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M Helena Martins – One of the best experts on this subject based on the ideXlab platform.

  • Survey of volatile organic compounds associated with automotive emissions in the urban Airshed of São Paulo, Brazil
    Atmospheric Environment, 2001
    Co-Authors: Maribel Colón, Joachim D. Pleil, Thomas A Hartlage, M Lucia Guardani, M Helena Martins
    Abstract:

    Abstract The Metropolitan Region of Sao Paulo (MRSP), Brazil, is one of the largest metropolitan areas in the world (population 17 million, approx.) and relies heavily on alcohol-based fuels for automobiles. It is estimated that about 40% of the total volume of fuel is ethanol with some vehicles using pure ethanol and others a gasoline/ethanol blend. As such, Sao Paulo is an excellent example of an oxygenates-dominated Airshed of mobile sources and is most likely indicative of the future in heavily populated areas in the US such as Los Angeles where “oxy-fuels” are becoming an important replacement for the conventional pure petroleum-based fuels. In this work, we surveyed the ambient air to identify and quantify the organic compounds associated with the evaporative and exhaust emissions of these fuels and to begin to understand the potential for human exposure. Because this was an initial test without detailed prior knowledge of the Airshed of the area, we applied two different air sampling methods for various time periods to assess the ambient concentrations of a variety of polar and nonpolar volatile organic compounds (VOCs). For quality assurance (QA), we collected all the samples in duplicate (whole-air samples in Summa canisters and adsorbent-based samples on Perkin-Elmer Air Toxics tubes) at various flow rates to test performance. All samples were collected over identical time frames, typically for 1-, 2-, and 4-h periods per day at six different locations over a period of 1 week. Overall Sao Paulo results demonstrate that mean concentrations of single-ring aromatics are 2–3 times higher, volatile aldehydes are 5–10 times higher, and simple alcohols 10–100 times higher as compared to results of a recent study performed by EPA in the Los Angeles basin. C 4 –C 11 n –alkanes were only slightly elevated in Sao Paulo.

Javier Polanco – One of the best experts on this subject based on the ideXlab platform.

  • An Improved Method for Optical Characterization of Mineral Dust and Soot Particles in the El Paso-Juárez Airshed
    Atmosphere, 2020
    Co-Authors: Javier Polanco, Rosa M. Fitzgerald, Manuel Ramos, William R. Stockwell
    Abstract:

    Highly time-resolved aerosol measurements and analysis are necessary for a proper aerosol characterization in many polluted regions, because aerosol concentrations in polluted environments can change over time scales of minutes. However, many urban measuring sites have measuring devices that provide time resolved average aerosol concentrations over a day or two at best. Light-scattering properties of mineral dust and soot particles in the El Paso-Juarez Airshed were analyzed with an improved methodology, using the T-matrix, a maximum likelihood estimator (MLE), and data from both an acoustic extinctiometer and a laser particle counter. The hourly inter-comparisons of the scattering coefficients’ results between the model and those obtained using the instruments at a wavelength of 0.87 μm show good agreement. This methodology has been applied in the El Paso-Juarez Airshed successfully, and it could be used in other cities where mineral dust and soot are major components of the aerosol concentrations.

  • Use of light-extinction method and inverse modeling to study aerosols in the Paso del Norte Airshed
    Atmospheric Environment, 2011
    Co-Authors: Angel E. Esparza, Rosa Fitzgerald, Thomas E. Gill, Javier Polanco
    Abstract:

    A light-extinction technique for monitoring aerosols was used in conjunction with a robust inverse reconstruction model to retrieve aerosol size distribution. Results for the columnar aerosol size distribution for the Paso del Norte Airshed for two different pollution scenarios and at two different seasons were presented. These are well correlated with experimental surface aerosol data for this region. It was observed that, for the clean day scenario, the summer case showed a greater columnar concentration of smaller size aerosols than the winter case. Results for the columnar aerosol size distribution in the polluted day scenario demonstrated that the concentration of aerosols were greater in the summer than in the winter. In addition, HYSPLIT backward trajectories were used to identify pollution sources.

Cheryl E. Swanson – One of the best experts on this subject based on the ideXlab platform.

  • Diurnal variation of PM10 concentrations and its spatial distribution in the South East Queensland Airshed
    Clean air and environmental quality, 2007
    Co-Authors: Lidia Morawska, Devasenapathy Vishvakarman, Cheryl E. Swanson
    Abstract:

    The aim of this work was quantification of the diurnal variation of PM10 concentration and the variation in its spatial distribution in the South East Queensland (SEQ) Airshed with a specific focus on vehicle emissions as a contributing factor. The PM10 concentrations recorded at half-hourly intervals at six monitoring stations over a four-year period were used. Concentrations below 30 mug m-3 recorded at wind speeds less than 2.5 ms-1 and during times of clear visibility were selected for the analysis to lower the probability of interference from non-vehicular sources. The concentrations recorded between 2:00 and 5:00 am were considered to be the urban baseline and subtracted from the daytime readings to obtain a mean difference in concentration between daytime and night time. For a four-year period this mean difference in PM10 concentrations estimated for all the monitoring stations varied in the range between 3.8 and 6.9 mug m-3. In addition to the diurnal variation in the depth of the boundary layer (which was not quantified), vehicle emissions were concluded to be the major contributor to this variation. The method used in this study for quantification of the diurnal variation and spatial distribution of PM10 provides useful information on the influence of motor vehicle emissions on air quality, particularly in relation to human exposure. It provides information not directly available using source emission inventories, which yield data on the total emissions to the air, and cannot be directly translated into concentrations in the different areas of the Airshed.

  • Diurnal variation of PM10 concentrations and its spatial distribution in the South East Queensland Airshed
    , 2007
    Co-Authors: Lidia Morawska, Devasenapathy Vishvakarman, Cheryl E. Swanson
    Abstract:

    The aim of this work was quantification of the diurnal variation of PM10 concentrations and the variation in its spatial distribution in the South East Queensland (SEQ) Airshed with a specific focus on vehicle emissions as a contributing factor. The PM10 levels recorded at half-hourly intervals at six monitoring stations over a four-year period were used. Levels below 30 g m-3 recorded at wind speeds less than 2.5 ms-1 and during times of clear visibility were selected for the analysis to lower the probability of interference from non-vehicular sources. The levels recorded between 2:00 and 5:00 am were considered to be the urban baseline and subtracted from the daytime readings to obtain a mean difference in concentration between daytime and night time. For a four-year period this mean difference in PM10 levels estimated for all the monitoring stations varied in the range between 3.8 and 6.9 g m-3. In addition to the diurnal variation in the depth of the boundary layer (which was not quantified), vehicle emissions were concluded to be the major contributor to this variation. The method used in this study for quantification of the diurnal variation and spatial distribution of PM10 provides useful information on the influence of motor vehicle emissions on air quality, particularly in relation to human exposure. It provides information not directly available using source emission inventories, which yield data on the total emissions to the air, and cannot be directly translated into concentrations in the different areas of the Airshed.

Mackenzie Rob – One of the best experts on this subject based on the ideXlab platform.

Manju Mohan – One of the best experts on this subject based on the ideXlab platform.

  • assessment of contribution to pm10 concentrations from long range transport of pollutants using wrf chem over a subtropical urban Airshed
    Atmospheric Pollution Research, 2013
    Co-Authors: Medhavi Gupta, Manju Mohan
    Abstract:

    Abstract A regional chemical trantransport model was implemented to simulate the Respirable Suspended Particulate Matter (PM 10 ) concentration in order to study the impact of long–range transport of air pollutants over megacity Delhi with due consideration to different geographical domains extending up to entire Asia and corresponding emissions. PM 10 concentration levels over megacity Delhi remain persistently high, often exceeding the ambient air quality standards. A chemical trantransport model namely Weather Research and Forecasting (WRF) model Version 3.2 coupled with chemistry module (WRF/Chem) was utilized with nested domains for this purpose, subsequent to model evaluation for the period during June, 2010 that includes extremely high PM 10 concentrations. A highly satisfactory model performance was interpreted based on the several statistical parameters as per the current state of the science and their recommended values. Based on model simulations representing different geographical domains encompassing Asia, India, North India and Delhi and their corresponding emissions, it was clearly reflected that contributions due to emissions of the megacity Delhi alone is 11%–41% and thus remaining (59%–89%) proportion is expected to be contributed from the sources outside of the Delhi region which is significant. It is demonstrated that the WRF/Chem model performs well for a sub–tropical urban Airshed though there is scope of improvement for the consistent under– prediction with more refined emission inventories. Nevertheless, this model could be implemented to assess the long– range transport of pollutants so as to adequately address the influence of the remote sources outside the urban Airshed. This can serve as an important tool towards planning and implementing the regulatory policies for air pollution control for more effective outcomes.

  • Assessment of contribution to PM10 concentrations from long range transport of pollutants using WRF/Chem over a subtropical urban Airshed
    Atmospheric Pollution Research, 2013
    Co-Authors: Medhavi Gupta, Manju Mohan
    Abstract:

    Abstract A regional chemical trantransport model was implemented to simulate the Respirable Suspended Particulate Matter (PM 10 ) concentration in order to study the impact of long–range transport of air pollutants over megacity Delhi with due consideration to different geographical domains extending up to entire Asia and corresponding emissions. PM 10 concentration levels over megacity Delhi remain persistently high, often exceeding the ambient air quality standards. A chemical trantransport model namely Weather Research and Forecasting (WRF) model Version 3.2 coupled with chemistry module (WRF/Chem) was utilized with nested domains for this purpose, subsequent to model evaluation for the period during June, 2010 that includes extremely high PM 10 concentrations. A highly satisfactory model performance was interpreted based on the several statistical parameters as per the current state of the science and their recommended values. Based on model simulations representing different geographical domains encompassing Asia, India, North India and Delhi and their corresponding emissions, it was clearly reflected that contributions due to emissions of the megacity Delhi alone is 11%–41% and thus remaining (59%–89%) proportion is expected to be contributed from the sources outside of the Delhi region which is significant. It is demonstrated that the WRF/Chem model performs well for a sub–tropical urban Airshed though there is scope of improvement for the consistent under– prediction with more refined emission inventories. Nevertheless, this model could be implemented to assess the long– range transport of pollutants so as to adequately address the influence of the remote sources outside the urban Airshed. This can serve as an important tool towards planning and implementing the regulatory policies for air pollution control for more effective outcomes.