Impact of vehicular traffic emissions on particulate-bound PAHs: levels and associated health risks

Considering vehicular transport as one of the most health���relevant emission sources of urban air, and with aim to further understand its negative impact on human health, the objective of this work was to study its influence on levels of particulate���bound PAHs and to evaluate associated health risks. The 16 PAHs considered by USEPA as priority pollutants, and dibenzo[a, l]pyrene associated with fine (PM2.5) and coarse (PM2.5���10) particles were determined. The samples were collected at one urban site, as well as at a reference place for comparison. The results showed that the air of the urban site was more seriously polluted than at the reference one, with total concentrations of 17 PAHs being 2240% and 640% higher for PM2.5 and PM2.5���10, respectively; vehicular traffic was the major emission source at the urban site. PAHs were predominantly associated with PM2.5 (83% to 94% of ��PAHs at urban and reference site, respectively) with 5 rings PAHs being the most abundant groups of compounds at both sites. The risks associated with exposure to particulate PAHs were evaluated using the TEF approach. The estimated value of lifetime lung cancer risks exceeded the health���based guideline levels, thus demonstrating that exposure to PM2.5���bound PAHs at levels found at urban site might cause potential health risks. Furthermore, the results showed that evaluation of benzo[a] pyrene (regarded as a marker of the genotoxic and carcinogenic PAHs) alone would probably underestimate the carcinogenic potential of the studied PAH mixtures.

Forest fires in Northern region of Portugal: impact on PM levels

Every year European citizens become victims of devastating fires, which are especially disastrous for Southern European countries. Apart from the numerous health and economic consequences, fires generate hazardous pollutants that are introduced into the environment, thus representing serious risks for public health. In that regard, particulate matter (PM) is of amajor concern. Thus, the objectives of thisworkwere to characterize the trend of forest fire occurrences and burnt area during the period of 2005 and 2010 and to study the influence of forest fires on levels of particulatematter PM10 and PM2.5. In 2010, 22,026 forest fires occurred in Portugal. The northern region was the most affected by forest fires, with 27% of occurrences in Oporto district. The annual means of PM10 and PM2.5 concentrations at two urban background sites were 25��14 ��g m���3 and 8.2��4.9 ��g m���3, and 17��13 ��g m���3 and 7.3��5.9 ��g m���3, respectively. At both sites the highest levels of PMfractionswere observed during July and August of 2010, corresponding to the periods when majority (66%) of forest fires occurred. Furthermore, PM10 daily limit at the two sites was exceeded during 20 and 5 days, respectively; 56%, and respectively 60% of those exceedances occurred during the forest fire season. Considering that the risks of forest fire ignition and severity are enhanced with elevated temperatures, the climate change might increase the environmental impacts of forest fires.

Exposi����o ocupacional a compostos org��nicos vol��teis e a mat��ria particulada na limpeza autom��vel em parques de estacionamento

Mestrado em Seguran��a e Higiene no Trabalho

Avalia����o da qualidade do ar interior em edif��cios do ISEP

Mestrado em Engenharia Qu��mica - Ramo Tecnologias de Protec����o Ambiental

Auditoria �� qualidade do ar interior de um edif��cio de servi��os - RSECE QAI

O objectivo principal deste trabalho �� a realiza����o de uma auditoria, �� qualidade do ar interior (QAI), a um edif��cio de servi��os ��� COCIGA, SA, tendo como base o Regulamento dos Sistemas Energ��ticos de Climatiza����o dos Edif��cios (RSECE). A auditoria QAI implica a medi����o de v��rios par��metros f��sicos, qu��micos, microbiol��gicos e tamb��m a inspec����o aos componentes do sistema de climatiza����o com a finalidade de averiguar o seu estado de limpeza e manuten����o. Assim, foram seleccionados 3 espa��os, para a realiza����o de amostragens designados por Comercial - Produtos, AVAC e Mezaninne das oficinas, nos quais foi efectuada a medi����o de diversos par��metros, de acordo com as imposi����es do RSECE, utilizando medidores port��teis ou recorrendo a m��todos anal��ticos. Relativamente aos par��metros f��sicos, registaram-se valores de temperatura, para os tr��s espa��os estudados, entre os 21 e os 24 ��C e valores m��dios de humidade relativa de cerca de 50 %. Outro par��metro medido, e de grande import��ncia para garantir o conforto dos ocupantes, foi a velocidade do ar nos postos de trabalho. De acordo com o RSECE este valor n��o deve ser superior a 0,2 m/s, o que se verificou em todos os pontos medidos. O ��ltimo par��metro f��sico medido foi a concentra����o de part��culas (PM10) tendo-se obtido valores de cerca de 23 ��g/m3ar, valor bastante inferior ao m��ximo permitido pelo RSECE (150 ��g/m3ar). Tamb��m no que diz respeito aos par��metros qu��micos, ou seja, CO2, CO, formalde��do e ozono, n��o se verificaram valores superiores aos regulamentares. No caso do CO2, o valor m��ximo encontrado, nestes tr��s espa��os, foi de 745 ppm na Mezaninne das Oficinas e para o CO, na zona AVAC com uma concentra����o de 0,73 ppm. A medi����o do formalde��do registou valores perto dos 45 ��g/m3ar e o ozono apenas foi detectado, em concentra����o muito reduzida, na zona Comercial ��� Produtos. Por fim, as concentra����es de bact��rias e fungos, de acordo com o RSECE, n��o devem ultrapassar as 500 UFC/m3ar (par��metros microbiol��gicos). Em qualquer dos espa��os, os valores medidos foram inferiores ao m��ximo legal, n��o ultrapassando as 50 UFC/m3ar. Da avalia����o do projecto AVAC, e atrav��s da medi����o dos caudais de insufla����o/ extrac����o em cada zona, concluiu-se que os seus valores n��o est��o de acordo com os valores do projecto inicial que poder�� ser imputada a uma insufici��ncia no funcionamento do sistema detectada na altura das medi����es. No que diz respeito ao estado de limpeza do sistema AVAC, apenas foi poss��vel inspeccionar as unidades de tratamento de ar, tendo-se constatado que se encontram em boas condi����es. Ou seja, do ponto de vista do RSECE, e referindo-nos apenas �� vertente da Qualidade do Ar Interior, o edif��cio em causa, cumpre todos os limites impostos para as concentra����es de poluentes mas, apresenta algumas defici��ncias no que respeita aos caudais de ar novo insuflados em cada espa��o.

Project, modelling and simulation of air stripping columns for the treatment of groundwater contaminated with volatile organic compounds

Volatile organic compounds are a common source of groundwater contamination that can be easily removed by air stripping in columns with random packing and using a counter-current flow between the phases. This work proposes a new methodology for the column design for any particular type of packing and contaminant avoiding the necessity of a pre-defined diameter used in the classical approach. It also renders unnecessary the employment of the graphical Eckert generalized correlation for pressure drop estimates. The hydraulic features are previously chosen as a project criterion and only afterwards the mass transfer phenomena are incorporated, in opposition to conventional approach. The design procedure was translated into a convenient algorithm using C++ as programming language. A column was built in order to test the models used either in the design or in the simulation of the column performance. The experiments were fulfilled using a solution of chloroform in distilled water. Another model was built to simulate the operational performance of the column, both in steady state and in transient conditions. It consists in a system of two partial non linear differential equations (distributed parameters). Nevertheless, when flows are steady, the system became linear, although there is not an evident solution in analytical terms. In steady state the resulting system of ODE can be solved, allowing for the calculation of the concentration profile in both phases inside the column. In transient state the system of PDE was numerically solved by finite differences, after a previous linearization.

Experimental assessment of pressure drop in air stripping columns

One important step in the design of air stripping operations for the removal of VOC is the choice of operating conditions, which are based in the phase ratio. This parameter sets on directly the stripping factor and the efficiency of the operation. Its value has an upper limit determined by the flooding regime, which is previewed using empirical correlations, namely the one developed by Eckert. This type of approach is not suitable for the development of algorithms. Using a pilot scale column and a convenient solution, the pressure drop was determined in different operating conditions and the experimental values were compared with the estimations. This particular research will be incorporated in a global model for simulating the dynamics of air stripping using a multi variable distributed parameter system.

Practical software improve design and performance of a randomly packed air stripping column for removing volatile organic compounds from water

STRIPPING is a software application developed for the automatic design of a randomly packing column where the transfer of volatile organic compounds (VOCs) from water to air can be performed and to simulate it���s behaviour in a steady-state. This software completely purges any need of experimental work for the selection of diameter of the column, and allows a choice, a priori, of the most convenient hydraulic regime for this type of operation. It also allows the operator to choose the model used for the calculation of some parameters, namely between the Eckert/Robbins model and the Billet model for estimating the pressure drop of the gaseous phase, and between the Billet and Onda/Djebbar���s models for the mass transfer. Illustrations of the graphical interface offered are presented.

A New Approach in the Design of Air Stripping Columns for the Treatment of Groundwater Contaminated With Volatile Organic Compounds

Volatile organic compounds are a common source of groundwater contamination that can be easily removed by air stripping in columns with random packing and using a counter-current flow between the phases. This work proposes a new methodology for column design for any type of packing and contaminant which avoids the necessity of an arbitrary chosen diameter. It also avoids the employment of the usual graphical Eckert correlations for pressure drop. The hydraulic features are previously chosen as a project criterion. The design procedure was translated into a convenient algorithm in C++ language. A column was built in order to test the design, the theoretical steady-state and dynamic behaviour. The experiments were conducted using a solution of chloroform in distilled water. The results allowed for a correction in the theoretical global mass transfer coefficient previously estimated by the Onda correlations, which depend on several parameters that are not easy to control in experiments. For best describe the column behaviour in stationary and dynamic conditions, an original mathematical model was developed. It consists in a system of two partial non linear differential equations (distributed parameters). Nevertheless, when flows are steady, the system became linear, although there is not an evident solution in analytical terms. In steady state the resulting ODE can be solved by analytical methods, and in dynamic state the discretization of the PDE by finite differences allows for the overcoming of this difficulty. To estimate the contaminant concentrations in both phases in the column, a numerical algorithm was used. The high number of resulting algebraic equations and the impossibility of generating a recursive procedure did not allow the construction of a generalized programme. But an iterative procedure developed in an electronic worksheet allowed for the simulation. The solution is stable only for similar discretizations values. If different values for time/space discretization parameters are used, the solution easily becomes unstable. The system dynamic behaviour was simulated for the common liquid phase perturbations: step, impulse, rectangular pulse and sinusoidal. The final results do not configure strange or non-predictable behaviours.

Conceptual analogy for modelling entrapped air action in hydraulic systems

Hydraulic systems are dynamically susceptible in the presence of entrapped air pockets, leading to amplified transient reactions. In order to model the dynamic action of an entrapped air pocket in a confined system, a heuristic mathematical formulation based on a conceptual analogy to a mechanical spring-damper system is proposed. The formulation is based on the polytropic relationship of an ideal gas and includes an additional term, which encompasses the combined damping effects associated with the thermodynamic deviations from the theoretical transformation, as well as those arising from the transient vorticity developed in both fluid domains (air and water). These effects represent the key factors that account for flow energy dissipation and pressure damping. Model validation was completed via numerical simulation of experimental measurements.

Magnetic flux density distribution in the air gap of a ferromagnetic core with superconducting blocks: three-dimensional analysis and experimental NMR results

The design of magnetic cores can be carried out by taking into account the optimization of different parameters in accordance with the application requirements. Considering the specifications of the fast field cycling nuclear magnetic resonance (FFC-NMR) technique, the magnetic flux density distribution, at the sample insertion volume, is one of the core parameters that needs to be evaluated. Recently, it has been shown that the FFC-NMR magnets can be built on the basis of solenoid coils with ferromagnetic cores. Since this type of apparatus requires magnets with high magnetic flux density uniformity, a new type of magnet using a ferromagnetic core, copper coils, and superconducting blocks was designed with improved magnetic flux density distribution. In this paper, the designing aspects of the magnet are described and discussed with emphasis on the improvement of the magnetic flux density homogeneity (Delta B/B-0) in the air gap. The magnetic flux density distribution is analyzed based on 3-D simulations and NMR experimental results.

A r��dio na Internet: Do ���on air��� para o ���online���. Estudo de caso do servi��o p��blico e o caminho para o futuro

Trabalho de Projecto de Mestrado em Novos Media e Pr��ticas Web

Comparison of contaminant removal effectiveness and air change efficiency as indicator of air diffusion quality.

The ventilation efficiency concept is an attempt to quantify a parameter that can easily distinguish the different options for air diffusion in the building spaces. Thirteen strategies of air diffusion were measured in a test chamber through the application of the tracer gas method, with the objective to validate the calculation by Computational fluid dynamics (CFD). Were compared the Air Change Efficiency (ACE) and the Contaminant Removal Effectiveness (CRE), the two indicators most internationally accepted. The main results from this work shows that the values of the numerical simulations are in good agreement with experimental measurements and also, that the solutions to be adopted for maximizing the ventilation efficiency should be the schemes that operate with low speeds of supply air and small differences between supply air temperature and the room temperature.

Levels and risks of particulate-bound PAHs in indoor air influenced by tobacco smoke: a field measurement

Considering tobacco smoke as one of the most health-relevant indoor sources, the aim of this work was to further understand its negative impacts on human health. The specific objectives of this work were to evaluate the levels of particulate-bound PAHs in smoking and non-smoking homes and to assess the risks associated with inhalation exposure to these compounds. The developed work concerned the application of the toxicity equivalency factors approach (including the estimation of the lifetime lung cancer risks, WHO) and the methodology established by USEPA (considering three different age categories) to 18 PAHs detected in inhalable (PM10) and fine (PM2.5) particles at two homes. The total concentrations of 18 PAHs (��PAHs) was 17.1 and 16.6 ng m���3 in PM10 and PM2.5 at smoking home and 7.60 and 7.16 ng m���3 in PM10 and PM2.5 at non-smoking one. Compounds with five and six rings composed the majority of the particulate PAHs content (i.e., 73 and 78 % of ��PAHs at the smoking and non-smoking home, respectively). Target carcinogenic risks exceeded USEPA health-based guideline at smoking home for 2 different age categories. Estimated values of lifetime lung cancer risks largely exceeded (68���200 times) the health-based guideline levels at both homes thus demonstrating that long-term exposure to PAHs at the respective levels would eventually cause risk of developing cancer. The high determined values of cancer risks in the absence of smoking were probably caused by contribution of PAHs from outdoor sources.