Showing papers on "Air quality index published in 2009"
TL;DR: This article found that climate change alone will increase summertime surface ozone in polluted regions by 1-10 ppb over the coming decades, with the largest effects in urban areas and during pollution episodes.
1,470 citations
University of Leicester1, Earth System Research Laboratory2, Centre national de la recherche scientifique3, Cooperative Institute for Research in Environmental Sciences4, Norwegian Institute for Air Research5, United Kingdom Department for Environment, Food and Rural Affairs6, Japan Agency for Marine-Earth Science and Technology7, International Institute for Applied Systems Analysis8, Danish Meteorological Institute9, Paul Scherrer Institute10, ETH Zurich11, University of California, Irvine12, University of Leeds13, Aristotle University of Thessaloniki14, École Polytechnique Fédérale de Lausanne15, Geophysical Fluid Dynamics Laboratory16, National Center for Atmospheric Research17, Stockholm University18, Swiss Federal Laboratories for Materials Science and Technology19, Forschungszentrum Jülich20, University of Oslo21, Max Planck Society22, University of Helsinki23, Blaise Pascal University24, Joseph Fourier University25, University of York26, University of Toulouse27, University of Urbino28, University of Manchester29, National University of Ireland, Galway30, University of Edinburgh31, Heidelberg University32, University of East Anglia33, Weizmann Institute of Science34, Chalmers University of Technology35, Norwegian Meteorological Institute36, Energy Research Centre of the Netherlands37, University of Stuttgart38, VU University Amsterdam39
TL;DR: A review of the state of scientific understanding in relation to global and regional air quality is outlined in this article, in terms of emissions, processing and transport of trace gases and aerosols.
760 citations
TL;DR: In this article, it was shown that air pollution is transported across continents and ocean basins due to fast long-range transport, resulting in trans-oceanic and trans-continental plumes of atmospheric brown clouds (ABCs) containing sub micron size particles, which lead to a large surface dimming.
728 citations
TL;DR: In this paper, the authors evaluate the global impact of surface ozone on four types of agricultural crop using modelled global hourly ozone fields for the year 2000 and 2030, using the global 1 � � 1�
621 citations
TL;DR: In this article, the authors use the life satisfaction approach to value air quality, combining individual-level panel and high-resolution SO2 data, and construct a novel instrument exploiting the natural experiment created by the mandated scrubber installation at power plants, with wind directions dividing counties into treatment and control groups.
Abstract: I use the life satisfaction approach to value air quality, combining individual-level panel and high-resolution SO2 data. To avoid simultaneity problems, I construct a novel instrument exploiting the natural experiment created by the mandated scrubber installation at power plants, with wind directions dividing counties into treatment and control groups. I find a negative effect of pollution on well-being that is larger for instrumental variable than conventional estimates, robust to controls for local unemployment, particulate pollution, reunification effects and rural/urban trends, and larger for environmentalists and predicted risk groups. To calculate total willingness-to-pay, the estimates are supplemented by hedonic housing regressions.
474 citations
TL;DR: It is suggested that ground-based measurements, models, and satellite measurements should be viewed as a system, each component of which is necessary to better understand air quality.
Abstract: The recent literature on satellite remote sensing of air quality is reviewed. 2009 is the 50th anniversary of the first satellite atmospheric observations. For the first 40 of those years, atmospheric composition measurements, meteorology, and atmospheric structure and dynamics dominated the missions launched. Since 1995, 42 instruments relevant to air quality measurements have been put into orbit. Trace gases such as ozone, nitric oxide, nitrogen dioxide, water, oxygen/tetraoxygen, bromine oxide, sulfur dioxide, formaldehyde, glyoxal, chlorine dioxide, chlorine monoxide, and nitrate radical have been measured in the stratosphere and troposphere in column measurements. Aerosol optical depth (AOD) is a focus of this review and a significant body of literature exists that shows that ground-level fine particulate matter (PM2.5) can be estimated from columnar AOD. Precision of the measurement of AOD is +/-20% and the prediction of PM2.5 from AOD is order +/-30% in the most careful studies. The air quality needs that can use such predictions are examined. Satellite measurements are important to event detection, transport and model prediction, and emission estimation. It is suggested that ground-based measurements, models, and satellite measurements should be viewed as a system, each component of which is necessary to better understand air quality.
458 citations
TL;DR: In this article, a different approach was presented to evaluate how the spatial heterogeneity of the urban forest influences air pollution removal at the socioeconomic subregion scale, which can be used to design management alternatives at finer administrative scales such as districts and neighborhoods that maximize the pollution removal rates by the urban forests in a subregion.
419 citations
04 Nov 2009
TL;DR: The Common Sense project is developing participatory sensing systems that allow individuals to measure their personal exposure, groups to aggregate their members' exposure, and activists to mobilize grassroots community action.
Abstract: Poor air quality is a global health issue, causing serious problems like asthma, cancer, and heart disease around the world. Earlier this decade, the World Health Organization estimated that three million people die each year from the effects of air pollution [6]. Unfortunately, while variations in air quality are significant, today's air quality monitors are very sparsely deployed. To address this visibility gap, the Common Sense project is developing participatory sensing systems that allow individuals to measure their personal exposure, groups to aggregate their members' exposure, and activists to mobilize grassroots community action.
403 citations
TL;DR: In this paper, the authors report the first continuous record of surface ozone in the background atmosphere of South China, which was obtained from 1994 to 2007 at a coastal site in Hong Kong, which is strongly influenced by the outflow of Asian continental air during the winter and the inflow of maritime air from the subtropics in the summer.
Abstract: . Tropospheric ozone is of great importance with regard to air quality, atmospheric chemistry, and climate change. In this paper we report the first continuous record of surface ozone in the background atmosphere of South China. The data were obtained from 1994 to 2007 at a coastal site in Hong Kong, which is strongly influenced by the outflow of Asian continental air during the winter and the inflow of maritime air from the subtropics in the summer. Three methods are used to derive the rate of change in ozone. A linear fit to the 14-year record shows that the ozone concentration increased by 0.58 ppbv/yr, whereas comparing means in years 1994–2000 and 2001–2007 gives an increase of 0.87 ppbv/yr for a 7-year period. The ozone changes in air masses from various source regions are also examined. Using local wind and carbon monoxide (CO) data to filter out local influence, we find that ozone increased by 0.94 ppbv/yr from 1994–2000 to 2001–2007 in air masses from Eastern China, with similar changes in the other two continent-influenced air-mass groups, but no statistically significant change in the marine air. An examination of the nitrogen dioxide (NO2) column obtained from GOME and SCIAMACHY reveals an increase in atmospheric NO2 in China's three fastest developing coastal regions, whereas NO2 in other parts of Asia decreased during the same period, and no obvious trend over the main shipping routes in the South China Sea was indicated. Thus the observed increase in background ozone in Hong Kong is most likely due to the increased emissions of NO2 (and possibly volatile organic compounds (VOCs) as well) in the upwind coastal regions of mainland China. The CO data at Hok Tsui showed less definitive changes compared to the satellite NO2 column. The increase in background ozone likely made a strong contribution (81%) to the rate of increase in "total ozone" at an urban site in Hong Kong, suggesting the need to consider distant sources when developing long-term strategies to mitigate local ozone pollution.
369 citations
TL;DR: This paper developed an alternative discrete-choice approach that models the household location decision directly, and applied it to the case of air quality in US metro areas in 1990 and 2000, showing that when moving is costly, the variation in housing prices and wages across locations may no longer reflect the value of differences in local amenities.
364 citations
TL;DR: This paper examined the impact of three "criteria" air pollutants on infant health in New Jersey in the 1990s by combining information about mother's residential location from birth certificates with information from air quality monitors, finding consistently negative effects of exposure to carbon monoxide (CO) both during and after birth, with effects considerably larger for smokers and older mothers.
TL;DR: In this paper, the authors give an overview of vegetation fire emissions, their environmental and climate impact, and what improvements can be expected in the near future. But they do not consider the impact of fire-related emissions on air pollution and climate.
TL;DR: The authors empirically test existing theories on the provision of public goods, in particular air quality, using data on sulfur dioxide (SO2) concentrations from the Global Environment Monitoring Projects for 107 cities in 42 countries from 1971 to 1996.
TL;DR: In this paper, the emissions from the combustion of fossil fuels and bio-fuels and their atmospheric impacts are reviewed with attention given to the emissions of currently regulated pollutant gasses, primary aerosols, and secondary aerosol precursors as well as emissions of non-regulated pollutants.
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TL;DR: In this paper, the average marginal rate of substitution between income and air quality was derived for a time-varying local public good: air quality, and the results showed that people interviewed on days when air pollution was worse than the local seasonal average reported lower levels of happiness.
Abstract: This paper describes and implements a method for estimating the average marginal value of a time-varying local public good: air quality. It uses the General Social Survey (GSS), which asks thousands of people in various U.S. locations how happy they are, along with other demographic and attitude questions. These data are matched with the Environmental Protection Agency's Air Quality System (AQS) to find the level of pollution in those locations on the dates the survey questions were asked. People with higher incomes in any given year and location report higher levels of happiness, and people interviewed on days when air pollution was worse than the local seasonal average report lower levels of happiness. Combining these two concepts, I derive the average marginal rate of substitution between income and air quality - a compensating variation for air pollution.
TL;DR: In this article, the authors examined optimal control strategies of variable air volume air conditioning system, which included a base control strategy of fixed temperature set point and two advanced strategies for insuring comfort and indoor air quality (IAQ).
TL;DR: In this paper, the influence of specific sources of inorganic PM2.5 on peak and ambient aerosol concentrations in the US are evaluated using a combination of inverse modeling and sensitivity analysis.
Abstract: . Influences of specific sources of inorganic PM2.5 on peak and ambient aerosol concentrations in the US are evaluated using a combination of inverse modeling and sensitivity analysis. First, sulfate and nitrate aerosol measurements from the IMPROVE network are assimilated using the four-dimensional variational (4D-Var) method into the GEOS-Chem chemical transport model in order to constrain emissions estimates in four separate month-long inversions (one per season). Of the precursor emissions, these observations primarily constrain ammonia (NH3). While the net result is a decrease in estimated US~NH3 emissions relative to the original inventory, there is considerable variability in adjustments made to NH3 emissions in different locations, seasons and source sectors, such as focused decreases in the midwest during July, broad decreases throughout the US~in January, increases in eastern coastal areas in April, and an effective redistribution of emissions from natural to anthropogenic sources. Implementing these constrained emissions, the adjoint model is applied to quantify the influences of emissions on representative PM2.5 air quality metrics within the US. The resulting sensitivity maps display a wide range of spatial, sectoral and seasonal variability in the susceptibility of the air quality metrics to absolute emissions changes and the effectiveness of incremental emissions controls of specific source sectors. NH3 emissions near sources of sulfur oxides (SOx) are estimated to most influence peak inorganic PM2.5 levels in the East; thus, the most effective controls of NH3 emissions are often disjoint from locations of peak NH3 emissions. Controls of emissions from industrial sectors of SOx and NOx are estimated to be more effective than surface emissions, and changes to NH3 emissions in regions dominated by natural sources are disproportionately more effective than regions dominated by anthropogenic sources. NOx controls are most effective in northern states in October; in January, SOx controls may be counterproductive. When considering ambient inorganic PM2.5 concentrations, intercontinental influences are small, though transboundary influences within North America are significant, with SOx emissions from surface sources in Mexico contributing almost a fourth of the total influence from this sector.
TL;DR: Exposure to TRAP was significantly associated with increased all-cause and circulatory mortality in this cohort, and a high prevalence of cardiopulmonary disease in the cohort probably limits inference of the findings to populations with a substantial proportion of susceptible individuals.
Abstract: BackgroundChronic exposure to traffic-related air pollution (TRAP) may contribute to premature mortality, but few studies to date have addressed this topic.ObjectivesIn this study we assessed the a...
TL;DR: Given the serious concerns raised regarding the amount and the impacts of agricultural air emissions, policies must be pursued and regulations must be enacted in order to make real progress in reducing these emissions and their associated environmental impacts.
Abstract: Scientific assessments of agricultural air quality, including estimates of emissions and potential sequestration of greenhouse gases, are an important emerging area of environmental science that offers significant challenges to policy and regulatory authorities. Improvements are needed in measurements, modeling, emission controls, and farm operation management. Controlling emissions of gases and particulate matter from agriculture is notoriously difficult as this sector affects the most basic need of humans, i.e., food. Current policies combine an inadequate science covering a very disparate range of activities in a complex industry with social and political overlays. Moreover, agricultural emissions derive from both area and point sources. In the United States, agricultural emissions play an important role in several atmospherically mediated processes of environmental and public health concerns. These atmospheric processes affect local and regional environmental quality, including odor, particulate matter (PM) exposure, eutrophication, acidification, exposure to toxics, climate, and pathogens. Agricultural emissions also contribute to the global problems caused by greenhouse gas emissions. Agricultural emissions are variable in space and time and in how they interact within the various processes and media affected. Most important in the U.S. are ammonia (where agriculture accounts for approximately 90% of total emissions), reduced sulfur (unquantified), PM25 (approximately 16%), PM110 (approximately 18%), methane (approximately 29%), nitrous oxide (approximately 72%), and odor and emissions of pathogens (both unquantified). Agriculture also consumes fossil fuels for fertilizer production and farm operations, thus emitting carbon dioxide (CO2), oxides of nitrogen (NO(x)), sulfur oxides (SO(x)), and particulates. Current research priorities include the quantification of point and nonpoint sources, the biosphere-atmosphere exchange of ammonia, reduced sulfur compounds, volatile organic compounds, greenhouse gases, odor and pathogens, the quantification of landscape processes, and the primary and secondary emissions of PM. Given the serious concerns raised regarding the amount and the impacts of agricultural air emissions, policies must be pursued and regulations must be enacted in orderto make real progress in reducing these emissions and their associated environmental impacts.
TL;DR: The Intercontinental Chemical Transport Experiment-B (INTEX-B) was a major NASA led multi-partner atmospheric field campaign completed in the spring of 2006 ( http://cloud1.arc.nasa.gov/intex-b/ ). Its major objectives aimed at investigating the extent and persistence of the outflow of pollution from Mexico; understanding transport and evolution of Asian pollution and implications for air quality and climate across western North America; and validating space-borne observations of tropospheric composition as discussed by the authors.
Abstract: . Intercontinental Chemical Transport Experiment-B (INTEX-B) was a major NASA (Acronyms are provided in Appendix A.) led multi-partner atmospheric field campaign completed in the spring of 2006 ( http://cloud1.arc.nasa.gov/intex-b/ ). Its major objectives aimed at (i) investigating the extent and persistence of the outflow of pollution from Mexico; (ii) understanding transport and evolution of Asian pollution and implications for air quality and climate across western North America; and (iii) validating space-borne observations of tropospheric composition. INTEX-B was performed in two phases. In its first phase (1–21 March), INTEX-B operated as part of the MILAGRO campaign with a focus on observations over Mexico and the Gulf of Mexico. In the second phase (17 April–15 May), the main INTEX-B focus was on trans-Pacific Asian pollution transport. Multiple airborne platforms carrying state of the art chemistry and radiation payloads were flown in concert with satellites and ground stations during the two phases of INTEX-B. Validation of Aura satellite instruments (TES, OMI, MLS, HIRDLS) was a key objective within INTEX-B. Satellite products along with meteorological and 3-D chemical transport model forecasts were integrated into the flight planning process to allow targeted sampling of air parcels. Inter-comparisons were performed among and between aircraft payloads to quantify the accuracy of data and to create a unified data set. Pollution plumes were sampled over the Gulf of Mexico and the Pacific several days after downwind transport from source regions. Signatures of Asian pollution were routinely detected by INTEX-B aircraft, providing a valuable data set on gas and aerosol composition to test models and evaluate pathways of pollution transport and their impact on air quality and climate. This overview provides details about campaign implementation and a context within which the present and future INTEX-B/MILAGRO publications can be understood.
TL;DR: In this article, the authors report the results and analysis of a recent field campaign in August 2007 investigating the impacts of emissions from transportation on air quality and community concentrations in Beijing, China.
TL;DR: Increasing the ventilation rate by means of a mechanical system and the use of low-emission furnishings can play key roles in improving the indoor air quality within schools.
TL;DR: Concentrations of PM were not only higher during the wildfire episodes, but the PM was much more toxic to the lung on an equal weight basis than was PM collected from normal ambient air in the region.
Abstract: BackgroundDuring the last week of June 2008, central and northern California experienced thousands of forest and brush fires, giving rise to a week of severe fire-related particulate air pollution ...
TL;DR: In this paper, the authors proposed a smoke modeling framework called BlueSky, which links together a variety of state-of-the-art models of meteorology, fuels, consumption, emissions, and air quality.
Abstract: Smoke from fire is a local, regional and often international issue that is growing in complexity as competition for airshed resources increases. BlueSky is a smoke modeling framework designed to help address this problem by enabling simulations of the cumulative smoke impacts from fires (prescribed, wildland, and agricultural) across a region. Versions of BlueSky have been implemented in prediction systems across the contiguous US, and land managers, air-quality regulators, incident command teams, and the general public can currently obtain BlueSky-based predictions of smoke impacts for their region. A highly modular framework, BlueSky links together a variety of state-of-the-art models of meteorology, fuels, consumption, emissions, and air quality, and offers multiple model choices at each modeling step. This modularity also allows direct comparison between similar component models. This paper presents the overall model framework Version 2.5 - the component models, how they are linked together, and the results from case studies of two wildfires. Predicted results are affected by the specific choice of modeling pathway. With the pathway chosen, the modeled output generally compares well with plume shape and extent as observed by satellites, but underpredicts surface concentrations as observed by ground monitors. Sensitivity studies show that knowledge of fire behavior can greatly improve the accuracy of these smoke impact calculations.
TL;DR: The growth of megacities greatly aggravates the health impacts of polluted air, yet it may also provide an opportunity to mitigate climate change, if implemented air quality policies are designed to also reduce global warming.
Abstract: As of 2008, over half of humanity lives in cities. The number of megacities (with populations over 10 million) grew from 3 in 1975 to 19 in 2007, and is projected to increase to 27 in 2025 ( 1 ). These megacities are the engines of growing economies, but are also very large sources of air pollutants and climate-forcing agents. The growth of megacities greatly aggravates the health impacts of polluted air, yet it may also provide an opportunity to mitigate climate change, if implemented air quality policies are designed to also reduce global warming.
TL;DR: In this article, a series of aggressive measures was launched by the Chinese government to reduce pollutant emissions from Beijing and surrounding areas during the Olympic Games and showed significant decreases in concentrations of O3, CO, NOy, and SO2 during August 2008, relative to August 2006-2007.
Abstract: . A series of aggressive measures was launched by the Chinese government to reduce pollutant emissions from Beijing and surrounding areas during the Olympic Games. Observations at Miyun, a rural site 100 km downwind of the Beijing urban center, show significant decreases in concentrations of O3, CO, NOy, and SO2 during August 2008, relative to August 2006–2007. The mean daytime mixing ratio of O3 was lower by about 15 ppbv, reduced to 50 ppbv, in August 2008. The relative reductions in daytime SO2, CO, and NOy were 61%, 25%, and 21%, respectively. Changes in SO2 and in species correlations from 2007 to 2008 indicate that emissions of SO2, CO, and NOx were reduced at least by 60%, 32%, and 36%, respectively, during the Olympics. Analysis of meteorological conditions and interpretation of observations using a chemical transport model suggest that although the day-to-day variability in ozone is driven mostly by meteorology, the reduction in emissions of ozone precursors associated with the Olympic Games had a significant contribution to the observed decrease in O3 during August 2008, accounting for 80% of the O3 reduction for the month as a whole and 45% during the Olympics Period (8–24 August). The model predicts that emission restrictions such as those implemented during the Olympics can affect O3 far beyond the Beijing urban area, resulting in reductions in boundary layer O3 of 2–10 ppbv over a large region of the North China Plain and Northeastern China.
TL;DR: In this paper, the effect of flue gas desulfurization (FGD) and phasing out small inefficient units in the power sector in order to achieve the national goal of 10% reduction in sulfur dioxide (SO2) emissions from 2005 to 2010 was explored.
Abstract: Facing challenges of increased energy consumption and related regional air pollution, China has been aggressively implementing flue gas desulfurization (FGD) and phasing out small inefficient units in the power sector in order to achieve the national goal of 10% reduction in sulfur dioxide (SO2) emissions from 2005 to 2010. In this paper, the effect of these measures on soil acidification is explored. An integrated methodology is used, combining emission inventory data, emission forecasts, air quality modeling, and ecological sensitivities indicated by critical load. National emissions of SO2, oxides of nitrogen (NOX), particulate matter (PM), and ammonia (NH3) in 2005 were estimated to be 30.7, 19.6, 31.3, and 16.6 Mt, respectively. Implementation of existing policy will lead to reductions in SO2 and PM emissions, while those of NOX and NH3 will continue to rise, even under tentatively proposed control measures. In 2005, the critical load for soil acidification caused by sulfur (S) deposition was exceede...
01 Dec 2009
TL;DR: The exceedance of the critical load for nitrogen (N, combining effects of eutrophication and acidification) will double from 2005 to 2020 due to increased NO(X) and NH(3) emissions, combining the acidification effects of S and N, the benefits of SO(2) reductions during 2005-2010 will almost be negated by increased N emissions.
Abstract: Facing challenges of increased energy consumption and related regional air pollution, China has been aggressively implementing flue gas desulfurization (FGD) and phasing out small inefficient units in the power sector in order to achieve the national goal of 10% reduction in sulfur dioxide (SO2) emissions from 2005 to 2010. In this paper, the effect of these measures on soil acidification is explored. An integrated methodology is used, combining emission inventory data, emission forecasts, air quality modeling, and ecological sensitivities indicated by critical load. National emissions of SO2, oxides of nitrogen (NOX), particulate matter (PM), and ammonia (NH3) in 2005 were estimated to be 30.7, 19.6, 31.3, and 16.6 Mt, respectively. Implementation of existing policy will lead to reductions in SO2 and PM emissions, while those of NOX and NH3 will continue to rise, even under tentatively proposed control measures. In 2005, the critical load for soil acidification caused by sulfur (S) deposition was exceede...
United States Environmental Protection Agency1, University of Illinois at Urbana–Champaign2, Carnegie Mellon University3, California Department of Fish and Wildlife4, National Research Council5, University of California, Berkeley6, National Center for Atmospheric Research7, Pacific Northwest National Laboratory8, University at Albany, SUNY9, Science Applications International Corporation10, Harvard University11, Columbia University12, Desert Research Institute13, Washington State University14, United States Department of Agriculture15, Georgia Institute of Technology16, University of Washington17, University of Patras18, Foundation for Research & Technology – Hellas19, Goddard Institute for Space Studies20, Konkuk University21, National Center for Supercomputing Applications22
TL;DR: In this article, the authors provide a synthesis of results that have emerged from recent modeling studies of the potential sensitivity of U.S. regional ozone (O3) concentrations to global climate change (ca. 2050).
Abstract: This paper provides a synthesis of results that have emerged from recent modeling studies of the potential sensitivity of U.S. regional ozone (O3) concentrations to global climate change (ca. 2050). This research has been carried out under the auspices of an ongoing U.S. Environmental Protection Agency (EPA) assessment effort to increase scientific understanding of the multiple complex interactions among climate, emissions, atmospheric chemistry, and air quality. The ultimate goal is to enhance the ability of air quality managers to consider global change in their decisions through improved characterization of the potential effects of global change on air quality, including O3 The results discussed here are interim, representing the first phase of the EPA assessment. The aim in this first phase was to consider the effects of climate change alone on air quality, without accompanying changes in anthropogenic emissions of precursor pollutants. Across all of the modeling experiments carried out by the differe...
TL;DR: In this paper, an artificial neural network (ANN) framework was proposed to reduce the uncertainty of surface PM estimation from satellite data, using 3 years of MODIS optical thickness data at 0.55 μm and meteorological analyses from the rapid update cycle to estimate surface level PM2.5.
Abstract: [1] In recent years, sparse, surface-based air quality monitoring has been improved by using wide-swath, satellite-derived aerosol products. However, satellites are sensitive to the entire aerosol column, not only the aerosol near the surface that impacts human health. In part 1 of this series, we used multiple regression to demonstrate how inclusion of meteorological analyses can help constrain the surface level proportion of the aerosol profile and improve the estimate of surface PM2.5. Here, instead of multiple regression technique, we describe an artificial neural network (ANN) framework that reduces the uncertainty of surface PM estimation from satellite data. We use 3 years of MODIS aerosol optical thickness data at 0.55 μm and meteorological analyses from the rapid update cycle to estimate surface level PM2.5 over the southeast United States (EPA region 4). As compared to regression coefficients obtained through simple correlation (R = 0.60) or multiple regression (R = 0.68) techniques, the ANN derives hourly PM2.5 data that compare with observations with R = 0.74. For estimating daily mean PM2.5, the ANN techniques results in correlation of R = 0.78. Although the degree of improvement varies over different sites and seasons, this study demonstrates the potential for using ANN for operational air quality monitoring.