exposure based on percentiles of the distribution. Over 1100 surveys were returned. Overall rate of doctor diagnosed asthma for kindergarten and first-grade children was 11%. Traffic exposure was calculated for the 100-meter buffer (traffic density within one city block) and the 300-meter buffer (traffic density within 3 blocks of the residence). Multiple logistic regressions and spatial regression were done with doctor-diagnosed asthma as the dependent variable and traffic exposure as an independent variable. Other independent variables included parental asthma, smoker in the house, family income, and gender. The results show that the adjusted odds ratio for children being diagnosed with asthma was 2.38 (1.19, 4.76) for high traffic within 100 meters of residence and 2.74 (1.35, 5.56) for high traffic within 300 meters of residence. As it is unlikely that parents of children with asthma preferentially move to areas of high traffic density, this study indicates that living close to high traffic areas may be a risk factor for receiving a diagnosis of asthma in early childhood. Further studies are needed to confirm this hypothesis.

Residential exposure to traffic in California and childhood cancer.

Motor vehicle emissions are a major source of air pollution in California. Past studies have suggested that traffic-related exposures can increase the risk of childhood cancer, particularly leukemia. From California's statewide, population-based cancer registry, we identified cancers diagnosed in children younger than 5 years of age between 1988 and 1997. We matched these cases to California birth certificates. For each case, we randomly selected 2 control birth certificates, matched by birth date and sex. For each mother's residential address at the time of her child's birth, we calculated road density by summing the length of all roads within a 500-foot radius of the residence. Traffic density was based on road lengths and vehicle traffic counts for highways and major roads. The distributions of road and traffic density values were very similar for the 4369 cases and 8730 matched control subjects. For all cancer sites combined, the odds ratio (OR) for the highest road density exposure category, compared with the lowest, was 0.87 (95% confidence interval [CI] = 0.75-1.00). For all sites combined and for leukemia, the ORs were also below 1.0 for the highest traffic density exposure category (0.92 for both). For central nervous system tumors, the OR was 1.22 (CI = 0.87-1.70). In a large study with good power, we found no increased cancer risk among offspring of mothers living in high traffic density areas for all cancer sites or leukemia.

Traffic density in California: socioeconomic and ethnic differences among potentially exposed children.

Motor vehicles are the main source of many hazardous air pollutants in California. Previous studies have shown that low-income and minority populations are more likely to live near industrial sources of pollution and in areas that do not meet national air quality standards. We estimated neighborhood exposures to motor vehicle emissions from a road network with daily traffic counts using a geographic information system. To calculate traffic density, we summed the average daily vehicle miles of travel per square mile of land area for each census block group in the state. We used 1990 census data to characterize the population by age, race and socioeconomic status in block groups with high traffic density. Block groups with more than 500,000 vehicle miles of travel per square mile were defined to be high traffic density. Statewide, about 5% of all block groups met this criterion and more than 215,000 children under 15 years of age lived in these high traffic density areas. Block groups in the lowest quartile of median family income were three times more likely to have high traffic density than block groups in the highest income quartile. The percentage of children living in high traffic density block groups increased with decreasing median family income for all race and ethnicities except White. Overall, children of color were about three times more likely to live in high-traffic areas than were white children. Based on this analysis, low-income and children of color have higher potential exposure to vehicle emissions. Future exposure assessment studies should target the highest traffic density areas, and health studies should consider the differences by income and race or ethnicity during design.

Do leaf surface characters play a role in plant resistance to auto-exhaust pollution?

Summary The significance of micro-morphologica1 leaf surface characters of plants in indication and mitigation of auto-exhaust pollution has been investigated. For the purpose of the study, the following plant species growing along roadsides in low and high traffic density areas have been selected: Asparagus racemosus , Azadirachta indica , Bougainvillea spectabilis , Cassia fistula , Ficus religiosa , Nerium indicum , Polyalthia longifolia and Thevetia neriifolia . These plants were continuously exposed to automobile emissions. As compared to control plants, the leaf surface structures changed significantly in the exposed plants. The epidermal cells collapsed, cell boundaries were irregularly fused, and a two-fold increase in stomatal frequency and trichome length could be observed. Epicuticular wax also lost its original shape, got disorganised and subsequently eroded, forming patches of a crust on the cuticle. While the surface structural changes were significant, the phenology of these plants remained unaffected by auto-exhaust pollution. The investigated species though manifesting above changes remained normal and healthy and, therefore, they may be recommended for growing along roadsides in areas polluted by automobile emissions.

Possible Relevance of Pigeons as an Indicator Species for Monitoring Air Pollution

Wild city pigeons were caught at four different locations in the Netherlands to represent areas of high (Amsterdam-high), moderate (Amsterdam-medium), and low (Maastricht and Assen) traffic density. It is assumed that local ambient air pollution decreases as a function of traffic density. In these pigeons levels of polycyclic aromatic hydrocarbon (PAH)-DNA adducts, oxidative DNA damage, and heavy metal residues were determined in kidney, lung, liver, and blood (no adduct analysis in blood). The contribution of leaded gasoline to total body lead content was estimated by measuring concentrations of Pb and its isotopes in blood. We also analyzed samples of ambient air particulate matter for PAH and heavy metal concentrations at the four different locations. Interregional differences in heavy metals in ambient air particulate matter were reflected relatively well by pigeon body loads. The higher lead and cadmium concentrations in blood, kidney, liver, and lung were found in the Amsterdam high traffic density area, followed by Amsterdam medium, Assen, and Maastricht. A high Pb concentration in blood coincided with relatively low 206Pb/207Pb values, indicating a high contribution of leaded gasoline to total blood Pb concentrations in pigeons from the Amsterdam high traffic density area. Significantly enhanced blood zinc values were found in pigeons from both locations in Amsterdam compared to pigeons from the other two areas. However, no differences in Zn tissue levels between the four different groups were found. Oxidative DNA damage, determined as the ratio of 7-Hydro-8-oxo-2'-deoxyguanosine/ deoxyguanosine, in pigeon liver was highest in Amsterdam-high, followed by Assen (low traffic density). Pb content, but not the Cd content, was positively associated with oxidative DNA damage in liver tissue. In lung tissue, a negative correlation was found between oxidative DNA damage and Zn content. These results indicate that the carcinogenic potential of Pb might be ascribed to oxygen radical formation, whereas Zn plays a protective role against oxidative DNA damage. Places with high and medium traffic density could be clearly discriminated on the basis of PAH levels in the ambient air. The PAH content in particulate air samples was not, however, reflected in total PAH-related DNA adduct levels because no differences could be observed in tissue adduct levels in pigeons from the four different locations. Our results indicate that wild city pigeons can be used as biological indicators of exposure to heavy metal pollution in outdoor air.

Suspended particulates in the Jamaican atmosphere

The results of a survey of air particulates at 23 sites across Jamaica for total suspended particulates (TSP), Al, Br, Cl, Na, Pb, and V, by instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF) are reported. The geometric mean of TSP values, 35 g m-3, is well within the World Health Organisation's standard of 60 g m-3 for TSP, but in areas of high vehicular traffic density the TSP values exceeded this limit. The correlation coefficient between Br and Pb concentrations in the particulates was 0.92 and the Br/Pb ratio of 0.38 compares well with a ratio of 0.39 found in commercial petrol indicating that the exhaust from vehicular traffic is the major source of Pb in atmospheric particulate matter in Jamaica.

Contamination of roadside soil and grass with heavy metals

The concentrations of heavy metals were determined in roadside soil and grass from different locations in Ibadan metropolis and two highways. The levels found (in μg g −1) were: Cr - 20.6-104; Mn - 86.2-355; Fe - 1737-4455; Ni - 10.9-115; Cu - 8.94-80.5; Zn - 43.5-213; Cd - 0.18-2.70; and Pb - 205-730. There was no significant difference (P < 0.10) between the mean concentrations of these metals in the high and low traffic density areas suggesting that sources other than the motorcar also influence the levels of these metals in roadside soil and grass.

Aromatic DNA adducts in lymphocytes of humans working at high and low traffic density areas

Aromatic DNA adduct levels were determined by the 32P-postlabelling assay in lymphocytes isolated from newspaper vendors working at urban high traffic areas ( n = 31) and suburban low traffic areas ( n = 22) in Milan, Italy. The DNA adduct levels ranged from 0.7 to 6.7 10 8 nucleotides, while most of them were between 1.0 and 3.0 10 8 nucleotides. No difference was found between the DNA adduct levels of the high-exposed group ( 2.2 10 8 ) and the low-exposed group ( 2.2 10 8 ). The heavy smokers ( n = 8) had 23% higher DNA adduct level ( 2.7 10 8 ) than the non-smokers ( n = 37, 2.2 10 8 ) ( P = 0.27), but no correlation was found between the adduct level and the number of cigarettes/day. Analysis of variance of the DNA adduct levels among the 14 pairs of individuals working at the same news-stands revealed little effect of the environmental air exposure on the DNA adduct level.

Spatial and temporal patterns in heavy metals concentration in street dust in a hot desert region

This investigation reports temporal and spatial variations in heavy metal concentration in street dusts in the State of Bahrain. Monitoring sites were chosen to include an urban area with high traffic density, commercial, industrial, and remote areas. The overall mean levels for Pb, Zn, Ni, Cu and Cd were 395, 80, 40, 20 and 1.5 mg kg‐1, respectively. The general pattern of occurrence in order of decreasing concentration was Pb > Zn > Ni > Cu > Cd. The highest levels of Pb, Zn and Cu were found in the high traffic density area, and strong positive correlations were found between these metals, suggesting that automobiles exhaust are the dominant source of these metals. The results did not reveal statistically significant differences on the levels of Pb, Zn and Cu between months. Summer average values for Pb, Zn and Cu exceeded corresponding winter values. In cold regions opposite patterns were observed. In general Ni and Cd followed different patterns than that reported for Pb, Zn and Cu. Our results revea...

Risk of Collision at Sea

Vessel traffic service systems (VTS systems) have been established, throughout the world, in areas of high traffic density. These systems, operating with such tools as VHF radiotelephony, land-based radar installations and ship's data processing, gather information to respond to collision and grounding danger, to organize traffic flow and assist allied activities. It is expected that VTS systems should effectively reduce the number of collisions in the VTS area. But efforts for collision avoidance can only be successful if the VTS operator in front of the shoreside radar screen is precisely instructed as to which measurements he has to make to identify a risk-of-collision situation. Uncertainties about the direction in which ships must take evasive action arise in VTS areas, where ships are free to engage in encounters.