M. Lopes

Procedures for estimation of modelling uncertainty in air quality assessment

The main objectives of this work focus, firstly, on a review of the current existent methodologies to estimate air quality modelling uncertainty, and, secondly, in the preparation of guidelines for modelling uncertainty estimation, which can be used by local and regional authorities responsible for air quality management. From the application exercise, it was concluded that it is possible to define a subset of statistical parameters able to reproduce the general uncertainties estimation. Concerning the quality indicators defined by EU directives, the results show that the legislated uncertainty estimation measures are ambiguous and inadequate in several aspects, mainly in what concerns the error measures for hourly and daily indicators based on the highest observed concentration. A relative error at the percentile correspondent to the allowed number of exceedances of the limit value was suggested and tested, showing that is a more robust and appropriate parameter for model performance evaluation.

Airways changes related to air pollution exposure in wheezing children

In this study, we aimed to evaluate the relationship between individual total exposure to air pollution and airway changes in a group of 51 wheezing children. Respiratory status was assessed four times (January 2006, June 2006, January 2007 and June 2007) during a 1-week period through a standardised questionnaire, spirometry, exhaled nitric oxide fraction and pH in exhaled breath condensate (EBC). Concentrations of particles with a 50% cut-off aerodynamic diameter of 10 µm (PM10), O3, NO2 and volatile organic compounds were estimated through direct measurements with an ad hoc device or air pollution modelling in the childrens schools and at their homes in the same 4 weeks of the study. For each child, total exposure to the different air pollutants was estimated as a function of pollutant concentrations and daily activity patterns. Increasing total exposure to PM10, NO2, benzene, toluene and ethylbenzene was significantly associated with a decrease of forced expiratory volume in 1 s (FEV1) and with an increase of change in FEV1. Increasing exposure to NO2 and benzene was also related to a significant decrease of FEV1/forced vital capacity. Increasing exposure to PM10, NO2, benzene and ethylbenzene was associated with acidity of EBC. This study suggests an association in wheezing children between airway changes and total exposure to air pollutants, as estimated by taking into account the concentration in the various microenvironments attended by the children.

Air pollution forecast in Portugal : a demand from the new air quality framework directive

This work aims at developing and validating a numerical air quality operational forecasting system that will be applied over Portugal. The CHIMERE model was chosen for the chemistry-transport simulation using the meteorological parameters supplied by the MM5 mesoscale meteorological model, forced by the AVN/NCEP global forecasts. An experiment of 48-hour real-time forecast simulations was performed, on a daily basis, during the four summer months of 2003. The numerical model system is then evaluated against hourly time series of basic meteorological variables and of ozone and NO2 concentrations, collected in several Portuguese monitoring stations included in meteorological and air quality network. Statistical skill scores are discussed and compared with previous studies. The results point this developed model system as a useful tool that can be used and implemented to anticipate pollution episodes, to local and regional air quality management and for population information purpose.

Local-scale modelling system to simulate smoke dispersion

The main purpose of this paper is to present a fire behaviour system, developed to estimate fire progression, smoke dispersion and visibility impairment, at a local scale, and to evaluate its performance by comparing results with measurements from the Gestosa 2004 experimental field fires. The system is an improvement of two already available numerical tools, DISPERFIRE (Miranda et al. 1994) and FireStation (Lopes et al. 2002), which were integrated. FireStation is a software system aimed at the simulation of fire spread over complex topography. DISPERFIRE is a real-time system developed to simulate the dispersion in the atmosphere of the pollutants emitted during a forest fire. In addition, a model for the estimation of visibility impairment, based on the relationship between air pollutants concentration and visibility, was included in DISPERFIRE. The whole system was developed using a graphical interface, previously created for FireStation, which provides user-friendliness and easily readable output to facilitate its application under operational conditions. The system was applied to an experimental field fire and the main results were compared with experimental air pollutant concentration measured values. The performance of the model in predicting pollutant concentrations was good, particularly for NO2 and PM10.

Impact of forest biomass residues to the energy supply chain on regional air quality.

The increase of the share of renewable energy in Portugal can be met from different sources, of which forest biomass residues (FBR) can play a main role. Taking into account the demand for information about the strategy of FBR to energy, and its implications on the Portuguese climate policy, the impact of energy conversion of FBR on air quality is evaluated. Three emission scenarios were defined and a numerical air quality model was selected to perform this evaluation. The results reveal that the biomass thermal plants contribute to an increment of the pollutant concentrations in the atmosphere, however restricted to the surrounding areas of the thermal plants, and most significant for NO₂ and O₃.

Air quality assessment of Estarreja, an urban industrialized area, in a coastal region of Portugal

Despite the increasing concern given to air quality in urban and industrial areas in recent years, particular emphasis on regulation, control, and reduction of air pollutant emissions is still necessary to fully characterize the chain emissions–air quality–exposure–dose–health effects, for specific sources. The Estarreja region was selected as a case study because it has one of the largest chemical industrial complexes in Portugal that has been recently expanded, together with a growing urban area with an interesting location in the Portuguese coastland and crossed by important road traffic and rail national networks. This work presents the first air quality assessment for the region concerning pollutant emissions and meteorological and air quality monitoring data analysis, over the period 2000–2009. This assessment also includes a detailed investigation and characterization of past air pollution episodes for the most problematic pollutants: ozone and PM10. The contribution of different emission sources and meteorological conditions to these episodes is investigated. The stagnant meteorological conditions associated with local emissions, namely industrial activity and road traffic, are the major contributors to the air quality degradation over the study region. A set of measures to improve air quality—regarding ozone and PM10 levels—is proposed as an air quality management strategy for the study region.

Assessment of health benefits related to air quality improvement strategies in urban areas: An Impact Pathway Approach

Air pollution is, increasingly, a concern to our society given the threats to human health and the environment. Concerted actions to improve air quality have been taken at different levels, such as through the development of Air Quality Plans (AQPs). However, air quality impacts associated with the implementation of abatement measures included in AQPs are often neglected. In order to identify the major gaps and strengths in current knowledge, a literature review has been performed on existing methodologies to estimate air pollution-related health impacts and subsequent external costs. Based on this review, the Impact Pathway Approach was adopted and applied within the context of the MAPLIA research project to assess the health impacts and benefits (or avoided external costs) derived from improvements in air quality. Seven emission abatement scenarios, based on individual and combined abatement measures, were tested for the major activity sectors (traffic, residential and industrial combustion and production processes) of a Portuguese urban area (Grande Porto) with severe particular matter (PM10) air pollution problems. Results revealed a strong positive correlation between population density and health benefits obtained from the assessed reduction scenarios. As a consequence, potential health benefits from reduction scenarios are largest in densely populated areas with high anthropic activity and, thus, where air pollution problems are most alarming. Implementation of all measures resulted in a reduction in PM10 emissions by almost 8%, improving air quality by about 1% and contributing to a benefit of 8.8 million €/year for the entire study domain. The introduction of PM10 reduction technologies in industrial units was the most beneficial abatement measure. This study intends to contribute to policy support for decision-making on air quality management.

Influence of urban resilience measures in the magnitude and behaviour of energy fluxes in the city of Porto (Portugal) under a climate change scenario

Different urban resilience measures, such as the increase of urban green areas and the application of white roofs, were evaluated with the WRF-SUEWS modelling system. The case study consists of five heat waves occurring in Porto (Portugal) urban area in a future climate scenario. Meteorological forcing and boundary data were downscaled for Porto urban area from the CMIP5 earth system model MPI-ESM, for the Representative Concentration Pathway RCP8.5 scenario. The influence of different resilience measures on the energy balance components was quantified and compared between each other. Results show that the inclusion of green urban areas increases the evaporation and the availability of surface moisture, redirecting the energy to the form of latent heat flux (maximum increase of +200Wm(-2)) rather than to sensible heat. The application of white roofs increases the solar radiation reflection, due to the higher albedo of such surfaces, reducing both sensible and storage heat flux (maximum reductions of -62.8 and -35Wm(-2), respectively). The conjugations of the individual benefits related to each resilience measure shows that this measure is the most effective one in terms of improving the thermal comfort of the urban population, particularly due to the reduction of both sensible and storage heat flux. The obtained results contribute to the knowledge of the surface-atmosphere exchanges and can be of great importance for stakeholders and decision-makers.

Air quality modelling as a supplementary assessment method in the framework of the European Air Quality Directive

According to the European Air Quality (AQ) Directive, member states must annually report their AQ to the European Commission (EC). This report can be based on modelling data if the concentration levels do not exceed the established lower assessment thresholds (LAT), or on combined data from modelling and monitoring systems (supplementary assessment methods) if concentrations levels are below the upper assessment threshold (UAT). This work presents and applies a methodology that combines air pollutant concentration values from monitored data and from a numerical modelling system to deliver AQ information for Portugal in 2010. This methodology produces improved information, especially for areas where the amount of fixed monitoring stations is sparse or non-existent, allowing obtaining a better and broader overview of the AQ in Portugal to support AQ reporting to the European Commission.

Impact of urban planning alternatives on air quality: URBAIR model application

In the last decades, the study of the urban structure impacts on the quality of life and on the environment became a key issue for urban sustainability. Nowadays the relevance of urban planning for the improvement of the interactions between different land uses and economic activities, and also towards a more sustainable urban metabolism, is consensually accepted. A major interest relies on understanding the role of planning on induced mobility patterns and thereafter on air quality, particularly related with the increasing use of private cars. This is one of the main objectives of BRIDGE, a research project funding by the European Commission under the 7 th Framework Programme and focused on “SustainaBle uRban plannIng Decision support accountinG for urban mEtabolism”. In this scope, and to evaluate the impact on air quality due to different city planning alternatives (PA), the urban scale air quality modelling system URBAIR was applied to selected areas in Helsinki (Finland), Athens (Greece) and Gliwice (Poland), to estimate traffic related emissions and induced pollutant concentration of different air pollutants, in a hourly basis for the entire year of 2008. For the Helsinki study case the results suggest that urban traffic and building placement considered on the different PA have an influence on local air quality despite no significant concentration levels. In the Athens case study some PA induce a decrease on traffic flows with an improvement of the air quality over the domain. On the contrary, other leads to an increase of PM10 in selected hotspots. The simulations for the Gliwice study case show minor changes between the baseline and the PA, since the proposed interventions do not imply major changes in traffic flows.