Showing papers on "Air quality index published in 1999"

Case study of the effects of atmospheric aerosols and regional haze on agriculture: an opportunity to enhance crop yields in China through emission controls?

Abstract: The effect of atmospheric aerosols and regional haze from air pollution on the yields of rice and winter wheat grown in China is assessed. The assessment is based on estimates of aerosol optical depths over China, the effect of these optical depths on the solar irradiance reaching the earth’s surface, and the response of rice and winter wheat grown in Nanjing to the change in solar irradiance. Two sets of aerosol optical depths are presented: one based on a coupled, regional climate/air quality model simulation and the other inferred from solar radiation measurements made over a 12-year period at meteorological stations in China. The model-estimated optical depths are significantly smaller than those derived from observations, perhaps because of errors in one or both sets of optical depths or because the data from the meteorological stations has been affected by local pollution. Radiative transfer calculations using the smaller, model-estimated aerosol optical depths indicate that the so-called “direct effect” of regional haze results in an ≈5–30% reduction in the solar irradiance reaching some of China’s most productive agricultural regions. Crop-response model simulations suggest an ≈1:1 relationship between a percentage increase (decrease) in total surface solar irradiance and a percentage increase (decrease) in the yields of rice and wheat. Collectively, these calculations suggest that regional haze in China is currently depressing optimal yields of ≈70% of the crops grown in China by at least 5–30%. Reducing the severity of regional haze in China through air pollution control could potentially result in a significant increase in crop yields and help the nation meet its growing food demands in the coming decades.

Perceived air quality, sick building syndrome (SBS) symptoms and productivity in an office with two different pollution loads.

Abstract: Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in an existing office in which the air pollution level could be modified by introducing or removing a pollution source. This reversible intervention allowed the space to be classified as either non-low-polluting or low-polluting, as specified in the new European design criteria for the indoor environment CEN CR 1752 (1998). The pollution source was a 20-year-old used carpet which was introduced on a rack behind a screen so that it was invisible to the occupants. Five groups of six female subjects each were exposed to the conditions in the office twice, once with the pollution source present and once with the pollution source absent, each exposure being 265 min in the afternoon, one group at a time. They assessed the perceived air quality and SBS symptoms while performing simulated office work. The subject-rated acceptability of the perceived air quality in the office corresponded to 22% dissatisfied when the pollution source was present, and to 15% dissatisfied when the pollution source was absent. In the former condition there was a significantly increased prevalence of headaches (P = 0.04) and significantly lower levels of reported effort (p = 0.02) during the text typing and calculation tasks, both of which required a sustained level of concentration. In the text typing task, subjects worked significantly more slowly when the pollution source was present in the office (P = 0.003), typing 6.5% less text than when the pollution source was absent from the office Reducing the pollution load on indoor air proved to be an effective means of improving the comfort, health and productivity of building occupants.

Effect of rising Asian emissions on surface ozone in the United States

Abstract: The effect of increasing fossil fuel combustion in eastern Asia on surface O3 air pollution in the United States is examined with a global three-dimensional tropospheric chemistry model. Tripling of Asian anthropogenic emissions from 1985 to 2010 is expected to increase monthly mean O3 concentrations by 2–6 ppbv in the western United States and by 1–3 ppbv in the eastern United States, the maximum effect being in April–June. This increase would more than offset the benefits of 25% domestic reductions in anthropogenic emissions of NOx and hydrocarbons in the western United States. Asian influence may be less under the stagnant conditions leading to violations of the U.S. air quality standard. Nevertheless, our results suggest that a global perspective is necessary when designing a strategy to meet regional O3 air quality objectives.

The Power of Perception: Health Risk Attributed to Air Pollution in an Urban Industrial Neighbourhood

Abstract: This paper describes a multi-stakeholder process designed to assess the potential health risks associated with adverse air quality in an urban industrial neighborhood. The paper briefly describes the quantitative health risk assessment conducted by scientific experts, with input by a grassroots community group concerned about the impacts of adverse air quality on their health and quality of life. In this case, rather than accept the views of the scientific experts, the community used their powers of perception to advantage by successfully advocating for a professionally conducted community health survey. This survey was designed to document, systematically and rigorously, the health risk perceptions community members associated with exposure to adverse air quality in their neighborhood. This paper describes the institutional and community contexts within which the research is situated as well as the design, administration, analysis, and results of the community health survey administered to 402 households living in an urban industrial neighborhood in Hamilton, Ontario, Canada. These survey results served to legitimate the community’s concerns about air quality and to help broaden operational definitions of ‘health.’ In addition, the results of both health risk assessment exercises served to keep issues of air quality on the local political agenda. Implications of these findings for our understanding of the environmental justice process as well as the ability of communities to influence environmental health policy are discussed.

Analysis of Air Quality Data Using Positive Matrix Factorization

Abstract: Positive matrix factorization (PMF) was applied to air quality and temperature data collected as part of the Program for Research on Oxidants: Photochemistry, Emissions, and Transport 1997 summer measurement campaign. Unlike more conventional methods of factor analysis such as principal component analysis, PMF produces non-negative factors, aiding factor interpretation, and utilizes error estimates of the data matrix. This work uses PMF as a means of source identification and apportionment, important steps in the development of air pollution control strategies. Measurements of carbon monoxide, particulate matter, peroxyactyl nitrate (PAN), isoprene, temperature, and ozone were taken from a 31 m tower in rural northern Michigan and analyzed in this study. PMF resulted in three physically interpretable factors: an isoprene-dominated factor, a local source factor, and a long-range transport factor. The isoprene-dominated and local source factors exhibited strong and weak diurnal signals, respectively. Fact...

National estimates of outdoor air toxics concentrations.

Abstract: The Clean Air Act identifies 189 hazardous air pollutants (HAPs), or "air toxics," associated with a wide range of adverse human health effects. The U.S. Environmental Protection Agency has conducted a modeling study with the Assessment System for Population Exposure Nationwide (ASPEN) to gain a greater understanding of the spatial distribution of concentrations of these HAPs resulting from contributions of multiple emission sources. The study estimates year 1990 long-term outdoor concentrations of 148 air toxics for each census tract in the continental United States, utilizing a Gaussian air dispersion modeling approach. Ratios of median national modeled concentrations to estimated emissions indicate that emission totals without consideration of emission source type can be a misleading indicator of air quality. The results also indicate priorities for improvements in modeling methodology and emissions identification. Model performance evaluation suggests a tendency for underprediction of observed concentrations, which is likely due, at least in part, to a number of limitations of the Gaussian modeling formulation. Emissions estimates for HAPs have a high degree of uncertainty and contribute to discrepancies between modeled and monitored concentration estimates. The model's ranking of concentrations among monitoring sites is reasonably good for most of the gaseous HAPs evaluated, with ranking accuracy ranging from 66 to 100%.

Source Contributions to the Size and Composition Distribution of Atmospheric Particles: Southern California in September 1996

Abstract: An air quality model that follows the evolution of single particles in the atmosphere has been combined with new emissions measurements and then used to predict the size distribution and chemical composition of the airborne fine particle mixture observed at Long Beach, Fullerton, and Riverside, CA, during September 1996. Model predictions show good agreement with ambient measurements of particle size and chemical composition at all three air monitoring sites. The air quality model is used to separately track individual particles released from different sources as they evolve over time. Four major classes of particles are observed: (1) large mineral dust and road dust particles that accumulate only small amounts of secondary aerosol products; (2) primary combustion particles (released initially from diesel vehicles, noncatalyst gasoline-powered vehicles, and food processing) that grow by accumulation of secondary reaction products; (3) sea salt particles that are almost completely transformed by conversion from NaCl to NaNO_3 during transport across the air basin; and (4) sulfate-containing nonsea salt background particles advected into the air basin from upwind over the ocean. The sulfate-containing nonsea salt background particles have an initial PM2.5 concentration of only 8 μg m^(-3), but they accumulate significant secondary aerosol reaction products to produce a largely nitrate-containing aerosol having a PM2.5 concentration of 40 μg m^(-3) by the time that the air masses studied here reach Riverside, CA.

Urban Air Pollution - European Aspects

Abstract: Preface. I: Statement of the Problem. 1. About the Book J. Fenger, et al. 2. History of Urban Air Pollution P. Brimblecombe. 3. Europe and its Cities K.E. Gronskei. II: Urban Sources of Air Pollution. 4. Stationary Sources J.E. Johnsson. 5. Mobile Sources Z. Samaras, S.P. Sorensen. 6. Emission Inventories R. Friedrich, U.-B. Schwarz. III: Basic Atmospheric Phenomena. 7. Dynamical and Thermal Processes K.E. Gronskei. 8. Transformation of Air Pollutants R.G. Derwent, O. Hertel. 9. Particles H. Horvath. IV: Air Pollution Modelling. 10. Regional/Mesoscale Models G. Kallos. 11. Urban Scale Models P.G. Mestayer. 12. Street Scale Models R. Berkowicz. 13. Stochastic Models O. Herbarth, et al. 14. Wind Tunnel Experiments M. Schatzmann, et al. V: Air Quality Measurements. 15. Measurement Techniques I. Allegrini. 16. Monitoring Networks and Air Quality Management Systems S. Larssen. 17. Quality Assurance and Quality Control S. Larssne, C. Helmis. VI: Impacts of Urban Air Pollution. 18. Health Impacts O. Herbarth. 19. Materials Damage J. Tidblad, V. Kucera. 20. Impacts on Urban Vegetation and Ecosystems M. Ashmore. 21. Reduction of Visibility H. Horvath. VII: Policies, Legislation -- and a Final Overview. 22. Policies to Reduce Urban Air Pollution S. Krawack. 23. Air Quality Indicators P. Wiederkehr, S.-J. Yoon. 24. Limit Values L. Edwards. 25. Air Pollution in European Cities -- An Overview L. Bozo, et al. 26. Summary and Conclusions J. Fenger, et al. Index.

Formation of an Air Pollution Index.

Abstract: An air pollution index is a quantitative tool through which air pollution data can be reported uniformly. There have been efforts to describe overall air pollution by an aggregation of pollutant subindices. When ambiguous, these aggregations raise unnecessary alarm by declaring a less polluted air to be highly polluted. Similarly, when eclipsed, a false sense of security is provided by indicating highly polluted air as less polluted. Linear sum and root sum square forms in vogue suffer from ambiguity. Whereas the maximum operator aggregation does not consider change in the remaining pollutants, it is not a good tool for management purposes. In this paper, an ambiguity-and eclipsicity-free function has been presented for aggregation of air pollution subindices. For computer adaptation of the aggregation process, the subindices have been expressed as full range functions of the pollutant concentrations.

Observing air quality over the city of Nantes by means of Landsat thermal infrared data

Abstract: This article investigates the potentials of satellite-made observations for the mapping of air quality parameters. Ground measurements of black particulates, sulphur dioxide and other pollutants have been measured in the city of Nantes and are compared with coincident Landsat TM6 data. It is found that the amount in black particulates is highly correlated to the apparent temperature observed by satellite. Some of the possible mechanisms for this correlation are investigated. The influence of the pixel size on this correlation is discussed in view of previous studies. Preliminary explanations are given. The mapping of the spatial distribution of the black particulates is possible from remotely sensed data. It is not very accurate and possible improvements are discussed. Finally, it is shown that pollution level should be taken into account in any use of satellite data for urban area classification purposes.

Dynamically Consistent Formulations in Meteorological and Air Quality Models for Multiscale Atmospheric Studies. Part II: Mass Conservation Issues

Abstract: Eulerian air quality models that require gridded meteorological inputs have to adapt to recent advances in meteorological models for fully compressible atmosphere. When the input meteorological data are recast with a robust fully compressible governing set of equations, chemistry-transport models can follow the dynamic and thermodynamic descriptions of the meteorological data closely. For evaluating mass consistency in meteorological data, one may take advantage of the characteristics of the governing set of equations applicable for a specific vertical coordinate system. This paper discusses how the data from meteorological models should be used in air quality simulations. It proposes a general methodology to conserve mass of trace species in air quality models by maintaining consistency in the wind and air density fields. Limitations of several simplifying assumptions on atmospheric dynamics are also discussed. In summary, it attempts to bridge the information gap between dynamic meteorologists ...

Ventilation efficiencies of desk-mounted task/ambient conditioning systems

Abstract: In laboratory experiments, we investigated two task/ambient conditioning systems with air supplied from desk-mounted air outlets to efficiently ventilate the breathing zone of heated manikins seated at desks. In most experiments, the task conditioning systems provided outside air while a conventional ventilation system provided additional space cooling but no outside air. Air change effectiveness (i.e., exhaust air age divided by age of air at the manikin's face) was measured with a tracer gas step-up procedure. Other tracer gases simulated the release of pollutants from nearby occupants and from the floor covering, and the associated pollutant removal efficiencies (i.e., exhaust air concentrations divided by concentrations at manikin's face) were calculated. High values of air change effectiveness (approximately 1.3 to 1.9) and high values of pollutant removal efficiency (approximately 1.2 to 1.6) were measured when these task conditioning systems supplied 100% outdoor air at a flow rate of 7 to 9 L s-1 per occupant. Air change effectiveness was reasonably well correlated with the pollutant removal efficiency. Overall, the experimental data suggest that these task/ambient conditioning systems can be used to improve ventilation and air quality or to save energy while maintaining a typical level of IAQ at the breathing zone.

Indoor Air Quality Investigation on Commercial Aircraft

Abstract: Sixteen flights had been investigated for indoor air quality (IAQ) on Cathay Pacific aircraft from June 1996 to August 1997. In general, the air quality on Cathay Pacific aircraft was within relevant air quality standards because the average age of aircraft was less than 2 years. Carbon dioxide (CO2) levels on all flights measured were below the Federal Aviation Administration (FAA) standard (30,000 ppm). The CO2 level was substantially higher during boarding and de-boarding than cruise due to low fresh air supply. Humidity on the aircraft was low, especially for long-haul flights. Minimum humidity during cruise was below the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) minimum humidity standard (20%). The average temperature was within a comfortable temperature range of 23 +/- 2 degrees C. The vertical temperature profile on aircraft was uniform and below the International Standard Organization (ISO) standard. Carbon monoxide levels were below the FAA standard (50 ppm). Trace amount of ozone detected ranged from undetectable to 90 ppb, which was below the FAA standard. Particulate level was low for most non-smoking flights, but peaks were observed during boarding and de-boarding. The average particulate level in smoking flights (138 micrograms/m3) was higher than non-smoking flights (7.6 micrograms/m3). The impact on IAQ by switching from low-mode to high-mode ventilation showed a reduction in CO2 levels, temperature, and relative humidity.

Air pollution exposure monitoring and estimating. Part I. Integrated air quality monitoring system

Abstract: This paper presents an integrated exposure monitoring system, based on an expansion of existing air quality monitoring systems using dispersion modelling. The system allows: (1) identifying geographical areas whose inhabitants are most exposed to ambient pollution; (2) identifying how many people in an area are exposed to concentrations of pollution exceeding air quality guidelines; (3) describing the exposure of population subgroups (e.g. children); (4) planning pollution abatement measures and quantifying their effects; (5) establishing risk assessment and management programs, and (6) investigating the short- and long-term effects of both pollutants and pollution sources on public health. The effect of pollution is rarely very large and in order to discover it, exposure estimation must provide data that reflects both spatial and temporal variations. Estimates of pollution exposure are obtained using an integrated approach that combines results of measurements from monitoring programs with dispersion calculations. These values can serve as estimates for individual short-term or long-term exposure. The grouped data allows the expression of ambient pollution concentrations as the spatial distribution of estimates such as the mean or 98th percentile of such compounds as SO2, O3, NO2, PM10 and PM2.5. This integrated approach has been combined into a single software package, AirQUIS.