Traffic air quality index

Deployment of a mobile platform to characterize spatial and temporal variation of on-road fine particles in an urban area

Traffic-related air pollutants (TRAPs) pose a serious health hazard for residents and commuters in urban areas. In this study, a real-time mobile monitoring system was deployed in Taipei, a typical East Asian city with an overlap of high population density, traffic, and special structures (e.g., viaducts), to capture the on-road TRAPs at different times of the day. In general, black carbon, ultrafine particles (UFPs), CO concentrations, and lung deposition surface area (LDSA) were positively correlated with traffic flow, and for PM_2.5, a more independent fluctuating concentration was observed. During rush-hour periods, the mean concentrations of UFPs, PM_2.5, and LDSA were 6.12 × 10⁴ ± 3.83 × 10⁴ cm^-3, 23 ± 8 μg/m³, and 2.29 × 10² ± 1.20 × 10² μm²/cm³, respectively. Additionally, the UFP number concentration and LDSA were two times higher along the high-traffic commuting route than along the lower traffic route. Pollutants tended to accumulate at sites near viaducts and high buildings and were significantly influenced by vehicle composition. In this study, the ratio of LDSA to total particle surface area concentration was used as an indicator of the degree of particle irregularity, which was directly related to aging during transport.

Cost and Environmental Impacts of a Mixed Fleet of Vehicles

Urban parcel delivery is increasingly restricted by regulations limiting access to certain heavy or high emitting vehicles to reduce emissions and noise pollution in cities. Cargo bikes represent an alternative solution that enables deliveries with low environmental impact, but they may represent a higher economic cost and come with constraints like battery autonomy or small loading capacity. As a transport scheme relying on bikes for the last miles with fewer externalities, it is regarded as an environmentally friendly choice, and economic sustainability is assessed. This paper aims to present the environmental and economic aspects of different delivery means of transport in European urban areas. Life cycle assessment (LCA) methodology is selected to analyse the environmental impact of several vehicles, allowing us to quantify the emissions according to the loading factor. The electricity mix is an important parameter and makes the results vary according to the country studied. For the economic aspect, the cost price allows us to quantify the operational cost of each means of transport. A trade-off can thus be made between the two.

Influence of the seasonality and of urban variables in the BTEX and PM2.5 atmospheric levels and risks to human health in a tropical coastal city (Fortaleza, CE, Brazil)

The International Agency for Research on Cancer (IARC) classifies benzene in group 1 (carcinogenic to humans). Particulate matter (PM) has recently also been classified in this category. This was an advance toward prioritizing the monitoring of particles in urban areas. The aim of the present study was to assess levels of PM_2.5 and BTEX (benzene, toluene, ethylbenzene, and xylene), the influence of meteorological variables, the planetary boundary layer (PBL), and urban variables as well as risks to human health in the city of Fortaleza, Brazil, in the wet and dry periods. BTEX compounds were sampled using the 1501 method of NIOSH and determined by GC-HS-PID/FID. PM_2.5 was monitored using an air sampling pump with a filter holder and determined by the gravimetric method. Average concentrations of BTEX ranged from 1.6 to 45.5 μg m^-3, with higher values in the wet period, which may be explained by the fact that annual distribution is influenced by meteorological variables and the PBL. PM_2.5 levels ranged from 4.12 to 33.0 μg m^-3 and 4.18 to 86.58 μg m^-3 in the dry and wet periods, respectively. No seasonal pattern was found for PM_2.5, probably due to the influence of meteorological variables, the PBL, and urban variables. Cancer risk ranged from 2.46E^-04 to 4.71E^-03 and 1.72E^-04 to 2.01E^-03 for benzene and from 3.07E^-06 to 7.04E^-05 and 3.08E^-06 to 2.85E^-05 for PM_2.5 in the wet and dry periods, respectively. Cancer risk values for benzene were above the acceptable limit established by the international regulatory agency in both the dry and wet periods. The results obtained of the noncarcinogenic risks for the compounds toluene, ethylbenzene, and xylene were within the limits of acceptability. The findings also showed that the risk related to PM is always greater among smokers than nonsmokers.

The Challenges of Prolonged Gas Sensing in the Modern Urban Environment

The increase in the urban population is impacting the environment in several ways, including air pollution due to emissions from automobiles and industry. The reduction of air pollution requires reliable and detailed information regarding air pollution levels. Broad deployment of sensors can provide such information that, in turn, can be used for the establishment of mitigating and regulating acts. However, a prerequisite of such a deployment strategy is using highly durable sensors. The sensors must be able to operate for long periods of time under severe conditions such as high humidity, solar radiation, and dust. In recent years, there has been an ongoing effort to ruggedize sensors for industrial applications with an emphasis on elevated temperature, humidity, and pressure. Some of these developments are adapted for urban air sensing applications. However, protection from dust is based on filters that have not been modified in the last few decades. Such filters clog over time, thus requiring frequent replacement. This editorial presents the need for a consumable-free dust removal device that provides consistent performance without affecting the sensing process. A specific solution for removing dust using a cyclone dust separator is presented. The cyclone dust separator is implemented as an add-on module to protect commercially available sensors.

Anthropogenic or non-anthropogenic particulate matter: Which one is more dangerous and how to differentiate between the effects?

The authors have observed that the function linking health outcomes with exposure to particulate-matter (PM) follows a biphasic pattern. It peaks around levels of PM10≤100 μg/m3, then weakens and rises again at PM10 levels in the range of hundreds. This could be due to a different nature of PM, the first peak reflecting a stronger anthropogenic and the second - weaker non-anthropogenic particles' effect. The current analysis is focused at the biphasic pattern on the association between PM levels with BG and asthma exacerbations. Pollutants were assessed by local monitoring stations and a satellitebased model. Local weekends/holidays were used to define nonanthropogenic levels of pollutants featured by lower Nitrogen Dioxide, the proxy for anthropogeneity. The association of PM₁₀ with health outcomes within 24-48h lag was explored using spline functions of generalized additive models. Analysis of 546,420 BG tests (43,569 subjects) showed an almost linear association of PM₁₀ with asthma with BG during the days with anthropogenic activity and no trend on other days. Analysis of asthmatic exacerbations within 1576 children showed no heterogeneity in association with PM₁₀ by anthropogeneity levels, possibly indicating a mechanical impact on alveolar as the main trigger for exacerbations rather than PM₁₀ chemical composition.

Socioeconomic factors increase the adverse effects of air pollution and temperature on mortality

OBJECTIVE

To verify the effects of PM2.5 and temperature on mortality due to cardiovascular diseases according to socioeconomic status and traffic proximity.

METHOD

Time series were used, using the generalized additive models with the Poisson regression option, at 5% significance level. Interactionbetween proximity of traffic and socioeconomic status was analyzed through stratification. The proximity to the traffic was divided into distances up to 150m or over 150m. Socioeconomic status in the residential environment was categorized as high and low based on the median (3.9%). The relative risk percentage (%RR) of cardiovascular disease deaths was calculated for each linear increase of 10 µg/m3 at PM2.5 and 1ºC at the maximum temperature.

RESULTS

Mortality due to cardiovascular diseases presented %RR 1.64 (95%CI -0.03; 3.33), related to the maximum temperature and %RR 4.60 (95%CI 0.78; 8.56) related to PM2.5, in areas with high traffic exposure. In areas with poor living conditions, %RR 1.34 (95%CI -0.31; 3.01) was observed, related to maximum temperature and RR% 3.95 (95%CI -0.27; 8.34) associated with PM2.5.

CONCLUSION

Areas with poor living conditions and high-exposure to vehicular traffic had an increased risk of cardiovascular disease mortality related to high temperature and PM2.5.

The aggravation of urban air quality deterioration due to urbanization, transportation and economic development - Panel models with marginal effect analyses across China

In this paper, panel data models are established to examine the impacts of urban construction, transport facilities, and economic development on the urban air quality. Combined with data from different tiers of Chinese cities for two time series, 2010 and 2015, the variable-intercept model (VIM) is used to determine the parameters and significance of each independent variable. The marginal effects of different categories of independent variables (urbanization, transportation and economy) on the urban air quality are also studied with regard to the results of different VIMs. The results show that transportation factors (such as annual passenger trips, bus numbers and taxi numbers) have the most significant effects on the air quality for all the Chinese cities. Moreover, urbanized area and annual gross value of industrial output also have prominent impacts on the air quality across China. In addition, the marginal effects of the air quality index obtained via VIMs with classified local variables reflect that the influences of urbanization, transportation and economy on urban air quality are substantially different among different tiers of cities. Therefore, based on the findings, we propose measures to improve air quality for different tiers of cities, such as rational use of space resources, optimizing transport modes, and encouraging carpooling.

Relationship between rooftop and on-road concentrations of traffic-related pollutants in a busy street canyon: Ambient wind effects

Rooftop and on-road measurements of O3, NO2, NOx, and CO concentrations were conducted to investigate the relationship between rooftop and on-road concentrations in a busy and shallow street canyon with an aspect ratio of ∼0.3 in Seoul, Republic of Korea, from 15 April to 1 May 2014. The median road-to-roof concentration ratios, correlation coefficients between rooftop and on-road concentrations, and temporal variations of rooftop and on-road concentrations are analyzed according to the rooftop wind directions which are two cross-canyon and two along-canyon directions. The analysis results indicate that the relationship is strong when the rooftop is situated on the downwind side rather than on the upwind side. Relative to the cross-canyon wind directions, one of the along-canyon wind directions can more enhance the relationship. A conceptual framework is proposed to explain the effect of ambient wind direction on the relationship between rooftop and on-road concentrations in a street canyon.