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Publications

Publications by Tânia Daniela Fontes

2014

Learning from 24 years of ozone data in Portugal

Authors
Barros, N; Silva, MP; Fontes, T; Manso, MC; Carvalho, AC;

Publication
WIT Transactions on Ecology and the Environment

Abstract
Ozone (O3) is a secondary pollutant mainly produced in the troposphere by photochemical reactions with high impact on human health. In this work hourly average O3 concentrations from the Portuguese air quality network collected during 24 years (1988–2011) were analysed. The background time series were assessed by environment type (urban, suburban and rural) and considering several criteria: the annual mean O3 concentration, the Directive 2008/50/EC O3 long-term objective and the 2005 WHO Guideline for protection of human health and, finally, the hourly information threshold exceedances. The trend of annual mean O3 concentration data and the maximum daily eight-hour mean ozone concentration data were both annually compared using an one-way ANOVA followed by a Tamhane post-hoc comparison test. In both series, although of an instable trend, a tendency for an increase of the mean O3 concentrations was found. On the other hand, after 2006, for all stations types, the normalized number of exceedances for public O3 information are significantly decreasing (p<0.05). In this paper, the O3 trend will be analyzed and discussed, contributing to improve knowledge of long time series of O3 concentrations in Portugal. © 2014 WIT Press.

2015

Multicriteria Assessment of Crosswalk Location in Urban Roundabout Corridors

Authors
Fernandes, P; Fontes, T; Pereira, SR; Rouphail, NM; Coelho, MC;

Publication
TRANSPORTATION RESEARCH RECORD

Abstract
Midblock pedestrian crossing areas between closely spaced roundabouts can affect traffic operations and may result in a trade-off between capacity, environment, and safety benefits. Even though research has been conducted on the impacts of traffic performance on pedestrian crosswalks located at isolated roundabouts, few studies have focused on how pedestrian crosswalks between closely adjacent roundabouts affect traffic operations. A microsimulation approach was used to examine the integrated effect of a pedestrian crosswalk on traffic delay, carbon dioxide emissions, and relative speed between vehicles and pedestrians at different locations between closely spaced two-lane roundabouts. The main purpose of the study was to develop a simulation platform of traffic (VISSIM), emissions (vehicle-specific power), and safety (surrogate safety assessment model) to optimize such variables. The fast nondominated sorting genetic algorithm NSGA-II was mobilized to identify an optimized set of pedestrian crosswalk locations for the roundabout exit section along the midblock segment. One acceptable solution that provided a good balance between traffic performance, emissions, and pedestrian safety benefits was locating the crosswalks at 15, 20, and 30 m from the exit section. Even at low pedestrian demand, crosswalk effectiveness (as determined by capacity and environment) gradually decreased near the circulatory ring delimitation (<10 m). Findings suggest that crosswalks in the midblock segment (55 to 60 m from the exit section) also must be considered, especially under high traffic demand.

2018

A proposed methodology for impact assessment of air quality traffic-related measures: The case of PM2.5 in Beijing

Authors
Fontes, T; Li, PL; Barros, N; Zhao, PJ;

Publication
ENVIRONMENTAL POLLUTION

Abstract
Air quality traffic-related measures have been implemented worldwide to control the pollution levels of urban areas. Although some of those measures are claiming environmental improvements, few studies have checked their real impact. In fact, quantitative estimates are often focused on reducing emissions, rather than on evaluating the actual measures' effect on air quality. Even when air quality studies are conducted, results are frequently unclear. In order to properly assess the real impact on air quality of traffic-related measures, a statistical method is proposed. The method compares the pollutant concentration levels observed after the implementation of a measure with the concentration values of the previous year. Short- and long-term impact is assessed considering not only their influence on the average pollutant concentration, but also on its maximum level. To control the effect of the main confounding factors, only the days with similar environmental conditions are analysed. The changeability of the key meteorological variables that affect the transport and dispersion of the pollutant studied are used to identify and group the days categorized as similar. Resemblance of the pollutants' concentration of the previous day is also taken into account. The impact of the road traffic measures on the air pollutants' concentration is then checked for those similar days using specific statistical functions. To evaluate the proposed method, the impact on PM2.5 concentrations of two air quality traffic-related measures (M1 and M2) implemented in the city of Beijing are taken into consideration: M1 was implemented in 2009, restricting the circulation of yellow-labelled vehicles, while M2 was implemented in 2014, restricting the circulation of heavy-duty vehicles. To compare the results of each measure, a time-period when these measures were not applied is used as case-control.

2019

Environmental and biological monitoring of benzene, toluene, ethylbenzene and xylene (BTEX) exposure in residents living near gas stations

Authors
Barros, N; Carvalho, M; Silva, C; Fontes, T; Prata, JC; Sousa, A; Manso, MC;

Publication
JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH-PART A-CURRENT ISSUES

Abstract
The volatile organic compounds benzene, toluene, ethylbenzene, and xylene (BTEX) are emitted into the atmosphere at gas stations (GS) leading to chronic exposure of nearby residents, which raises public health concerns. This study aimes at determining the contribution of GS emissions to BTEX exposure in nearby residents. Three Control and Exposed areas to BTEX emissions from GS were defined in a medium-sized European city (Porto, Portugal). BTEX atmospheric levels were determined in Control and Exposed areas using passive samplers deployed outdoors (n = 48) and indoors (n = 36), and human exposure was estimated for 119 non-smoking residents using the first urine of the day. Results showed that median BTEX outdoor and indoor concentrations were significantly higher for Exposed than Control areas, with exception of ethylbenzene and xylene indoor concentrations, where no marked differences were found. Comparison of urinary concentrations between Exposed and Control residents demonstrated no significant differences for benzene and ethylbenzene, whereas levels of toluene and xylene were significantly higher in Exposed residents. No marked correlation was obtained between atmospheric BTEX concentrations and urinary concentrations. Data indicate the potential impact on air quality of BTEX emissions from GS, which confirms the importance of these findings in urban planning in order to minimize the impact on health and well-being of surrounding populations.

2019

Exposure to BTEX in buses: The influence of vehicle fuel type

Authors
Fontes, T; Manso, MC; Prata, JC; Carvalho, M; Silva, C; Barros, N;

Publication
ENVIRONMENTAL POLLUTION

Abstract
Diesel-fueled buses have been replaced by Compressed Natural Gas (CNG) to minimize the high level of emissions in urban areas. However, differences in indoor exposure levels to Benzene, Toluene, Ethylbenzene and Xylene (BTEX) in those vehicles have not been investigated so far. The primary aim of this study was to determine if passengers are exposed to different BTEX levels when using buses powered by CNG or by diesel, and further explore if indoor levels are influenced by external air quality. For this purpose, BTEX air concentrations were measured in bus cabins (CNG and diesel), parking stations and in a background urban area using passive air samplers. Results showed that BTEX concentrations inside vehicles were higher than outside, but no significant differences were found between buses powered by CNG or by diesel. In CNG vehicles, high and significant positive correlation was found between benzene and the number of journeys in the same route (r(s) = 0.786, p < 0.05), vehicle operating time (r(s) = 0.738, p < 0.05), exposure time (r(s) = 0.714, p < 0.05) and exposure index (r(s) = 0.738, p < 0.05), but this was not observed for diesel vehicles. Benzene in bus cabins was found to be significantly below reference value for human health protection. However, excepting p-xylene, all other aromatic pollutants have a mean concentration significantly above the lowest effect level (p <= 0.002 for all comparisons). Additionally, higher BTEX levels in cabin buses than in outdoor air suggest the presence of other emission sources in indoor cabins. These findings emphasize the need for further studies to fully characterize indoor emission sources in order to minimize the negative impact of BTEX exposure to human health.

2020

Design of a Route-Planner for Urban Public Transport, Promoting Social Inclusion

Authors
Dias, R; Fontes, T; Galvao, T;

Publication
INTELLIGENT TRANSPORT SYSTEMS

Abstract
People that do not have access to the transport system and therefore, a facilitated access to goods and services essential to daily life, can be regarded as transport-related social excluded. This is a big issue, namely for groups of people that have physical, sensorial and/or cognitive limitations. This paper provides guidelines to design route planners for socially excluded groups, by promoting social inclusion in public transportation. For this purpose, a set of mock-up user-interfaces of an inclusive inter-modal route planning application were developed. These interfaces will deliver ready availability of information about infrastructures and other journey related data.

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