Traffic-related Pollution Research Articles

Forecasting the Amount of Traffic-Related Pollutant Emissions by Neural Networks

Forecasting the Amount of Traffic-Related Pollutant Emissions by Neural Networks

Connections between air pollution, traffic and respiratory health

Air pollution increases the likelihood of developing a variety of health issues, particularly in the field of respiration. Involuntary exposure to traffic-related air pollution affects humans from fetal development to death. Nitrogen dioxide, sulfur dioxide, carbon monoxide, benzene, ozone, particulate matter 10 (PM10), lead, arsenic, cadmium, nickel, benzopyrene, and particulate matter 2.5 (PM2.5) are among the lung-damaging substances found in air pollutants. Determining the causal relationship between various major road pollutants and the human respiratory system is a difficult task. In general, it can be concluded that traffic-related pollutants will induce an inflammatory response that will progress based on the variation of humans exposed. The concept of oxidative stress resulting from traffic-related pollutants has also begun to receive extensive research. This gives hope for assisting the human anti-oxidant system in combating the increasingly difficult-to-avoid threat of air pollution.

Pedestrian-Aware Supervisory Control System Interactive Optimization of Connected Hybrid Electric Vehicles via Fuzzy Adaptive Cost Map and Bees Algorithm

Electrified vehicles are increasingly being seen as a means of mitigating the pressing concerns of traffic-related pollution. Due to the nature of engine-assisted vehicle exhaust systems, pedestrians in close proximity to these vehicles may experience events where specific emission concentrations are high enough to cause health effects. To minimize pedestrians’ exposure to vehicle emissions and pollutants nearby, we present a pedestrian-aware supervisory control system for connected hybrid electric vehicles by proposing an interactive optimization methodology. This optimization methodology combines a novel fuzzy adaptive cost map and the bees algorithm to optimize power-split control parameters. It enables the self-regulation of interobjective weights of fuel and exhaust emissions based on the real-time pedestrian density information during the optimization process. The evaluation of the vehicle performance by using the proposed methodology is conducted on the realistic trip map involving pedestrian density information collected from the University College Dublin campus. Moreover, two bootstrap sampling techniques and effect of communication quality are both investigated in order to examine the robustness of the improved vehicle system. The results demonstrate that 14.42% mass of exhaust emissions can be reduced for the involved pedestrians, by using the developed fuzzy adaptive cost map.

Indoor-outdoor pollutant concentration modelling: a comprehensive urban air quality and exposure assessment

This paper is devoted to the investigation of the relationship between concentrations of traffic-related pollutants at pedestrian level in the street and indoor pollutant concentrations inside different rooms of different floors of a standard building. CFD modelling covering the whole urban environment, including the interior of a target building, is used to explicitly simulate wind flow and pollutant dispersion outdoors and indoors. A wide range of scenarios considering different percentage and location of open windows and different wind directions is investigated. A large variability of indoor pollutant concentrations is found depending on the floor and configuration of the open/closed windows, as well as the wind direction and its incidence angle. In general, indoor pollutant concentrations decrease with floor, but this decrease is different depending on the scenario and the room investigated. For some conditions, indoor concentrations higher than the spatially averaged values in the street (up to a ratio of 1.4) are found in some rooms due to the high pollutant concentrations close to open windows. This behavior may lead, on average, to higher exposure inside the room than outside although, in general, indoor pollutant concentrations are lower than that found in the street at pedestrian level. Results are averaged for all scenarios and rooms being the average ratio between indoor and oudoor concentrations 0.56 ± 0.24, which is in accordance with previous studies in real buildings. This paper opens to a unified approach for the assessment of air quality of the total indoor and outdoor environment.

Estimation of traffic emissions in a polycentric urban city based on a macroscopic approach

This paper presents a macroscopic dynamic modeling framework for road traffic emissions in an urban city that has numerous central business districts (CBDs). The framework combines a two-dimensional (2D) continuum dynamic traffic assignment (DTA) model that captures macroscopic features of traffic flow and a microscopic instantaneous emission model associated with the instantaneous speed and acceleration of traffic flow. A heterogeneous traveling population continuously distributed in space is classified according to the trip destinations chosen by travelers. Each copy of flow tends to select an optimal route with the minimum cost to destination by means of instantaneous traffic information. For each copy of flow, an unstructured finite volume method as well as a fast sweeping method is designed to solve the proposed model. In order to validate the feasibility of the model and algorithm, a case study is conducted as an example to study the macroscopic characteristics of traffic flow and predict traffic-related pollutants like NOx, VOC, CO2 and PM in urban areas.

Decision support for sustainable urban mobility: A case study of the Rhine-Ruhr area

• A framework for integrated innovation policy of sustainable urban mobility is set. • A multi-actor and multi-level approach is considered. • Transformation process is step-wise guided. • An interactive scenario-simulation tool for the decision makers is developed. • Mobility demand and supply must be balanced to transform sustainable urban future. Sustainable urban governance considers the simultaneous reduction of traffic-related pollution, social equity for mobility access, healthy market competition among the service providers, and convenient use of multi-modal transportation enabled by digital technologies. However, the rise of more complex urban systems challenges decision-making processes to design and implement environmentally sustainable, economically viable, and socially acceptable urban mobility systems. The paper sets an innovative and collaborative decision-making framework for integrated sustainable urban policy design. Firstly, schematic integration of urban flows from disintegrated operation systems toward fully integrated, inclusive, and sustainable urban systems is conceptualized. Based on this concept a multi-level decision-making process within urban mobility policies is designed relying on a Multi-Criteria Decision Aid (MCDA) for resource allocation decisions at the micro, meso, and macro levels. Thereby, a range of urban futures is adequately addressed, be it smart, sustainable city concepts, peri-urbanization, and business as usual scenarios. The integrated model for a pilot case of the metropolitan region of Rhine-Ruhr is tested in this paper. If Sustainable City scenario is the desired one, push and pull measures should be equally weighted. Based on MCDA sensitivity analysis, policy recommendations and a practical hands-on tool for urban planning are derived.

Associations of long-term ambient air pollution and traffic-related pollution with blood pressure and hypertension defined by the different guidelines worldwide: the CHCN-BTH study.

The assessment of the generalization of the strict hypertension definition in the 2017 ACC/AHA Hypertension Guideline from environmental condition remains sparse. The aims of this study are to investigate and compare the associations of ambient air pollution and traffic-related pollution (TRP) with hypertension defined by the different criteria. A total of 32,135 participants were recruited from the baseline survey of the CHCN-BTH in 2017. We defined hypertension as SBP/DBP ≥ 140/90mmHg according to the hypertension guidelines in China, Japan, Europe and ISH (traditional criteria) and defined as SBP/DBP ≥ 130/80mmHg according to the 2017 ACC/AHA Hypertension Guideline (strict criteria). A two-level generalized linear mixed models were applied to investigate the associations of air pollutants (i.e. PM2.5, SO2, NO2) and TRP with blood pressure (BP) measures and hypertension. Stratified analyses and two-pollutant models were also performed. The stronger associations of air pollutants were found in the hypertension defined by the strict criteria than that defined by the traditional criteria. The ORs per an IQR increase in PM2.5 were 1.17 (95% CI: 1.09, 1.25) for the strict criteria and 1.14 (95% CI: 1.06, 1.23) for the traditional criteria. The similar conditions were also observed for TRP. The above results were robust in both stratified analyses and two-pollutant models. Our study assessed the significance of the hypertension defined by the strict criteria from environmental aspect and called attention to the more adverse effects of air pollution and TRP on the earlier stage of hypertension.

Associations between long term air pollution exposure and first hospital admission for kidney and total urinary system diseases in the US Medicare population: nationwide longitudinal cohort study

ObjectiveTo estimate the associations between long term exposure to air pollution and the first hospital admission related to kidney and total urinary system diseases.DesignNationwide longitudinal cohort study.SettingData were collected from...

Can biodiverse streetscapes mitigate the effects of noise and air pollution on human wellbeing?

Most of the global population are urban, with inhabitants exposed to raised levels of pollution. Pollutants negatively impact human wellbeing, and can alter the structure and diversity of ecosystems. Contrastingly, urban biodiversity can positively contribute to human wellbeing. We know little, however, about whether the negative impacts of pollution on wellbeing could be lessened for householders living on more biodiverse streets, as the complex interlinkages between pollution, biodiversity and wellbeing have rarely been examined. Here, we used structural equation modelling to simultaneously test whether biodiversity (actual and perceived) mediates the relationship between traffic-related pollution (noise, dB; nitrogen dioxide, NO2) or air pollution (PM2.5) and wellbeing (mental wellbeing, happiness). In summer 2019, we conducted questionnaires and biodiversity surveys, and collected noise and air pollution data, from households (n = 282) across the streetscapes of Leeds, UK. Biodiversity (actual or perceived) showed no mediating effects. However, increased flowering plant richness was positively associated with mental wellbeing. Traffic-related pollution negatively affected pollinator and flowering plant richness, but not wellbeing. This could be because householders are not exposed to high levels of noise or NO2 because they do not maintain front gardens on noisier streets. There was no measurable effect of air pollution on biodiversity or wellbeing. These findings shed light on the complex mechanisms through which biodiversity could improve human wellbeing. Enhancing the diversity of plant species in streetscapes would have a positive effect on wellbeing, further emphasising the important role that biodiverse urban streetscapes play in improving the liveability of cities.

Children’s exposure to BC and PM pollution, and respiratory tract deposits during commuting trips to school

Although children have been identified as a vulnerable group highly susceptible to traffic-related air pollution, their exposure during school commutes to traffic-related pollutants and the relevant health impact is rarely studied. In this study, we measured black carbon (BC) and particulate matter (PM: PM1, PM2.5, and PM10) concentrations that children are exposed to during their multi-modal (walking, private cars, and e-bikes) commuting trips to schools in Xi'an, China. A multi-parameter inhalation rate assessment model was developed in combination with the Multi-Path Particle Dosimetry (MPPD) model to quantify the deposition dose in different parts of children’s respiratory system (head, tracheobronchial (TB), pulmonary (PUL)). Results show that walking to school exposed children to the lowest PM1, PM2.5, and BC concentrations, whereas riding an e-bike led to significantly elevated exposure to PM1 and BC than the other two modes. This is due to children’s closer proximity to vehicle tail pipe emissions when they bike to school on road or roadside. The PM and BC concentrations showed remarkable increases in comparison to background concentrations during children’s school commutes. Urban background (UB) concentration, traffic volume (TV), time of day, and meteorological parameters could influence a child’s personal exposure, and the impact of each factor vary across different transportation modes. Particle size of the pollutant affects its deposition site in the respiratory system. Deposition fractions (DFs) and deposition doses in the head region (DF > 50%) were the highest for PM and BC, for which fine particles (BC, PM1, and PM2.5) were then most easily deposited in the PUL region while coarse particles rarely reach PUL. Children inhaled higher doses of polluted air during active commuting (walking) than passive commuting (private cars, e-bikes), due to longer times of exposure coupled with more active breathing.

Traffic pollution tracers in the lymphatic system tissue of children-possible link to chronic tonsillitis development: pilot study.

The origin of metal elements in tonsillar tissues of children patients was investigated in order to establish the link between environmental pollution and tonsilitis diagnosis. The children lived either in a polluted, industrial region (Moravian-Silesian Region, North-East Czechia) or a clean, predominantly agricultural region (South Bohemian Region, South-East Czechia). Simultaneously, the distance of the address of the patients to the closest main road was assessed. The elemental content of the present particulate matter in the tonsil samples, coming from indicated tonsillectomies, was analysed using scanning electron microscopy equipped with an X-ray microprobe. No significant association of the elemental composition and the region was found using both bivariate and multivariate methods; however, an association with the distance to the closest main road was found. The study presents a novel assessment of the tonsillar tissues and supports the link between environmental factors (traffic-related particulate pollution) and the onset of chronic, idiopathic diseases in children, which has been debated recently.

Comparison of exposure to traffic-related pollutants on different commuting routes to a primary school in Jinan, China.

Traffic-related pollutants seriously affect human health, and the commute time to and from school is the time when students are exposed greatest to traffic pollution sources. Field measurements were conducted with hand-held instruments while walking along two selected commuting routes in winter and spring. The measured data were then compared with background monitoring data, and the respiratory deposition dose (RDD) was calculated to assess the exposure risk. Particulate matter intake from 2018 to 2020 was calculated. In winter, the average concentrations of PM2.5 and PM10 were higher in the afternoon than in the morning. The highest concentration was 2.94 times greater than the background value. The low-concentration distribution area of the low-traffic route that is off the main road (route B) was more significant than that of the high-traffic route that is near the main road (route A). Moreover, the RDD of route B was consistently lower than that of route A, while the average annual amount of PM2.5 inhalation on route B in 3 years was 16.3% lower than that on route A. Overall, route B is more suitable than route A for students to commute on foot. Based on the findings, a walking route located within a community is a good choice.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-021-18362-w.

Cold Climate Impact on Air-Pollution-Related Health Outcomes: A Scoping Review.

In cold temperatures, vehicles idle more, have high cold-start emissions including greenhouse gases, and have less effective exhaust filtration systems, which can cause up to ten-fold more harmful vehicular emissions. Only a few vehicle technologies have been tested for emissions below −7 °C (20 °F). Four-hundred-million people living in cities with sub-zero temperatures may be impacted. We conducted a scoping review to identify the existing knowledge about air-pollution-related health outcomes in a cold climate, and pinpoint any research gaps. Of 1019 papers identified, 76 were selected for review. The papers described short-term health impacts associated with air pollutants. However, most papers removed the possible direct effect of temperature on pollution and health by adjusting for temperature. Only eight papers formally explored the modifying effect of temperatures. Five studies identified how extreme cold and warm temperatures aggravated mortality/morbidity associated with ozone, particles, and carbon-monoxide. The other three found no health associations with tested pollutants and temperature. Additionally, in most papers, emissions could not be attributed solely to traffic. In conclusion, evidence on the relationship between cold temperatures, traffic-related pollution, and related health outcomes is lacking. Therefore, targeted research is required to guide vehicle regulations, assess extreme weather-related risks in the context of climate change, and inform public health interventions.

Effects of Ambient Exposure to Nitrogen Dioxide on Outpatient Visits for Psoriasis in Rapidly Urbanizing Areas

Rapid development and urbanization can increase ambient exposure to NO2 and its health risks in individuals. However, the association between NO2 exposure and outpatient visits of patients with psoriasis has rarely been reported, though psoriasis is a major skin disease in rapidly urbanizing areas with high population densities. This study applied a time-stratified case-crossover design to investigate the effect of short-term exposure to ambient NO2 on outpatient visits for psoriasis from 2014 to 2020 in Guangzhou, China (n = 62,305). A subgroup analysis was performed to evaluate NO2 impacts on vulnerable subpopulations. Our results showed that the NO2 concentration during the study period was lower than that of the level II threshold from China (PRC) but higher than that set by the WHO, indicating moderate air quality. However, a 10-µg m-3 increase in NO2 concentration could still be associated with 3.1% higher outpatient visits for psoriasis (adjusted RR of lag 0 d:1.031 [CI:1.025, 1.037]). NO2 exposure can also pose long-term risks. Additionally, NO2 impacts on psoriasis may be independent of other pollutants. Adjusting for PM2.5, SO2, O3, and meteorological factors, a 10-µg m-3 increase in NO2 was associated with RRs of 1.043 [CI:1.033, 1.053], 1.022 [CI:1.014, 1.031], and 1.022 [CI:1.014, 1.031] at lag 0, lag 1, and lag 2 days, respectively. NO2 risks were higher among older individuals (age ≥ 60 years) and those with medical insurance [adjusted RRs: 1.045 (CI:1.023, 1.066) and 1.047 (CI:1.036, 1.058)]. Being a major pollutant in rapidly urbanizing areas with high population densities, NO2 emission could be a crucial factor in psoriasis, although the daily pollution level was not above the air quality thresholds. Challenges associated with air quality control and health disparity create a necessity for the enhancement of health and environmental policies to reduce local and regional emissions (e.g., traffic-related pollution), and vulnerable subpopulations should be targeted.

Research status and control measures of air pollutants in urban areas caused by traffic sources

With both the social and the economic development, air pollution has become a matter of high concern to both the public and the government. Vehicle exhaust emissions on traffic roads are the main source of urban air pollution in urban area, which poses a significant threat and impact on the health of urban residents. In order to solve the excessive urban pollutants in a better and more efficient way, reasonable and economic solutions should be investigated from the three aspects, including source identification, pollutant distribution and treatment measures. As for the distribution of pollutants in regional urban scale, this paper analyzes and summarizes the four influencing factors, including different urban layout schemes, meteorological conditions, roadside tree configurations and motor vehicle flows. The methods to study the distribution of air pollutants are summarized. Meanwhile, China has promulgated many standards and policies for the treatment of pollutants, which has achieved good results. To control urban pollutants from the root, it is necessary to look at the problem of urban pollutants from various aspects with appropriate methods, affordable human and material resources and reasonable relevant policies. This study provides a scientific support for control of traffic-related pollutants in urban area.

The Determination of Lead and Cadmium Concentration in the Agricultural Soils Alongside Highway 080 of Igdir Province

Gases emitted from both industrial estates and automobile exhausts in agricultural areas cause heavy metal pollution and these metals accumulate in the soil and plants. In this study, 72 soil samples were taken at 5 km intervals from 24 points along the Tuzluca-Iğdır-Nakhchivan route, through which the 080 State Road passes, at 0-10-30 meters perpendicularly inwards from the road and at a depth of 0-20 cm. Total lead (Pb) and cadmium (Cd) accumulations were determined in the samples. The significant decrease in lead and Cd concentrations away from the road indicates that heavy metal deposits have being caused by traffic. The effect of prevailing winds on total Pb and Cd deposition in north and south of the State Highway 080 was statistically insignificant. As the relationships between heavy metal concentrations and soil physical properties were considered, significant negative correlations were found between total Cd concentrations and sand and organic matter contents. Heavy metal pollution index (PI) values were found to be slightly and moderately polluted for Pb and close to highly polluted for Cd according to treshold values. The pollution load index (PLI) values were calculated as a function of the pollution index and according to the PLI results, it was evaluated that Pb and Cd triggered each other in terms of increasing toxic effects. It has been concluded that, with the re-establishment of the Silk Road, the traffic-related pollution will increase in the region.

Identifying trends in ultrafine particle infiltration and carbon dioxide ventilation in 92 vehicle models

There has been ongoing research aimed at reducing pollution concentrations in vehicles due to the high exposure which occurs in this setting. These studies have found using recirculate (RC) settings substantially reduces in-cabin traffic-related pollution concentrations but possibly leads to an adverse accumulation of carbon dioxide (CO2) from driver respiration. The aim of this study was to highlight how vehicle models and ventilation settings affect in-cabin concentrations to ultrafine particles (UFP) and CO2 in real-world conditions. We assessed the ability of different vehicles to balance reductions in UFP against the build-up of in-cabin CO2 concentrations by measuring these pollutants concurrently both inside and outside the vehicle to derive an in/out ratio.When ventilation settings were set to RC, UFP concentrations inside the vehicles (median: 3205 pt./cm3) were 86% lower compared to outside air (OA) (23,496 pt./cm3) across a 30-min real-world driving route. However, CO2 concentrations demonstrated a rapid linear increase under RC settings, at times exceeding 2500 ppm. These concentrations have previously been associated with decreased cognitive performance. Our study did not find an effect of gasoline fuelled vehicles affecting in-cabin UFP levels compared to hybrid or electric vehicles, suggesting that self-pollution was not an issue. We also found that certain vehicle models were better at reducing both in-cabin UFP and CO2 concentrations. The results suggest that under RC settings in/out CO2 ratios are largely determined by the leakiness of the vehicle cabin, whereas in/out UFP ratios are primarily determined by the efficacy of the in-built air filter in the vehicles ventilation system.

Proximity to Heavy Traffic Roads and Patient Characteristics of Late of Onset Asthma in an Urban Asthma Center

Background: Traffic-related pollution is associated with the onset of asthma and the development of different phenotypes of asthma. Few studies have investigated the association between traffic proximity and late-onset of asthma (LOA) and early-onset asthma (EOA). This study was conducted to investigate the associations of LOA phenotypes with a function of the distance between residence and heavy traffic roads (HTRs).Methods: The study group consisted of 280 patients who were (LOA: 78.4%) recruited consecutively from a pay-for-performance asthma program to clarify the patient characteristics and proximity to HTRs within 1,000 m from their residences between EOA and LOA in three urban centers in Taiwan. The subsequent analysis focused on patients with LOA (n = 210) linking phenotypes and distance to HTRs.Results: Subjects with LOA tended to be older than those with EOA and had shorter asthma duration, poorer lung function, lower atopy, and less exposure to fumes or dust at home. Patients with LOA were more likely than those with EOA to live within 900 m of two or more HTRs (14.3 vs. 3.4%, p = 0.02). Among patients with LOA, minimum distance to an HTR was negatively associated with numbers of specific IgE as well as positively associated with the age of onset and body weight significantly. A higher proportion of patients with atopy (26.3 vs. 20.6%, p = 0.001. odds ratio [OR]: 2.82) and anxiety/depression (21.0 vs. 18.1%, p = 0.047. OR: 1.81) and a trend of lower proportion of patients with obese (5.7 vs. 12.4%, p = 0.075) were found to be living within 900 m from HTRs.Conclusions: Late-onset of asthma (LOA) tended to live in areas of higher HTR density compared to EOAs. Among patients with LOA living close to HTRs, the interaction between traffic-related pollution, allergy sensitization, and mood status were the factors associated with asthma onset early. Obesity may be the factor for later onset who live far from HTRs.

Air pollution influence on serum inflammatory interleukins: A prospective study in childhood-onset systemic lupus erythematous patients.

To assess the effect of individual exposure, in real-time, to traffic-related pollutants on serum interleukin levels of childhood-onset lupus erythematous systemic (c-SLE) patients. A longitudinal and observational design was conducted in 12 repeated measures of serum samples and clinical evaluations (totaling 108 measurements) of c-SLE patients over 30 consecutive months. Real-time, individual exposure to fine particles (PM2.5) and nitrogen dioxide (NO2) was measured with portable monitors. Generalized estimating equation was used to evaluate the association between exposure to PM2.5 and NO2 and the following serum cytokine levels on the 7days preceding clinical assessment and serum collection: MCP1, IL-6, IL-8, IL-10, IL-17, IFN-alpha, and TNF-alpha. Disease activity and other risk factors were also controlled. An interquartile range (IQR) increase in PM2.5 daily concentration was significantly associated with increased levels of TNF-alpha on the third, fourth, and seventh day after exposure; IL-10 on the third and fourth day after exposure; IL-17 on the third and seventh day after exposure; and INF-alpha on the third day after exposure (p < 0.05). An IQR increase in 7-day moving average of PM2.5 was associated with a 6.2pg/mL (95% CI: 0.5; 11.8; p = 0.04) increase in serum IFN-alpha level. An unexpected significant association was observed between an IQR increase in NO27-day cumulative concentration and a decrease of 1.6pg/mL (95% CI: -2.6; -0.7; p < 0.001) in serum IL-17. Real-time exposure to PM2.5 prospectively associated with increased serum TNF-alpha, INF-alpha, IL-10, and IL-17 levels in c-SLE patients.

Identifying low-PM2.5 exposure commuting routes for cyclists through modeling with the random forest algorithm based on low-cost sensor measurements in three Asian cities

Cyclists can be easily exposed to traffic-related pollutants due to riding on or close to the road during commuting in cities. PM2.5 has been identified as one of the major pollutants emitted by vehicles and associated with cardiopulmonary and respiratory diseases. As routing has been suggested to reduce the exposures for cyclists, in this study, PM2.5 was monitored with low-cost sensors during commuting periods to develop models for identifying low exposure routes in three Asian cities: Taipei, Osaka, and Seoul. The models for mapping the PM2.5 in the cities were developed by employing the random forest algorithm in a two-stage modeling approach. The land use features to explain spatial variation of PM2.5 were obtained from the open-source land use database, OpenStreetMap. The total length of the monitoring routes ranged from 101.36 to 148.22 km and the average PM2.5 ranged from 13.51 to 15.40 μg/m³ among the cities. The two-stage models had the standard k-fold cross-validation (CV) R2 of 0.93, 0.74, and 0.84 in Taipei, Osaka, and Seoul, respectively. To address spatial autocorrelation, a spatial cross-validation approach applying a distance restriction of 100 m between the model training and testing data was employed. The over-optimistic estimates on the predictions were thus prevented, showing model CV-R2 of 0.91, 0.67, and 0.78 respectively in Taipei, Osaka, and Seoul. The comparisons between the shortest-distance and lowest-exposure routes showed that the largest percentage of reduced averaged PM2.5 exposure could reach 32.1% with the distance increases by 37.8%. Given the findings in this study, routing behavior should be encouraged. With the daily commuting trips expanded, the cumulative effect may become significant on the chronic exposures over time. Therefore, a route planning tool for reducing the exposures shall be developed and promoted to the public.