Showing papers on "Air pollutant concentrations published in 2012"

Air quality management in China: issues, challenges, and options

Abstract: This article analyzed the control progress and current status of air quality, identified the major air pollution issues and challenges in future, proposed the long-term air pollution control targets, and suggested the options for better air quality in China. With the continuing growth of economy in the next 10-15 years, China will face a more severe situation of energy consumption, electricity generation and vehicle population leading to increase in multiple pollutant emissions. Controlling regional air pollution especially fine particles and ozone, as well as lowering carbon emissions from fossil fuel consumption will be a big challenge for the country. To protect public health and the eco-system, the ambient air quality in all Chinese cities shall attain the national ambient air quality standards (NAAQS) and ambient air quality guideline values set by the World Health Organization (WHO). To achieve the air quality targets, the emissions of SO2, NOx, PM10, and volatile organic compounds (VOC) should decrease by 60%, 40%, 50%, and 40%, respectively, on the basis of that in 2005. A comprehensive control policy focusing on multiple pollutants and emission sources at both the local and regional levels was proposed to mitigate the regional air pollution issue in China. The options include development of clean energy resources, promotion of clean and efficient coal use, enhancement of vehicle pollution control, implementation of synchronous control of multiple pollutants including SO2, NOx, VOC, and PM emissions, joint prevention and control of regional air pollution, and application of climate friendly air pollution control measures.

Ambient Air Pollution and the Risk of Stillbirth

Abstract: The purpose of the present study was to examine the risk of stillbirth associated with ambient air pollution during pregnancy. Using live birth and fetal death data from New Jersey from 1998 to 2004, the authors assigned daily concentrations of air pollution to each birth or fetal death. Generalized estimating equation models were used to estimate the relative odds of stillbirth associated with interquartile range increases in mean air pollutant concentrations in the first, second, and third trimesters and throughout the entire pregnancy. The relative odds of stillbirth were significantly increased with each 10-ppb increase in mean nitrogen dioxide concentration in the first trimester (odds ratio (OR) = 1.16, 95% confidence interval (CI): 1.03, 1.31), each 3-ppb increase in mean sulfur dioxide concentration in the first (OR = 1.13, 95% CI: 1.01, 1.28) and third (OR = 1.26, 95% CI: 1.03, 1.37) trimesters, and each 0.4-ppm increase in mean carbon monoxide concentration in the second (OR = 1.14, 95% CI: 1.01, 1.28) and third (OR = 1.14, 95% CI: 1.06, 1.24) trimesters. Although ambient air pollution during pregnancy appeared to increase the relative odds of stillbirth, further studies are needed to confirm these findings and examine mechanistic explanations.

Primary NO2 emissions and their impact on air quality in traffic environments in Germany

Abstract: The decreasing NOX concentrations at urban measurement stations in Germany are in agreement with the reduction of NOX emissions from vehicular traffic. However, the measured NO2 concentrations are stagnating nationwide. In 2010, at more than the half of the urban measurement stations in Germany, annual mean values for NO2 exceeded the new Europe-wide limit value of 40 μg/m3 (20 ppbv) NO2. Similar findings are reported from many other member states of the European Union. The observed trend of the airborne NO2 concentrations has different reasons. Firstly, the NO2/NOx emission ratio has increased significantly during the last two decades. Furthermore, secondary NO2, caused by the titration reactions of NO with ozone (O3) and peroxy radicals (RO2), is responsible for the major fraction (approximately 70%) of the measured NO2. However, secondary NO2 shows a highly nonlinear dependency on NOx and thus, is decreasing much more slowly than expected from the decreasing NOx levels. Based on the results from the present study, the increased NO2/NOX emission ratio can only explain a minor fraction of the observed high airborne NO2 concentration in the city center. A further reduction of primary NO2 emissions, due to improved exhaust gas treatment, will not have a strong influence on urban NO2 levels, and a further significant reduction of the NOX emissions, in particular from vehicular traffic, is necessary in order to meet the annual mean limit value for NO2 of about 20 ppb in the future.

Analysis of the air pollution climate at a background site in the Po valley

Abstract: The Po valley in northern Italy is renowned for its high air pollutant concentrations. Measurements of air pollutants from a background site in Modena, a town of 200 thousand inhabitants within the Po valley, are analysed. These comprise hourly data for CO, NO, NO2, NOx, and O3, and daily gravimetric equivalent data for PM10 from 1998–2010. The data are analysed in terms of long-term trends, annual, weekly and diurnal cycles, and auto-correlation and cross-correlation functions. CO, NO and NO2 exhibit a strongly traffic-related pattern, with daily peaks at morning and evening rush hour and lower concentrations over the weekend. Ozone shows an annual cycle with a peak in July due to local production; notwithstanding the diurnal cycle dominated by titration by nitrogen oxide, the decreasing long term trend in NO concentration did not affect the long term trend in O3, whose mean concentration remained steady over the sampling period. PM10 shows a strong seasonality with higher concentration in winter and lower concentration in summer and spring. Both PM10 and ozone show a marked weekly cycle in summer and winter respectively. Regressions of PM10 upon NOx show a consistently greater intercept in winter, representing higher secondary PM10 in the cooler months of the year. There is a seasonal pattern in primary PM10 to NOx ratios, with lower values in winter and higher values in summer, but the reasons are unclear.

Review of Singapore's air quality and greenhouse gas emissions: Current situation and opportunities

Abstract: Singapore has many environmental accomplishments to its credit. Accessible data on air quality indicates that all criteria pollutants satisfy both U.S. Environmental Protection Agency (EPA) and Wor...

Mobile Air Monitoring: Measuring Change in Air Quality in the City of Hamilton, 2005–2010

Abstract: This paper examines the change in air pollutant concentrations between 2005 and 2010 occurring in the City of Hamilton, Ontario, Canada. After analysis of stationary air pollutant concentration data, we analyze mobile air pollutant concentration data. Air pollutants included in the analysis are CO, PM2.5, SO2, NO, NO2, and NOX. Stationary monitoring indicates a continuous reduction in air pollutant concentrations. Stationary monitors only cover a small spatial extent of Hamilton. Mobile monitoring of air pollutant concentrations, averaged over census tract boundaries, indicates both improvement and decline in air quality. These improvements and declines in air quality are spatially clustered throughout Hamilton. Mobile data indicated significant decline in median pollutant concentration for CO, SO2, PM2.5, and NO2; but significant increase for NO and NOX. Air quality change in Hamilton is spatially heterogeneous, and is not captured based on the current stationary monitoring network. Coupling of mobile and stationary air pollutant concentration monitoring provides a more accurate spatial assessment of local air quality.

Review of urban air quality in Sub-Saharan Africa region - air quality profile of SSA countries

Abstract: In Africa, urban outdoor air pollution is responsible for an estimated 49,000 premature deaths annually with indoor use of solid fuels being responsible for eight times this value, the main burden being borne by Sub Saharan African countries. Air pollution, outdoor and indoor, affects the health and life chances of millions of people in Sub Saharan Africa (SSA)every day. There is a link between air pollution and poverty since poor people are exposed to higher concentrations of air pollutants and tend to suffer disproportionately from the effects of deteriorating air quality (AQ). Children in cities exposed to high concentrations of air pollutants will more often develop respiratory ailments which prevent them from developing and learning well. As a consequence they will suffer in adult life from low levels of qualifications and skills. The implication of poorly educated children is not only a reduction of quality of their lives but also an obstacle for the economic development of a country as a whole. Rapid urbanization means increase in motorization and economic activity which in turn leads to increased air pollution if countermeasures are not taken. In view these linkages addressing urban AQ in SSA is particularly important. Air pollution in Sub Saharan cities appears to be on the rise with respect to many key pollutants. In some cities where monitoring has been performed levels of air pollution exceed World Health Organization recommended guidelines. The main cause of urban air pollution is the use of fossil fuels in transport, power generation, industry and domestic sectors. In addition, the burning of firewood, agricultural and animal waste also contributes to pollution levels. Pollutant emissions have direct and indirect effects with a wide range of impacts on human health, ecosystems, agriculture and materials. There is a growing need to determine the state of urban AQ and the challenges posed to solve it and identify the most effective measures to protect human health and the environment. Learning from experience and successes in urban AQ management (AQM) from other countries can assists in the formulation and implementation of strategies to achieve better AQ in Sub Saharan Africa. This report compiles the information provided by the 25countries in a harmonized way and gives an in-depth review of AQ in SSA with AQ profile of each country, presenting the country's main current urban AQ issues, emissions standards, ongoing projects, lessons learned from good/bad practices. It was attempted to compile this information also for additional SSA countries from available publications and internet sources.

Mixing layer height and air pollution levels in urban area

Abstract: Ceilometers are applied by KIT/IMK-IFU to detect layering of the lower atmosphere continuously. This is necessary because not only wind speed and direction but also atmospheric layering and especially the mixing layer height (MLH) influence exchange processes of ground level emissions. It will be discussed how the ceilometer monitoring information is used to interpret the air pollution near the ground. The information about atmospheric layering is continuously monitored by uninterrupted remote sensing measurements with the Vaisala ceilometer CL51 which is an eye-safe commercial mini-lidar system. Special software for this ceilometer provides routine retrievals of lower atmosphere layering from vertical profiles of laser backscatter data. An intensive measurement period during the winter 2011/2012 is studied. The meteorological influences upon air pollutant concentrations are investgated and the correlations of air pollutant concentrations with ceilometer MLH are determined. Benzene was detected by department of Applied Climatology and Landscape Ecology, University of Duisburg-Essen (UDE) with a gas chromatograph during the measurement period. The meteorological data are collected by UDE and the monitoring station Essen of the German national meteorological service DWD. The concentrations of the air pollutants NO, NO 2 and PM 10 are provided by the national air pollution network LANUV.

Long Term Variations of the Atmospheric Air Pollutants in Istanbul City

Abstract: High population density and intense industrial activity has resulted in various forms of pollution in megacities. Air pollution ranks at the top of this list. This study investigated long-term changes in air pollutant parameters (SO2, CO, NO, NO2, NOx) in Istanbul City, Turkey, using data from air-quality measurement stations on the Asian and European sides of Istanbul. The results show decreases from 2002 to 2010 in the amounts of SO2 (one of the main pollutants released as a result of the burning of fossil fuels) and CO (indicative of incomplete combustion). However, NOx concentrations showed fluctuations over time, rather than a steady decline throughout the study period.

Integrated assessment of air pollution in tehran, over the period from september 2008 to september 2009.

Abstract: Air pollution is a major problem in urban\industrial areas, like Tehran, and has several impacts on human health. This study aimed at assessing concentrations of criteria air pollutants (CO, SO2, NO2, O3, PM10) in Tehran, ex- tracting patterns of hourly, daily, weekly, and monthly variations of concentration s, and making comparisons to Na- tional Standards and WHO Guidelines. Methods: Air quality data were taken from Air Quality Control Corporation and 5 sampling stations (out of 13) were selected for analysis according to data availability. Microsoft Excel 2003 was used for data analysis and plotting the charts. Results: Patterns of temporal variation (hourly, daily, weekly, and monthly) of air pollutant concentrations were ex- tracted. In some cases extracted patterns matched with the patterns proposed by other researchers. Pollutant concentra- tions were compared to National Standards and WHO Guidelines and it was observed that in most of the days, we ex- ceeded the limit values. Conclusion: Air pollution in Tehran is quite high and there are many days that we exceed the standards; therefore ap- propriate control strategies are needed. Although the number of sampling stations is high enough to be representative of whole city, it is proposed that an independent sampling station is setup to check the validity of the measurements.

Effects of Engine Idling on National Ambient Air Quality Standards Criteria Pollutant Emissions from Nonroad Diesel Construction Equipment

Abstract: It is difficult to assess the effects of engine idling on air pollutant emissions from highway construction equipment because of a lack of combined activity and emissions data. A methodology is presented for quantifying the impact of idling on National Ambient Air Quality Standards criteria pollutant emissions, including nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC), and particulate matter (PM). The methodology and results are based on field data collected from 35 items of nonroad diesel construction equipment. Engine idle time was quantified in terms of equipment operational efficiency (η), which was defined as the ratio of nonidle time to total equipment use time (nonidle time plus idle time). With η and the ratio of idle to nonidle emission rates (re) for each pollutant, the percentage increase in the total quantities of each pollutant emitted (NE) was calculated for each item of equipment for the observed values of η and re. Results showed that as η increased (or idle time decreased),...

Validation of a novel air toxic risk model with air monitoring.

Abstract: Three modeling systems were used to estimate human health risks from air pollution: two versions of MNRiskS (for Minnesota Risk Screening), and the USEPA National Air Toxics Assessment (NATA). MNRiskS is a unique cumulative risk modeling system used to assess risks from multiple air toxics, sources, and pathways on a local to a state-wide scale. In addition, ambient outdoor air monitoring data were available for estimation of risks and comparison with the modeled estimates of air concentrations. Highest air concentrations and estimated risks were generally found in the Minneapolis-St. Paul metropolitan area and lowest risks in undeveloped rural areas. Emissions from mobile and area (nonpoint) sources created greater estimated risks than emissions from point sources. Highest cancer risks were via ingestion pathway exposures to dioxins and related compounds. Diesel particles, acrolein, and formaldehyde created the highest estimated inhalation health impacts. Model-estimated air concentrations were generally highest for NATA and lowest for the AERMOD version of MNRiskS. This validation study showed reasonable agreement between available measurements and model predictions, although results varied among pollutants, and predictions were often lower than measurements. The results increased confidence in identifying pollutants, pathways, geographic areas, sources, and receptors of potential concern, and thus provide a basis for informing pollution reduction strategies and focusing efforts on specific pollutants (diesel particles, acrolein, and formaldehyde), geographic areas (urban centers), and source categories (nonpoint sources). The results heighten concerns about risks from food chain exposures to dioxins and PAHs. Risk estimates were sensitive to variations in methodologies for treating emissions, dispersion, deposition, exposure, and toxicity.

Combination of artificial neural network models for air quality predictions for the region of Annaba, Algeria

Abstract: This paper describes the development of a global air quality prediction model based on the combination of five different pollutants predicted values; specifically: O3, PM10, SO2, NOx and COx. Each pollutant concentration prediction is obtained from a radial basis function (RBF) neural network developed in order to predict 12 hours ahead the five air pollutant parameters for the region of Annaba, northeastern Algeria. Given the measurement of air pollutant concentration and three chosen metrological parameters (wind speed, temperature and humidity) at time t, the models can predict the air pollutant concentrations at t+12 hours. Once these concentrations are obtained, a second artificial neural network (ANN) given by a multi-layered perceptron (MLP) is used to combine them and forecast the air quality over a scale ranging from 1 for very good to 5 for very bad.

The harmful effects of diesel engine exhaust emissions

Abstract: With the increase in the number of engine vehicles, air pollution is also increasing quickly; and with the increase in air pollution, all living conditions are affected in a negative way. Diesel engines also cause air pollution, which adversely affects human health and is becoming a permanent problem. A single-cylinder diesel engine was used in this work; the exhaust gas emissions, in different speed ranges, were investigated. These emissions are carbon monoxide emissions (CO), nitrogen oxides (NOx), oxygen (O2), and carbon dioxide (CO2). The amount of the changes in emissions was evaluated in terms of air pollution with graphics.

Twenty-Year Road Traffic Emissions Trend in Greece

Abstract: Air pollutants emissions from traffic are very closely connected to urban air quality, in a local scale, as well as to global problems like climate change, in a large scale. Road transport air pollutants emissions represent, in most cases, a critical parameter for a comprehensive and successful understanding of the mechanisms governing the air pollutants concentrations. Hence, reliable estimations and comprehension of road transport emissions are indispensable in order to set reliable strategies in the direction of air pollution abatement and management of air pollutants and greenhouse gases emissions. In this framework, in the present work, the emissions of air pollutants from road transport in Greece will be presented for the whole period 1990–2009 as it was found that a detailed, accurate and reliable emissions inventory was missing. The whole period emissions variation has clarified the impact of the change in the vehicle fleet, the engine technologies and the fuel quality. The calculated results have revealed that the age of the vehicles and the corresponding engine technology are the critical parameters determining the amount of the pollutants emitted. This was mainly observed in both passenger cars and heavy duty vehicles demonstrating the importance of a renewal programme of the old circulating vehicles in order to set an effective air pollution abatement strategy. Passenger cars were found to be responsible for the major part of most air pollutants emissions except from nitrogen oxides and particulates emissions. Heavy duty vehicles contribute more than 66% to nitrogen oxides and particulates emissions. For the whole time period, all calculated pollutants present a decreasing trend, with the exception of carbon dioxide and nitrous oxide which increase constantly, ranging from −96% for sulphur dioxide to −1% for PM10.

Indoor and Outdoor Relationships of Respirable Suspended Particulate Matter at Primary Schools in Kuala Terengganu, Malaysia:

Abstract: Studies have found that indoor air pollution affects human, especially children and the elderly, more compared to ambient atmospheric air. This study aims to investigate respirable suspended particulate matter (RSP) concentration in selected primary schools with different surrounding human activities, and to establish statistical relationships between indoor and outdoor air pollutant concentrations in each selected schools in Kuala Terengganu. Failure to identify and establish indoor air pollution status can increase health problems for these young students and degrade their learning environment and comfort. Indoor air quality (IAQ) parameters in seven primary schools were conducted during the monsoon season of August 2008 until March 2009. Ineach classroom, RSP, air velocity, relative humidity and temperature were monitored during school hours, and a complete walkthrough survey was completed. Results show a statistically significant difference for the six IAQ parameters between the seven schools at the 9...

Experimental studies of the dilution of vehicle exhaust pollutants by environment-protecting pervious pavement.

Abstract: This study determines whether environment-protecting pervious pavement can dilute pollutants immediately after emissions from vehicle. The turbulence-driven dry-deposition process is too slow to be considered in this aspect. The pavement used is the JW pavement (according to its inventors name), a high-load-bearing water-permeable pavement with patents in over 100 countries, which has already been used for more than 8 years in Taiwan and is well suited to replacing conventional road pavement, making the potential implementation of the study results feasible. The design of this study included two sets of experiments. Variation of the air pollutant concentrations within a fenced area over the JW pavement with one vehicle discharging emissions into was monitored and compared with results over a non-JW pavement. The ambient wind speed was low during the first experiment, and the results obtained were highly credible. It was found that the JW pavement diluted vehicle pollutant emissions near the ground surface by 40%-87% within 5 min of emission; whereas the data at 2 m height suggested that about 58%-97% of pollutants were trapped underneath the pavement 20 min after emission. Those quantitative estimations may be off by +/- 10%, if errors in emissions and measurements were considered. SO2 and CO2 underwent the most significant reduction. Very likely, pollutants were forced to move underneath due to the special design of the pavement. During the second experiment, ambient wind speeds were high and the results obtained had less credibility, but they did not disprove the pollutant dilution capacity of the JW pavement. In order to track the fate of pollutants, parts of the pavement were removed to reveal a micro version of wetland underneath, which could possibly hold the responsibility of absorbing and decomposing pollutants to forms harmless to the environment and human health.

The public health benefits of air pollution control.

Abstract: The US Congress is currently engaged in a debate regarding restriction of Environmental Protection Agency (EPA) authority under the Clean Air Act The discussion has been focused on the cost to business to complywith the CleanAir Act and the potential negative effect on employment As heath care professionals, we believe it is necessary to review some of the facts since the Clean AirActwas initiated and the role of theCleanAirAct in the future In the past year, the House of Representatives has passed a number of bills that would stop, delay, or weaken the EPA rules issued under the authority of the Clean Air Act The House has passed legislation that would prevent or delay clean up of emissions from cement kilns, coarse particulate matter pollution, industrial boilers, mercury and toxic pollutants from power plants, and pollution from power plants that blow across state borders to neighboring downwind states Additionally, the House has passed legislation that would subject all future EPA/Clean Air Act rules to a cost/benefit assessment that is heavily tilted in favor of the regulated industry Why is the House engaged in this attack on the Clean Air Act? Opponents of the EPA have portrayed the agency as a prime example of government overreach and a bureaucratic agency run amok Opponents of the EPA say the rules are ‘‘job-destroying regulations’’ that create regulatory uncertainty and hurt the overall US economy Supporters of the EPA counter that complying with the Clean Air Act rules will create new jobs, largely in sectors that install and maintain pollution control equipment What is missing from the discussion are the health effects of air pollution and the potential health gains that can be made by reducing air pollution We believe that an analysis of available health and economic data show that air pollution standards have significant net benefits for our society at large There is compelling evidence that air pollution has severe adverse health effects, particularly for respiratory health Several

Air pollution in Reykjavík and dispensation of drugs for angina pectoris

Abstract: Introduction: Ambient air pollution is associated with increase in morbidity from heart diseases. Air pollutant concentrations in the Reykjavik area are known to exceed official European health limits several times every year. Objectives: To evaluate the association between ambient air concentration of NO 2 , O 3 , PM 10 , and H 2 S in Iceland9s capital area Reykjavik and the dispensation of drugs for angina pectoris. Methods: Data on the daily dispensing of drugs for angina pectoris were obtained from The Icelandic Medicine Registry. Data on hourly concentrations of NO 2 , O 3 , PM 10 , and H 2 S were obtained from The City of Reykjavik, and The Environment Agency of Iceland. A case-crossover design was used and the study period was January 1st 2005 to December 31st 2009. Results: Exposure to air pollution was associated with the dispensing of drugs for cardiovascular disease (C01DA). For every 10 μg/m 3 increase of NO 2 concentration levels the dispensing of glyceril trinitrates (sub-group C01DA02) increased by 11.6% (at lag 0) and 7.1% (at lag 1). Similarly, an increae by 10 μg/m 3 of O 3 concentration was associated with 9.0% (at lag 0) and 7.2% (at lag 1) increase in glyceril trinitrate dispensations. Conclusion: The findings indicate that increased air pollution levels are associated with increased dispensation of glyceril trinitrate. We caution that this is the first study to examine the association between ambient air pollution and dispensation of drugs for angina pectoris, hence further evidence is needed for definite conclusions of this association. Drug dispensing may potentially be a sensitive indicator of health when estimating the effects of air pollution.

In-Vehicle Air Pollution Exposure Measurement and Modeling

Abstract: On-road concentrations of traffic-related pollutants are typically much higher than concentrations measured at ambient monitoring stations. This results in in-vehicle microenvironments contributing disproportionately to the total exposure with exposures frequently being as high as on-road concentrations. However, under conditions of low air exchange rate, pollutants with significant in-vehicle losses, such as particles, can have in-vehicle concentrations that are significantly lower than those outside the vehicle. The authors tested a large sample of vehicles selected to be representative of the California fleet for air exchange rate (AER) at various speeds and found that AER is a predictable function of vehicle age or mileage, speed, and ventilation setting choice (outside air, recirculation, or open windows). The authors demonstrated that AER is the dominant factor in determining the inside-to-outside ratio for pollutants like ultrafine particles. Models were developed that explain over 79% of the variability in AER and ultrafine particle indoor/outdoor ratios across the California fleet and across the expected range of normal driving conditions. To better determine on-road concentrations, the authors also conducted extensive on-road measurements using a mobile platform hybrid vehicle with real-time instrumentation. Models were developed and validated to estimate on-road traffic-related pollutant concentrations (variance explained was 37% to 73% depending on the air pollutant and modeling method). Models developed in this study can be combined with subject information about their vehicle, ventilation choices, and commute route to estimate in-vehicle exposures in future studies.

Air pollution in a street canyon estimated considering different parameterisations of vehicle-induced turbulence

Abstract: Leeward air pollutant concentrations (C) are estimated by incorporating four parameterisations of traffic-produced turbulence (TPT) into the scaling of C inside a street canyon. Three parameterisations consider expressions previously introduced by other authors, based on a theoretical formulation of TPT and a semi-empirical approach already incorporated in an operational street model. The fourth scheme introduces an empirical expression of TPT derived from four full-scale street canyon datasets. Hourly NO x concentrations are calculated for an asymmetric street canyon in Buenos Aires, using meteorological observations at local airport and modelled background concentrations. Statistical indicators show that the performance of the four schemes is satisfactory.

ANN and Fuzzy c-Means applied to environmental pollution prediction

Abstract: Salamanca, situated in center of Mexico is among the cities which suffer most from the air pollution in Mexico. The vehicular park and the industry, as well as orography and climatic characteristics have propitiated the increment in pollutant concentration of Sulphur Dioxide (SO 2 ). In this work, a Multilayer Perceptron Neural Network has been used to make the prediction of an hour ahead of pollutant concentration. A database used to train the Neural Network corresponds to historical time series of meteorological variables and air pollutant concentrations of SO 2 . Before the prediction, Fuzzy c-Means and K-means clustering algorithms have been implemented in order to find relationship among pollutant and meteorological variables. Our experiments with the proposed system show the importance of this set of meteorological variables on the prediction of SO 2 pollutant concentrations and the neural network efficiency. The performance estimation is determined using the Root Mean Square Error (RMSE) and Mean Absolute Error (MAE). The results showed that the information obtained in the clustering step allows a prediction of an hour ahead, with data from past 2 hours.

Impact of the Transboundary Transport of Air Pollutants on Air Quality in Spain

Abstract: Although compliance with the European limit values for air pollutants has been achieved over large parts in Spain, some challenges remain for O3 on the maximum daily 8-hour mean and information limit values, for particulate matter on the PM10 annual and daily limit values and for NO2 on annual and hourly limit values. Transboundary transport of air pollutants has started to be recognized as a mechanism affecting air quality. Nevertheless, as a consequence of the complexity of atmospheric chemistry it is not easy to determine the importance of this effect. Photochemical models constitute an adequate tool to address this challenge, allowing the identification of pollutant pathways and the quantifi- cation of the influence of long-range transport of air pollutants. In this paper we evaluate the influence of out-of-Spain emissions on this non-compliance picture by using the CHIMERE photochemical model. For this purpose the model was run at a 0.2?-horizontal resolution for a European domain. Although at this resolution not all the local effects can be captured, transboundary transport of air pollutants can be examined. Several simulations were performed considering different emission scenarios. To see all out-of-Spain emissions influence, all the emissions were set to zero, excepting those in Spain. This includes examining European and ships effects on air quality in Spain. A second simulation was performed setting to zero just European-countries emissions, to see the effect of Europe. The third and fourth simulations were carried out by setting to zero France and Portugal emissions respectively. Ozone has been found to be the pollutant more affected by this transboundary transport, in particular in the summer period. The model indicates that the incoming air masses contributed in 2009 to the non-compliance with the European normative regulating the maximum daily 8-hour mean.

From Olympians to mere mortals: the indiscriminate, global challenges of air pollution.

Abstract: Beijing won its bid to host the 2008 Olympics while promising to substantially improve its air quality, spending in excess of 10 billion dollars to implement pollution control measures (1). Based on substantial and growing evidence that air pollution impacts cardiac and respiratory health (2), Olympic athletes and the public were concerned that notoriously poor air quality in Beijing might have detrimental impacts on athletes. Even after substantive (13–60%) reductions in individual air pollutant concentrations during the 2008 Games as reported in this issue of the Journal (pp. 1150–1159) by Huang and colleagues (3), daily average levels of pollutants such as fine particulate matter in Beijing remained four to nine times higher than in large metropolitan cities in the United States during the same time period (4). Athletes remained concerned about potential health impacts, some deferred competing in the Games (5), and Olympic teams set up training camps away from Beijing to avoid intense air pollution exposures (6). Over several years just prior to the 2008 Olympics, epidemiological studies reported that patterns of associations between fine particulate air pollution and cause-specific mortality were consistent with the hypothesis that air pollution exposure contributes to pulmonary and systemic oxidative stress, inflammation, and associated increased risk of atherosclerosis and ischemic cardiovascular and obstructive pulmonary diseases (2, 7). Recent reviews of the expanding literature (8) and emerging evidence from the Multi-Ethnic Study of Atherosclerosis (9) suggest that there are likely multiple, complex, interdependent mechanistic pathways linking air pollution to cardiopulmonary disease, but also provide growing evidence that pulmonary and systemic oxidative stress and inflammation play important roles. Against this backdrop, in this issue of the Journal, Huang and coworkers (pp. 1150–1159) report results of a Beijing Olympics–based study investigating the relationship between air pollution and exhaled breath and urinary biomarkers of pulmonary and systemic oxidative stress and inflammation (3). This quasiexperimental study evaluated 125 young and healthy medical students before, during, and after the 2008 Beijing Olympics. Huang and colleagues demonstrated substantial decreases in these biomarkers tracking with reductions in air pollution, followed by subsequent increases in these biomarkers after return toward typical levels of air pollution in Beijing. These results add to previously reported evidence, from the same research team, that these Olympics-related changes in air pollution in Beijing were also associated with changes in systemic inflammation, thrombosis, blood pressure, and heart rate (10). Also, a third study using the Beijing Olympics–related changes in air pollution (with a focus on black carbon) found that the reductions in air pollution were also associated with exhaled nitric oxide, a biomarker of acute respiratory inflammation (11). These studies have several important strengths. For example, Huang and colleagues (3) took advantage of the sharp reductions in pollutant levels achieved through intense restrictions on industrial operations and traffic in the Beijing area during the Olympics, followed by a rapid return to usual practices and more typical pre-Olympic pollutant concentrations after the Games. The use of quasiexperimental design in this panel study to estimate the effect of air pollution on the outcomes reduces the potential for confounding by long-term trends in health. Such confounding by trends in both the health outcomes of interest and air pollution levels over time has been a common challenge in air pollution health effects research. Furthermore, quasiexperimental studies of air pollution health effects are relatively unique, with a few notable exceptions. In the 1980s in Utah Valley, a labor dispute resulted in the intermittent operation of the local steel mill, the primary single source of air pollution in the valley, demonstrating significant associations between air pollution and hospital admissions for respiratory disease (12). A ban on coal sales in Dublin Ireland in 1990 resulted in an immediate and large reduction in particulate matter air pollution and corresponding significant reductions in respiratory and cardiovascular death rates (13). An initial analysis of the 1996 Atlanta Olympics took advantage of transiently reduced traffic levels and found some evidence of associations between changes in ozone and childhood asthma emergency room visits (14). However, compared with conditions in 2008 Beijing, the changes in air pollution were very small, and subsequent analyses were unable to disentangle the combined effects of meteorological conditions, reduced traffic, and intervention-related health effects (15). Related natural experiment studies also include studies of public smoking bans and evidence of related reductions in cardiovascular disease (16). Randomized experimental designs (including controlled exposure human studies) conceptually may be ideal for understanding the underlying mechanisms of air pollution–induced cardiac and pulmonary disease in humans, but obvious practical and ethical concerns significantly limit who can be exposed and the duration and intensity of exposure in such studies. Quasiexperimental designs with high pollution variability, such as the study in this issue of the Journal, allow important mechanistic inferences to be made about longer-term exposures under “real-world” conditions. Collectively, these recent Beijing Olympics studies lend support to the hypothesis that exposure to particulate matter induces inflammation and oxidative stress in the lungs and perhaps other tissues, which increases the tendency toward thrombosis and activates the sympathetic nervous system to increase the risk of cardiovascular death. These studies also suggest that even young and healthy individuals without pulmonary or cardiac disease may be susceptible to these effects of particulate matter, and provide additional promising novel biomarkers for investigating the mechanisms of air pollution–induced disease. Although this study measured multiple pollutants in an effort to understand how individual components of the complex air pollution mixture may impact disease, significant correlations between pollutants and the more general reduction of pollution that occurred during the Beijing Olympics limit the ability to make compelling inferences regarding the individual effects of specific pollutants on these markers. China and other rapidly industrializing nations face tremendous challenges over the next decades, with rapid development often competing with adverse environmental impacts, including increased levels of air pollution. Without serious efforts to control pollution, “business-as-usual” practices are likely lead to dramatic increases in concentrations not only in China, but worldwide. Although the emissions control policies that China has planned to implement may help to avert some of the public health impacts associated with air pollution exposures both locally and globally, many uncertainties remain (17). A recent global atmospheric chemistry model estimates that, without new legislation to prevent growth in air pollution, the average global citizen in 2050 will experience nearly the same air quality as the average East Asian citizen in 2005 (18). Although this model is hopefully a pessimistic scenario, it underscores the need for serious preventive action. This challenge of pollution control in the context of population and economic growth is not limited to developing nations like China. All nations bear the burden of controlling pollutants, which do not respect national borders. From countries with rapid expansion of industry to more established economies, and from Olympic athletes to “mere mortal” healthy young adults such as those evaluated in the study reported in this issue of the Journal, to individuals with preexisting health conditions—all face substantial challenges from air pollution now and in the future.