A31D-01 08:00h
LIDAR Observations of the Vertical Ozone and Aerosol Distribution over Mexico City during the MCMA-2003 Field Campaign
An international field measurement campaign was held in April - May 2003 in the Mexico City Metropolitan Area (MCMA) as part of an effort to understand the complex urban air pollution problems in large cities. Gas phase and aerosol constituents were studied intensively during the campaign. LIDAR played an important role for measuring boundary layer dynamics and photochemical processes by monitoring the vertical distribution of aerosols and ozone. Two elastic DIAL and one Raman DIAL for ozone measurements were operated quasi-simultaneously during the campaign at the CENICA super site. The lidar of the Swiss Federal Institute of Technology, Lausanne (EPFL), Switzerland is an elastic three-wavelength UV DIAL combined with an aerosol lidar at 532 nm with an operational range of 200-6000 m for ozone measurements and 200-10000 m for aerosol measurements. The other elastic system is a commercial, stand alone two-wavelength DIAL produced and operated by ELIGHT Laser Systems GmbH. It performed ozone measurements from 400 to 2000 m. A combined Raman DIAL and aerosol Raman system was on loan from Freie Universität Berlin. This instrument was operated by the MIT team and provided ozone concentration from 350 to 2600 m and multicolor aerosol backscatter, Raman and depolarization. The campaign was designed to cover the height of the annual photochemical season. Rain episodes during the afternoons and the evenings at the beginning of the campaign caused discontinuity in the observation. Improved meteorological conditions from April 25 to May 3 made continuous measurements of all participating Lidars possible. A cloud-topped boundary layer (BL) was the frequently observed in the afternoon during this period. The top of the BL estimated from the aerosol measurements showed steady day-to-day increase, reaching altitudes of up to 4 km, comparable to the altitudes of the surrounding mountains. An obvious detachment of the top of the BL was also observed by the EPFL Lidar during the last two days of the campaign. The intercomparison of the ozone profiles measured with the three Lidar systems shows good agreement in the overlap regions. Steady increase in the daily values of ozone concentrations and the formation of a residual layer were clearly seen in the ozone time series. The detachment of the BL observed in the aerosol data was also present in the ozone time series. Elevated ozone concentrations measured at high altitudes were found together with relatively clean air masses in the altitude region 500-700 m AGL. Wind speed and wind direction measured simultaneously with a tethered balloon showed significant wind shear in this altitude range giving a possible reason for the lower ozone and aerosol concentrations in the 500-700 m region.
A31D-02 08:15h
Mobile Laboratory Measurements of On-Road Vehicle Air Toxics Emissions in Mexico City
The direct emission of toxic organic pollutants from mobile sources is an issue of growing concern. The U.S. Environmental Protection Agency (EPA) and the Federal Highway Administration (FHWA) have identified formaldehyde, acetaldehyde, benzene, acrolein, 1.3 butadiene, and diesel particulate matter (PM), including associated organic compounds, as mobile emissions of priority concern. Real-time trace gas and fine PM sensors deployed on the Aerodyne Research Mobile Laboratory have been used to characterize both fleet average and individual vehicle class on-road emissions of formaldehyde, acetaldehyde, benzene, and diesel particulate matter (PM), including associated organic compounds in the Mexico City Metropolitan Area (MCMA). Data for these air toxics emissions will be reviewed and compared to similar data taken in Boston and New York City, where available. The prospects for future on-road real-time monitoring of acroleinand1.3 butadiene will be discussed.
A31D-03 08:30h
Impacts of Air Pollution on Health in Eastern China: Implications for future air pollution and energy policies
Our objective is to establish the link between energy consumption and technologies, air pollution and resulting impacts on public health in eastern China. We quantify the impacts that air pollution in the Shandong region of eastern China has on public health in 2000 and quantify the benefits in improved air quality and health that could be obtained by 2020, relative to business-as-usual, through the implementation of new energy technology. We first develop a highly-resolved emission inventory for the year 2000 for the Shandong region of China including emissions from large point, area, mobile and biogenic sources. We use the Sparse Matrix Operator Kernel Emissions Modeling System (SMOKE) to process emissions from this inventory for use in the Community Multi-scale Air Quality modeling system (CMAQ) which we drive with the NCAR/PSU MM5 meso-scale meteorology model. We evaluate the inventory by comparing CMAQ results with available measurements of PM10 and SO2 from air pollution indices (APIs) reported in various Chinese municipalities during 2002-2004. We use epidemiological dose-response functions to quantify health impacts and values of a statistical life (VSL) and years-of-life-lost (YLL) to establish a range for the monetary value of these impacts. To examine health impacts and their monetary value, we focus explicitly on Zaozhuang, a coal-intensive city in the Shandong region of eastern China, and quantify the mortalities and morbidities resulting from air pollutants emitted from this city in 2000, and in 2020 using business-as-usual, best-available control technology, and advanced coal gasification technology scenarios. In all scenarios most health damages arise from exposure to particulate matter. We find that total health damages due to year 2000 anthropogenic emissions from Zaozhuang accounted for 4-10% of its GDP. If all health damages resulting from coal use were internalized in the market price of coal, the year 2000 price would have doubled. With no new air pollution controls implemented between 2000 and 2020, we predict health damages from air pollution exposure will quadruple and account for 8-16% of Zaozhuang's 2020 GDP. End-of-pipe controls could reduce the potential health damages from air pollution by 20% and a coal gasification polygeneration energy system could reduce it by 50% with only 24% penetration. Benefits to public health, of substantial monetary value, could be achieved in eastern China through the use of currently available end-of-pipe controls; with further development, benefits from the use of advanced coal technology could be even larger.
A31D-04 08:45h
Quantifying the Benefits of Transportation Controls in the Mexico City Metropolitan Area
Similar to most large cities, the transportation sector in the Mexico City Metropolitan Area (MCMA) constitutes the largest source of air pollution emissions, which result in significant impacts on human health. Although the majority of MCMA residents use public transportation, the share of trips in private vehicles is rising and these vehicles have become the largest contributor to mobile emissions. To reduce these emissions, there is an urgent need to improve the current fleet, improve the quality of fuels, and modify the paradigm of private car use, by providing clean, safe, efficient and comfortable public transportation options. Here we present the potential human health benefits of a set of five mobile source control measures that span public and private transportation options: Taxi fleet renovation, Hybrid buses, Metro Expansion, and the introduction of low sulfur gasoline and Tier II vehicles. We also discuss the methodology and preliminary results of the analysis of the implementation of the project for a Bus Rapid Transit system in Mexico City, in terms of its impacts on personal exposures, emissions, and public health.
A31D-05 09:00h
The Double Counting Problem in Neighborhood Scale Air Quality Modeling
Air quality varies considerably within megacities. In certain neighborhoods concentrations of toxic air contaminants (TACs) can be appreciably higher than that in other neighborhoods of the same city. These pockets of high concentrations are associated with both transport of TACs from other areas and local emissions. In order to assess the health risks imposed by TACs at neighborhood scale and to develop strategies of abatement, neighborhood scale air quality modeling is needed. In 1999, the California Air Resources Board (ARB) established the Neighborhood Assessment Program (NAP) - a program designed to develop assessment tools for evaluating and understanding air quality in California communities. As part of the Neighborhood Assessment Program, ARB is conducting research on neighborhood-scale modeling methodologies. Two criteria are suggested to select a neighborhood scale air quality modeling system that can be used to assess concentrations of TACs: scientific soundness and balancing computational requirements. The latter criterion ensures that as many interested parties as possible can participate the process of air quality modeling so that they have a better understanding of air quality issues and make best use of air quality modeling results in their neighborhoods. Based on these two selection criteria a hybrid approach is recommended. This hybrid approach is a combination of using both a regional scale air quality model to assess the contributions from sources that are not located within the neighborhood of interest and a microscale model to assess the impact from the local sources that are within the neighborhood. However, one of the modeling system selection criteria, balancing computational requirements, dictates that all sources (both within and outside the neighborhood of interest) must be included in the regional scale modeling. A potential problem, referred to as double counting, arises because some local sources are included in both regional and microscale modeling. To address this issue, a box model is developed to calculate the impact of double counted sources so that their effect on the total concentration (i.e., concentration due to all sources) can be minimized or even eliminated.
A31D-06 09:12h
Air Quality in the Central Ontario Region
The Central Ontario Region (COR) is the most densely populated area in Canada. With a population of 7.3 million, it contains 23% of the total population of Canada. It extends from the extreme south west end of Ontario to the eastern end of the Greater Toronto Area (GTA) and includes the Niagara, Hamilton and Waterloo Regions,. The air quality of this region is frequently severely impaired in the summer months. In the larger metropolitan areas (Toronto and Hamilton) air pollution is a concern throughout the year. Local health authorities attribute about 1000 premature deaths per year in the GTA alone to air pollution. Average air pollution levels in Ontario have decreased significantly during the past 30 years, despite significant growth in both population and industry. The concentrations of SO2 and CO have decreased by over 80% and the concentration of NOX has decreased by about 50% over the past 26 years. Currently, the concentrations of NOX, CO, SO2 and VOCs in the COR are well below the Provincial and Federal air quality criteria. Ozone, PM2.5 and PM10, however, remain above the Provincial guidelines, so smog still remains a problem. The pollutants in the atmosphere of the COR are caused by both local emissions and long range transport. The COR contributes over 50% of the NOx, VOC and CO emissions in Ontario. Over 58% of NOX and CO emissions in the COR are due to mobile sources while about 50% of VOC and PM emissions are due to area sources. The proximity of the COR to the Canada-U.S. border makes it vulnerable to long range transport of pollutants stemming from the much larger population in the United States. The Canadian government, industries and non-governmental organizations are all taking steps to help reduce the level of pollution in Canada. The Canadian federal government also participates in extensive consultations and cooperative programs with the United States designed to reduce the mutually detrimental effects of cross-border pollution. These initiatives are important because substantial improvements in the COR air quality must be made to avoid significant deterioration in the respiratory health of the population.
A31D-07 09:24h
Effect of Population Growth and Pollution on the Air Quality over Mega Cities of Ganga Basin
The Indo Gangetic (IG) basin is one of the largest basins on the Earth where approximately one third (360 million) of the Indian population live. This basin is a highly agriculturally productive and industrial basin, due to this and other anthropogenic activities the pollution level is increasing. The increasing aerosol pollution over the IG basin is especially prominent and has been mapped first time by the ADEOS-Polder data and now the effect of pollution is seen from recent satellites onboard. Evidence suggests that the widespread and persistent nature of the pollution is even modifying the regional weather and climate patterns. In the present paper, we show the trend of air quality parameters measured on the ground and also from the satellites over various cities lying in the Ganga basin. We show the effect on population and increasing vehicles on the air quality of the major cities. Further, we show the influence of pollution on the total ozone concentration. The effect of increasing pollution is clearly seen from the air quality trend and the total ozone content over the major cities over the Ganga basin, on the contrast such effect is not seen over the Indian cities lying in the southern and central parts of India.
A31D-08 09:36h
Heavy-Duty Vehicle Emissions in the Mexico City Metropolitan Area during the MCMA-2003 Field Measurement Campaign
On-road vehicle emissions were measured in the Mexico City Metropolitan Area (MCMA) as part of an intensive, five-week, field campaign held in the spring of 2003 (April 1 - May 5). Vehicle emissions measurements were made during vehicle chase experiments using the Aerodyne Mobile Laboratory. The mobile lab was equipped with a large suite of state-of-the-art analytical instruments for measuring both gas and particle phase chemical components from vehicle emissions in real time. The experiment represents a real-world sample of more than 200 in-use vehicles. The results presented here focus on heavy-duty gasoline (HDGT) and heavy-duty diesel trucks (HDDT), although measurements included pick up trucks, colectivos (microbuses), and private automobiles as well. The use of covariance and fitting methods for individual species vs. CO2 allows the estimation of individual emission ratios in a real time plume-based analysis. The variability of emission ratios within a vehicle class and during different driving modes (acceleration, idling, etc.) are explored. Results are reported as molar emission ratios of emission gases with carbon dioxide. These and other vehicle-related emissions measured during the campaign will be presented and discussed. These types of studies are important for the development of emission inventories and their use in air quality modeling studies in urban areas.
A31D-09 09:48h
Spatial distribution of gases emitted from large urban areas derived from SF6 measurements
A 6 year (1998-2003) long, high-resolution, time series of atmospheric SF6 from Lamont Doherty Earth Observatory (LDEO), ~ 25 km north of New York City (NYC), has shown that SF6 mixing ratios are highly variable and elevated above remote atmosphere values. Subsequent measurements in soil air (which functions as a low-pass filter) around the New York metropolitan area demonstrate that elevated SF6 levels are widespread. Mapping of the elevated SF6 levels caused by local emissions in NYC allows us to determine the region influenced by emissions from this urban area. To determine if such elevated SF6 levels are typical for large US cities, soil air measurements were repeated in five major urban areas in the US. In each case, significant elevation of SF6 mixing ratios above remote atmosphere values was observed. SF6 emissions from the electrical industry in NYC are particular high, resulting in average mixing ratios within the city in excess of remote atmosphere values by up to 200 %, with elevated levels persisting out to ca. 200 km. Emissions from Boston, Philadelphia, Washington DC/Baltimore, and Tucson appear average for large cities in the U.S.A. with maximum mixing ratios 50-100% above background, and elevated levels detected over tens of kilometers. Using a simplistic atmospheric dispersion model and emissions records, the observed distribution of average SF6 mixing ratios around NYC can be reproduced. This indicates that studies using similar methods, with higher spatial resolution, coupled with modeling of atmospheric transport may allow independent estimates of emissions of SF6, or other inert gases. Observed distributions of SF6 are indicative of average atmospheric transport patterns, and elevated levels of SF6 in remote areas demonstrate significant influence of air masses from urban areas. Comparison of SF6 timeseries at LDEO and Harvard Forest, 205 km to the northeast, demonstrate transport of individual pollution events.