Vehicle-related Pollution Research Articles

CALINE4 and AERMOD modelling for roadway vehicle-related air pollution: a recent review in India.

Modelling and prediction of air quality facilitates the drafting of efficient guidelines and, in turn, proper management of adversely affected areas. In order to depict the air pollutants in urban centres, this research analyses two modelling tools: AERMOD and CALINE4. Both technologies provide distinct capabilities in the modelling of air quality from vehicular and other emissions. CALINE4, a Gaussian dispersion model, specifies pollutant dispersion from mobile sources along roadways. It boasts a user-friendly interface and road-specific modelling capabilities, factoring in traffic speed and vehicle emissions. However, it simplifies intricate flow patterns and relies on primary meteorological data. On the other hand, AERMOD is a versatile model suitable for various emission sources, including both mobile and stationary sources. It excels at capturing diverse atmospheric processes but demands precise meteorological, terrain, and emission data. AERMOD is often preferred for regulatory compliance assessments, although it entails a steeper learning curve and higher computational requirements. The choice between CALINE4 and AERMOD hinges on study needs, data availability, and desired modelling precision. This review offers an overview to assist researchers in making informed model selections for assessing vehicle-related pollution, critical aspects of urban sustainability, and air quality management.

Assessment of light-duty versus heavy-duty diesel on-road mobile source emissions using general additive models applied to traffic volume and air quality data and COVID-19 responses

ABSTRACT Following the outbreak of the COVID-19 pandemic, several papers have examined the effect of the pandemic response on urban air pollution worldwide. This study uses observed traffic volume and near-road air pollution data for black carbon (BC), oxides of nitrogen (NOx), and carbon monoxide (CO) to estimate the emissions contributions of light-duty and heavy-duty diesel vehicles in five cities in the continental United States. Analysis of mobile source impacts in the near-road environment has several health and environmental justice implications. Data from the initial COVID-19 response period, defined as March to May in 2020, were used with data from the same period over the previous two years to develop general additive models (GAMs) to quantify the emissions impact of each vehicle class. The model estimated that light-duty traffic contributes 4–69%, 14–65%, and 21–97% of BC, NOx, and CO near-road levels, respectively. Heavy-duty diesel traffic contributes an estimated 26–46%, 17–63%, and −7–18% of near-road levels of the three pollutants. The estimated mobile source impacts were used to calculate NOx to CO and BC to NOx emission ratios, which were between 0.21–0.32 μg m−3 NOx (μg m−3 CO)−1 and 0.013–0.018 μg m−3 BC (μg m−3 NOx)−1. These ratios can be used to assess existing emission inventories for use in determining air pollution standards. These results agree moderately well with recent National Emissions Inventory estimates and other empirically-derived estimates, showing similar trends among the pollutants. However, a limitation of this study was the recurring presence of an implausible air pollution impact estimate in 41% of the site-pollutant combinations, where a vehicle class was estimated to account for either a negative impact or an impact higher than the total estimated pollutant concentration. The variations seen in the GAM estimates are likely a result of location-specific factors, including fleet composition, external pollution sources, and traffic volumes. Implications: Drastic reductions in traffic and air pollution during the lockdowns of the COVID-19 pandemic present a unique opportunity to assess vehicle emissions. A General Additive Modeling approach is developed to relate traffic levels, observed air pollution, and meteorology to identify the amount vehicle types contribute to near-road levels of traffic-related air pollutants (TRAPs), which is important for future emission regulation and policy, given the significant health and environmental justice implications of vehicle-related pollution along major roadways. The model is used to evaluate emission inventories in the near-road environment, which can be used to refine existing estimates. By developing a locally data-driven method to readily characterize impacts and distinguish between heavy and light duty vehicle effects, local regulations can be used to target policies in major cities around the country, thus addressing local health disbenefits and disparities occurring as a result of exposure to near-road air pollution.

CFD Simulation of Particle Diffusion at the Region near the Entrance or Exit of An Underground Parking Lot

Abstract: Nanoparticles have been demonstrated to have severely adverse impact on human health. As underground parking lot is a typical enclosed space with huge amount of vehicle-related particles, particle diffusion and pollution should be of great importance. The study employed a three-dimensional numerical model to simulate particle concentration distribution under transient natural wind through the entrance of the underground parking lot. The simulation results demonstrated that particle diffusion was controlled by natural wind through the entrance when vehicle stopped exhaust. Natural wind is an effective way to dilute nanoparticles exhausted by vehicles and contributed to a more uniform distribution of nanoparticles near the entrance in the parking lot. The results could provide fundamentals for the future application of ventilation design, and can be used to assess human exposure to vehicle particle pollutants at underground parking facilities.

Road-Edge Effects on Herpetofauna in a Lowland Amazonian Rainforest

The impact of roads on the flora and fauna of Neotropical rainforest is perhaps the single biggest driver of habitat modification and population declines in these ecosystems. We investigated the road-edge effect of a low-use dirt road on amphibian and reptile abundance, diversity, and composition within adjacent lowland Amazonian rainforest at San Jose de Payamino, Ecuador. The road has been closed to vehicle traffic since its construction in 2010. Thus, effects from vehicle mortality, vehicle-related pollution, and road noise were not confounding factors. Herpetofauna were surveyed using both visual encounter surveys and drift fences with pitfall and funnel traps at varying distances from the road. Structural and microclimate features of the forest were measured at each sampling distance. Several habitat variables were found to differ at intermediate and interior sampling distances from the road compared to forest edge conditions, suggesting the road-edge effect began to attenuate by the intermediate sam...

Prevalence of wide area impacts downwind of freeways under pre-sunrise stable atmospheric conditions

In urban areas, a large fraction of the population typically lives within 1.5–2 km of a freeway. In an earlier study, Hu et al. (2009) showed that in the pre-sunrise hours, with stable, nocturnal meteorological conditions, the vehicle-related pollution from a freeway in southern California extended more than 2 km downwind. This was in striking contrast to earlier studies in the U.S. and Australia showing that during the daytime pollutant concentrations extended no more than ∼300 m downwind of major roadways. The present study was designed to explore the variability of the large downwind pollutant impact zone observed by Hu et al. (2009) in the pre-sunrise hours on a wider geographic scale. An instrumented mobile platform was employed to measure vehicle-related pollutant concentrations on transects running upwind and downwind of four freeways in the coastal, central and eastern areas of the California South Coast Air Basin (SoCAB) during the pre-sunrise period (04:30–06:30). Extended freeway plumes were observed for ultrafine particles (UFP), nitric oxide and particle-bound polycyclic aromatic hydrocarbons (PAH) at all four sites during stable pre-sunrise periods. Plume lengths were measured to be ∼2 km or more with a dilution rate coefficient about a factor of ten lower than commonly observed for daytime. An average of 39 and 19% (±8–9%) of freeway plume peak concentrations of UFP remained 500 and 1500 m downwind, respectively, from the freeways for the four transects studied here. Because a large fraction of UFP and other vehicle related pollutants typically penetrate into indoor environments, and nocturnal surface inversions are widespread across the globe, our findings have significant implications for more extensive human exposures to vehicle-related pollutants than previously indicated based on daytime measurements of roadway plumes.

Assessing geochemical influence of traffic and other vehicle-related activities on heavy metal contamination in urban soils of Kerman city, using a GIS-based approach

Heavy metal pollution caused by traffic activities is increasingly becoming a great threat to urban environmental quality and human health. In this paper, soils of Kerman urban and suburban areas were collected to assess the potential effects of traffic and other vehicle-related pollution by heavy metal accumulation in soils. Eighty-six samples were collected along streets and from residential and rural sectors, as well as vehicle-related workshops from depth of 0-5 and 15-20cm and analyzed by flame atomic absorption spectrometry (FAAS) for heavy metals (Cd, Cr, Cu, Pb, Sn and Zn), as well as major elements (Al, Ca, Fe and Mn). Several hot-spot areas were identified in the composite geochemical maps produced based on Geographical Information System (GIS) technology. The majority of the hot-spot areas were identified to be vehicle-related workshops, fuel stations and road junctions. The most polluted hot-spot in the study area was located in soils close to a car battery processing workshop in the southwestern part of Kerman city, with concentrations of Cd (0.32mg/kg), Cr (169mg/kg), Cu (250mg/kg), Pb (5,780mg/kg), Sn (27.2mg/kg) and Zn (178mg/kg) of 1, 8.5, 8.3, 230, 13.5 and 3 times more than the relevant mean concentrations in natural soils, respectively. Traffic pollution has resulted in significant accumulation of heavy metals in soils and sediments, and that level of accumulation varied remarkably among elements. Based on X-ray diffraction analysis, most parts of soils and sediments of the Kerman basement consist of calcite and clay minerals. Abundance of clay minerals and medium to alkaline pH causes low mobility of heavy metals in soils of Kerman.

The challenge of air pollution research

The four papers in this issue, marking the third anniversary of Air Quality, Atmosphere, and Health, illustrate the complexity of research on air pollution and the need for a multidisciplinary journal like this one. The research was carried out by authors in multiple countries (Brazil, Malaysia, and the USA), and the evidence covered is diverse, being based in atmospheric sciences, economics, epidemiology, and toxicology. The main topics covered include the atmospheric and health impacts of traffic in urban environments, the determinants of pollutant concentrations in complex urban environments, the presence and implications of ultrafine particles in urban atmospheres, and the economic evaluation of the benefits of air pollution control. All of these topics are integral to evidence-based control of air pollution. Two of the papers are based on air pollution in cities in middle-income countries where air pollution remains a threat to public health: Sao Paulo, Brazil, and locations within the Klang Valley, Malaysia. The Sao Paulo study by Martins et al. (2010) was carried out in one of the world's largest megacities and one that is notorious for its traffic. Their measurements and modeling captured the complicated temporal variation of pollutant levels within the city and the driving influence of traffic. They also captured a component that was possibly reflective of widespread biomass burning. They emphasize the presence of ultrafines in the atmosphere of Sao Paulo and use modeling to highlight the potential risks to health. Azmi and colleagues (2010) document air quality in the industrialized Klang Valley of Malaysia. As in Sao Paulo, heavy traffic plays a key role in driving air pollutant concentrations, and biomass burning has had a strong influence at times. Both studies should prove useful for informing local decision-making around air quality control strategies. Grahame and Schlesinger (2010) have carried out a critical review that is relevant to interpreting the findings of the studies in Brazil and Malaysia. They consider the rapidly growing literature on traffic emissions and cardiovascular outcomes, integrating findings of epidemiologic and toxicologic research. They conclude that vehicle emissions are a major contributor to cardiovascular morbidity and mortality in the USA. This conclusion implies that the higher levels of vehicle-related pollution in lowerand middle-income countries, like Brazil and Malaysia, must also be causing adverse cardiovascular health effects. The Health Effects Institute recently published a systematic review of the evidence on exposure to traffic-related pollution and health (Health Effects Institute 2009). This review also found epidemiological and toxicologic evidence for adverse cardiovascular effects, although uncertainties were sufficient to preclude a designation of the evidence as firmly in support of causation. While Grahame and Schlesinger recommend consideration of a black carbon standard to address traffic emissions, the Health Effects Institute did not find sufficient evidence to recommend a particular indicator for monitoring. Recently, the US Environmental Protection Agency promulgated a National Ambient Air Quality Standard (NAAQS) for NO2 that calls for a new monitoring network directed at near-roadway exposures of the population (Federal Register 2010). The resulting data will provide insights into the population profile of exposure to traffic emissions. J. M. Samet (*) Department of Preventive Medicine, Keck School of Medicine and Institute for Global Health, University of Southern California, Los Angeles, CA 90089, USA e-mail: jsamet@usc.edu

Near-road air pollution impacts of goods movement in communities adjacent to the Ports of Los Angeles and Long Beach

A mobile platform was outfitted with real-time instruments to spatially characterize pollution concentrations in communities adjacent to the Ports of Los Angeles and Long Beach, communities heavily impacted by emissions related to dieselized goods movement, with the highest localized air pollution impacts due to heavy-duty diesel trucks (HDDT). Measurements were conducted in the winter and summer of 2007 on fixed routes driven both morning and afternoon. Diesel-related pollutant concentrations such as black carbon, nitric oxide, ultrafine particles, and particle-bound polycyclic aromatic hydrocarbons were frequently elevated two to five times within 150 m downwind of freeways (compared to more than 150 m) and up to two times within 150 m downwind of arterial roads with significant amounts of diesel traffic. While wind direction was the dominant factor associated with downwind impacts, steady and consistent wind direction was not required to produce; high impacts were observed when a given area was downwind of a major roadway for any significant fraction of time. This suggests elevated pollution impacts downwind of freeways and of busy arterials are continuously occurring on one side of the road or the other, depending on wind direction. The diesel truck traffic in the area studied was high, with more than 2000 trucks per peak hour on the freeway and two- to six-hundred trucks per hour on the arterial roads studied. These results suggest that similarly-frequent impacts occur throughout urban areas in rough proportion to diesel truck traffic fractions. Thus, persons living or working near and downwind of busy roadways can have several-fold higher exposures to diesel vehicle-related pollution than would be predicted by ambient measurements in non-impacted locations.

Short-Term Particulate Threat: Pollution Standard May Not Protect Health

Many studies have shown that particulate matter (PM) poses health risks, yet the attributes of PM that cause these effects remain uncertain. To address some of those critical nuances, especially the short-term effects of specific emissions, researchers used a refined approach, including new application of a pollutant distribution model, to assess links between deaths and two PM components, black carbon and sulfate particles [EHP 115:751–755; Maynard et al.]. They found that as the air concentration of either component increased, there were more deaths the following day. These results occurred even at concentrations below current U.S. standards for fine particulates. Sulfate exposure in the northeastern United States comes in large part from coal-fired power plants. Black carbon is a surrogate for vehicle-related pollution that varies significantly over short distances. The researchers used data from a central monitor at the Harvard School of Public Health to determine concentrations of sulfates and assumed there were homogenous concentrations throughout the study area, a premise other studies have validated. To estimate concentrations of black carbon, they used a model that began its calculations with daily data from another monitor at the school. The model then estimated black carbon concentrations at more than 80 representative sites in the Boston area, incorporating variables such as weather, season, day of week, traffic volume, proximity to major roadways, population density, and percent urbanization. The researchers also accounted for gender, education, income, and residence location for each death. In evaluating 107,925 deaths that occurred at Boston-area residences from 1995 through 2002, the researchers found that each interquartile increase in black carbon concentration on the day before death was linked with a 2.3% rise in deaths from any cause and a 4.4% increase in stroke deaths. A similar, though smaller, relationship existed for sulfate particles, with each interquartile increase the day before death linked with a 1.1% increase in death from any cause. The researchers also found that for both black carbon and sulfates, there were increases of similar magnitude for deaths from cardiovascular disease, respiratory diseases, and diabetes. The authors acknowledge that the black carbon estimation model still needs refinement, that the study was limited by its focus on just one city, and that there were relatively limited data for sulfates and some causes of death. Nonetheless, this work confirms past research implicating sulfates and black carbon in the PM–mortality association. As a result, the authors say their findings reinforce concerns that current and proposed fine particulate standards do not adequately protect public health.

Proximity of Licensed Child Care Facilities to Near-Roadway Vehicle Pollution

We assessed child care facilities' proximity to heavily traveled roadways in an attempt to estimate the extent of potential exposure of young children to vehicle-related pollution in this understudied microenvironment. We examined approximately 24,000 licensed child care facilities in California located within 200 m of heavily traveled roadways. Approximately 57000 of the available slots in California child care centers (7% of the overall capacity) are in facilities located within 200 m (650 ft) of roadways averaging 50000 or more vehicles per day, and another 172000 (21%) are in facilities located within 200 m of roadways averaging 25,000 to 49,000 vehicles per day. Facilities providing care to infants or preschool-aged children and facilities located in disadvantaged areas were more often situated in medium-or high-traffic areas. Additional research is needed to further clarify the significance of the child care microenvironment in terms of potential childhood exposures to vehicle-related pollutants. Design strategies, notification standards, and distance-based siting restrictions should be considered in the facility licensing process and in land use and transportation planning.

Elaboration d'un indice d'exposition a la pollution atmospherique d'origine automobile a l'usage des etudes epidemiologiques

Air pollution due to motor vehicles is a worrying issue, in particular in the urban environment, all the more as a number of pollutants such as benzene and PAH are known to have carcinogenic effects. Epidemiological studies seem to be required, so a cumulated score of exposure must be developed. A correlation with pathology should be investigated. The calculation of an index of exposure to motor vehicle-related pollution requires a good assessment of pollutant emissions and a precise knowledge of pollutant transfer mechanisms by advection and spreading in built-up areas. In this study, it is proposed to use current theoretical and experimental knowledge to develop a calculation algorithm for this index. The following issues will be addressed in the presentation: an analysis of epidemiological requirements and of constraints of data acquisition using questionnaire surveys; a model for assessing, for each residential area, the average annual concentration of gaseous pollutants from motor vehicles. It will consider the environment geometry, traffic emissions and wind distributions. The model CALINE3 is used for open areas near roads and highways and the Danish model OSPM is introduced for street canyon environments.