Changes In Ozone Concentrations Research Articles

Projecting Excess Mortality In 2030 With Spatially-Varying Ozone-Temperature Risk Surfaces

Background: Temperature and ozone have a nonlinear and synergistic effect on mortality. This relationship has not previously been incorporated into the health impact assessment of climate change on the ozone-related health burden. Objective: We estimate the change in ozone-related mortality between historical (1995-2005) and near-future (2025-2035) climates using a bivariate ozone-temperature health impact function. Methods: We use climate projections to simulate air quality with varying biogenic and constant anthropogenic emissions, which limits changes in ozone concentrations to changes in climate. We estimate nonlinear, spatially-varying, ozone-temperature risk surfaces in 94 US urban areas using observed data and evaluate daily mortality attributable to ozone based on climate projections for two scenarios: exceeding 40 ppb (moderate level) and 75 ppb (US O3 NAAQS). The climate penalty on mortality burden is the change in ozone-related excess mortality between time periods. Results: The average increases in city-specific median April-October ozone and temperature between time periods are 1.02ppb and 1.94°F, respectively. When considering climate mortality attributed to ozone exceeding 40ppb increases by 7.7% (1.6%, 14.2%), and mortality attributed to ozone exceeding 75ppb increases by 14.2% (1.6%, 28.9%). The absolute increase in excess mortality is larger for changes in moderate ozone levels, reflecting the larger number of days with moderate ozone levels. Conclusions: Climate change related increases in ozone result in an increase in ozone-mortality burden. Increases across moderate ozone levels account for a larger absolute increase in burden while increases at higher levels account for a larger relative increase, even after accounting for nonlinear and synergistic effects. Disclaimer: The contents of this article should not be construed to represent Agency policy.

Projection of PM2.5 and Ozone Concentration Changes over the Jing-Jin-Ji Region in China

AbstractBased on GISS-E2-R model simulations, the changes in PM2.5 and ozone concentrations during 2016–35 are analyzed over the Jing-Jin-Ji region under different future emissions scenarios: 2.6, 4.5, 6.0, 8.5 Representative Concentration Pathways scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5), compared to the baseline periods of 1851–70 (pre-industrial) and 1986–2005 (present day). The results show that PM2.5 increases under all emissions scenarios, with the maximum value occurring in the southeastern part of the region under most scenarios. As for ozone, its concentration is projected to increase during 2016–35 under all emissions scenarios, compared to the baseline periods. The temporal evolutions of PM2.5 and ozone show PM2.5 reaching a peak during 2020–40, while ozone will likely increase steadily in the future.

Detection of Changes in Ground-Level Ozone Concentrations via Entropy

Ground-level ozone concentration is a key indicator of air quality. Theremay exist sudden changes in ozone concentration data over a long time horizon, which may be caused by the implementation of government regulations and policies, such as establishing exhaust emission limits for on-road vehicles. To monitor and assess the efficacy of these policies, we propose a methodology for detecting changes in ground-level ozone concentrations, which consists of three major steps: data transformation, simultaneous autoregressive modelling and change-point detection on the estimated entropy. To show the effectiveness of the proposed methodology, the methodology is applied to detect changes in ground-level ozone concentration data collected in the Toronto region of Canada between June and September for the years from 1988 to 2009. The proposed methodology is also applicable to other climate data.

Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging

Abstract. Multi-model ensembles are frequently used to assess understanding of the response of ozone and methane lifetime to changes in emissions of ozone precursors such as NOx, VOCs (volatile organic compounds) and CO. When these ozone changes are used to calculate radiative forcing (RF) (and climate metrics such as the global warming potential (GWP) and global temperature-change potential (GTP)) there is a methodological choice, determined partly by the available computing resources, as to whether the mean ozone (and methane) concentration changes are input to the radiation code, or whether each model's ozone and methane changes are used as input, with the average RF computed from the individual model RFs. We use data from the Task Force on Hemispheric Transport of Air Pollution source–receptor global chemical transport model ensemble to assess the impact of this choice for emission changes in four regions (East Asia, Europe, North America and South Asia). We conclude that using the multi-model mean ozone and methane responses is accurate for calculating the mean RF, with differences up to 0.6% for CO, 0.7% for VOCs and 2% for NOx. Differences of up to 60% for NOx 7% for VOCs and 3% for CO are introduced into the 20 year GWP. The differences for the 20 year GTP are smaller than for the GWP for NOx, and similar for the other species. However, estimates of the standard deviation calculated from the ensemble-mean input fields (where the standard deviation at each point on the model grid is added to or subtracted from the mean field) are almost always substantially larger in RF, GWP and GTP metrics than the true standard deviation, and can be larger than the model range for short-lived ozone RF, and for the 20 and 100 year GWP and 100 year GTP. The order of averaging has most impact on the metrics for NOx, as the net values for these quantities is the residual of the sum of terms of opposing signs. For example, the standard deviation for the 20 year GWP is 2–3 times larger using the ensemble-mean fields than using the individual models to calculate the RF. The source of this effect is largely due to the construction of the input ozone fields, which overestimate the true ensemble spread. Hence, while the average of multi-model fields are normally appropriate for calculating mean RF, GWP and GTP, they are not a reliable method for calculating the uncertainty in these fields, and in general overestimate the uncertainty.

수도권 미래 도시성장이 오존농도 변화에 미치는 영향 연구

【In this study, the regional climate (WRF) and air quality (CMAQ) models were used to simulate the effects of future urban growth on surface ozone concentrations in the Seoul metropolitan region (SMR). These analyses were performed based on changes in ozone concentrations during ozone seasons (May-June) for the year 2050 (future) relative to 2012 (present) by urban growth. The results were compared with the impacts of RCP scenarios on ozone concentrations in the SMR. The fractions of urban in the SMR (25.8 %) for the 2050 were much higher than those (13.9 %) for the 2012 and the future emissions (e.g., CO, NO, $NO_2$ , $SO_2$ , VOC) were increased from 121 % (NO) to 161.3 % ( $NO_2$ ) depending on emission material. The mean and daily maximum 1-h ozone in the SMR increased about 3 - 7 ppb by the effect the RCP scenarios. However, the effect of urban growth reduced the mean ozone by 3 ppb in the SMR and increased the daily maximum 1-h ozone by 2 - 5 ppb over the northeastern SMR and around the coastline. In particular, the ozone pollution days exceeding the 1-h regulatory standard (100 ppb) were far more affected by urban growth than mean values. As a result, the average number of days exceeding the 1-h regulatory standard increased up to 10 times.】

Projection of PM2.5and Ozone Concentration Changes over the Jing-Jin-Ji Region in China

Projection of PM_2.5and Ozone Concentration Changes over the Jing-Jin-Ji Region in China

Relationships between Ambient Ozone Concentration Changes in Southwestern Taiwan and Invasion Tracks of Tropical Typhoons

This study aimed to use a newly developed weather and air quality model, WRF-Chem, to simulate and analyze formation of high-concentrated ozone (O3) in the ambient air of southwestern Taiwan before the invasion of tropical typhoons. Two typical typhoons, Nanmadol and Usagi that occurred in 2011 and 2013, respectively, were simulated in this study. The O3concentration variation patterns in the ambient air of both offshore and inland parts of southwestern Taiwan were collected and analyzed. The results indicated that the high O3concentration observed in southwestern Taiwan before typhoon arrived was mainly caused by the western Pacific subtropical high (WPSH) shrouding it. On the other hand, the latter increase in ambient O3concentration about 1 to 2 days before issuing sea warning was mainly due to both contributions of weakening WPSH and intensifying leeward side effects. For both cases, atmospheric subsidence occurred to result in low ambient air quality. The invasion of typhoons made ambient O3concentration enhanced up to 2-3-fold compared to its normal concentration in summer. Based on the simulated O3concentration variation results in this study, it is demonstrated that the space-fading patterns of O3before typhoon arrives also can be used as references for predicting typhoon moving tracks 1.0 to 2.0 days before landfall of typhoons.

An evaluation of ozone dry deposition simulations in East Asia

Abstract. We use a 3-D regional atmospheric chemistry transport model (WRF-Chem) to examine ozone dry deposition in East Asia, which is an important but uncertain research area because of insufficient observation and numerical studies focusing on East Asia. Here we compare two widely used dry deposition parameterization schemes, the Wesely and M3DRY schemes, which are used in the WRF-Chem and Community Multiscale Air Quality (CMAQ) models, respectively. Simulated ozone dry deposition velocities with the two schemes under identical meteorological conditions show considerable differences (a factor of 2) owing to surface resistance parameterization discrepancies. Resulting ozone concentrations differ by up to 10 ppbv for a monthly mean in May when the peak ozone typically occurs in East Asia. An evaluation of the simulated dry deposition velocities shows that the Wesely scheme calculates values with more pronounced diurnal variation than the M3DRY and results in a good agreement with the observations. However, we find significant changes in simulated ozone concentrations using the Wesely scheme but with different surface type data sets, indicating the high sensitivity of ozone deposition calculations to the input data. The need is high for observations to constrain the dry deposition parameterization and its input data to improve the use of air quality models for East Asia.

The impacts of two types of El Niño on global ozone variations in the last three decades

The effects of El Nino Modoki events on global ozone concentrations are investigated from 1980 to 2010 El Nino Modoki events cause a stronger Brewer-Dobson (BD) circulation which can transports more ozone-poor air from the troposphere to stratosphere, leading to a decrease of ozone in the lower-middle stratosphere from 90°S to 90°N. These changes in ozone concentrations reduce stratospheric column ozone. The reduction in stratospheric column ozone during El Nino Modoki events is more pronounced over the tropical eastern Pacific than over other tropical areas because transport of ozone-poor air from middle-high latitudes in both hemispheres to low latitudes is the strongest between 60°W and 120°W. Because of the decrease in stratospheric column ozone during El Nino Modoki events more UV radiation reaches the tropical troposphere leading to significant increases in tropospheric column ozone An empirical orthogonal function (EOF) analysis of the time series from 1980 to 2010 of stratospheric and tropospheric ozone monthly anomalies reveals that: El Nino Modoki events are associated with the primary EOF modes of both time series. We also found that El Nino Modoki events can affect global ozone more significantly than canonical El Nino events. These results imply that El Nino Modoki is a key contributor to variations in global ozone from 1980 to 2010.

Long‐term changes in lower tropospheric baseline ozone concentrations: Comparing chemistry‐climate models and observations at northern midlatitudes

AbstractTwo recent papers have quantified long‐term ozone (O3) changes observed at northern midlatitude sites that are believed to represent baseline (here understood as representative of continental to hemispheric scales) conditions. Three chemistry‐climate models (NCAR CAM‐chem, GFDL‐CM3, and GISS‐E2‐R) have calculated retrospective tropospheric O3 concentrations as part of the Atmospheric Chemistry and Climate Model Intercomparison Project and Coupled Model Intercomparison Project Phase 5 model intercomparisons. We present an approach for quantitative comparisons of model results with measurements for seasonally averaged O3 concentrations. There is considerable qualitative agreement between the measurements and the models, but there are also substantial and consistent quantitative disagreements. Most notably, models (1) overestimate absolute O3 mixing ratios, on average by ~5 to 17 ppbv in the year 2000, (2) capture only ~50% of O3 changes observed over the past five to six decades, and little of observed seasonal differences, and (3) capture ~25 to 45% of the rate of change of the long‐term changes. These disagreements are significant enough to indicate that only limited confidence can be placed on estimates of present‐day radiative forcing of tropospheric O3 derived from modeled historic concentration changes and on predicted future O3 concentrations. Evidently our understanding of tropospheric O3, or the incorporation of chemistry and transport processes into current chemical climate models, is incomplete. Modeled O3 trends approximately parallel estimated trends in anthropogenic emissions of NOx, an important O3 precursor, while measured O3 changes increase more rapidly than these emission estimates.

Air quality resolution for health impact assessment: influence of regional characteristics

Abstract. We evaluate how regional characteristics of population and background pollution might impact the selection of optimal air quality model resolution when calculating the human health impacts of changes to air quality. Using an approach consistent with air quality policy evaluation, we use a regional chemical transport model (CAMx) and a health benefit mapping program (BenMAP) to calculate the human health impacts associated with changes in ozone and fine particulate matter resulting from an emission reduction scenario. We evaluate this same scenario at 36, 12 and 4 km resolution for nine regions in the eastern US representing varied characteristics. We find that the human health benefits associated with changes in ozone concentrations are sensitive to resolution. This finding is especially strong in urban areas where we estimate that benefits calculated using coarse resolution results are on average two times greater than benefits calculated using finer scale results. In three urban areas we analyzed, results calculated using 36 km resolution modeling fell outside the uncertainty range of results calculated using finer scale modeling. In rural areas the influence of resolution is less pronounced with only an 8% increase in the estimated health impacts when using 36 km resolution over finer scales. In contrast, health benefits associated with changes in PM2.5 concentrations were not sensitive to resolution and did not follow a pattern based on any regional characteristics evaluated. The largest difference between the health impacts estimated using 36 km modeling results and either 12 or 4 km results was at most ±10% in any region. Several regions showed increases in estimated benefits as resolution increased (opposite the impact seen with ozone modeling), while some regions showed decreases in estimated benefits as resolution increased. In both cases, the dominant contribution was from secondary PM. Additionally, we found that the health impacts calculated using several individual concentration–response functions varied by a larger amount than the impacts calculated using results modeled at different resolutions. Given that changes in PM2.5 dominate the human health impacts, and given the uncertainty associated with human health response to changes in air pollution, we conclude that, when estimating the human health benefits associated with decreases in ozone and PM2.5 together, the benefits calculated at 36 km resolution agree, within errors, with the benefits calculated using fine (12 km or finer) resolution modeling when using the current methodology for assessing policy decisions.

Climate Change Impacts on Plant Pathogens and Plant Diseases

The effects of climate change on plant pathogens and the diseases they cause have been examined in some pathosystems. Predicted climatic changes are expected to affect pathogen development and survival rates and modify host susceptibility, resulting in changes in the impact of diseases on crops. The effects of these climatic changes will differ by pathosystem and geographical region. These changes may affect not only the optimal conditions for infection but also host specificity and mechanisms of plant infection. We describe research on the effects of changes in temperature, CO2 and ozone concentrations, precipitation, and drought on the biology of pathogens and their ability to infect plants and survive in natural and agricultural environments. Changing abiotic conditions will also affect the microclimate surrounding plants and the susceptibility of plants to infection. These changing conditions are expected to affect microbial communities in the soil and canopy pathosystems, possibly altering the currently observed beneficial effects of these communities. Because both pathogens and host plants will be affected by the changing climate, dramatic changes in the magnitude of disease expression in a given pathosystem, the geographical distribution of particular plant diseases, the economic importance of particular diseases in a given location, and the set of diseases that challenge each crop are expected. These changes will affect the measures farmers use to effectively manage disease, as well as the feasibility of particular cropping systems in particular regions.

The Impact of Climate Change on Ozone-Related Mortality in Sydney

Coupled global, regional and chemical transport models are now being used with relative-risk functions to determine the impact of climate change on human health. Studies have been carried out for global and regional scales, and in our paper we examine the impact of climate change on ozone-related mortality at the local scale across an urban metropolis (Sydney, Australia). Using three coupled models, with a grid spacing of 3 km for the chemical transport model (CTM), and a mortality relative risk function of 1.0006 per 1 ppb increase in daily maximum 1-hour ozone concentration, we evaluated the change in ozone concentrations and mortality between decades 1996–2005 and 2051–2060. The global model was run with the A2 emissions scenario. As there is currently uncertainty regarding a threshold concentration below which ozone does not impact on mortality, we calculated mortality estimates for the three daily maximum 1-hr ozone concentration thresholds of 0, 25 and 40 ppb. The mortality increase for 2051–2060 ranges from 2.3% for a 0 ppb threshold to 27.3% for a 40 ppb threshold, although the numerical increases differ little. Our modeling approach is able to identify the variation in ozone-related mortality changes at a suburban scale, estimating that climate change could lead to an additional 55 to 65 deaths across Sydney in the decade 2051–2060. Interestingly, the largest increases do not correspond spatially to the largest ozone increases or the densest population centres. The distribution pattern of changes does not seem to vary with threshold value, while the magnitude only varies slightly.

高浓度O3及太阳辐射减弱对冬小麦PSⅡ光合活性及光能耗散的影响

为给地表太阳辐射减弱和O₃浓度增加等大气环境变化条件下我国粮食生产和安全提供安全评估依据，利用开顶式气室（OTC）和黑色遮光网开展了1种熏气水平和2种辐射减弱程度的大田试验（野外CK，T1：遮光20%，T2：遮光40%，T3：O₃浓度100 nL/L，T4：O₃浓度100 nL/L与遮光20%复合，T5：O₃浓度100 nL/L与遮光40%复合）。结果表明：T1、T2和T4组的<em>Fv/Fm</em>、<em>L</em>_（PFD）与CK均相似且变化不明显，Yield、<em>qP</em>、<em>Y</em>（<em>NO</em>）、（1-<em>qP</em>）/<em>NPQ</em>分别较CK不同程度下降，而<em>NPQ</em>和<em>Y</em>（<em>NPQ</em>）较CK分别较大程度升高；T3-T5组的<em>Fv/Fm</em>，<em>L</em>_（PFD） 、Yield、<em>qP</em>、<em>Y</em>（<em>NO</em>）和（1-<em>qP</em>）/<em>NPQ</em>较CK不同程度降低，而<em>NPQ</em>和<em>Y</em>（<em>NPQ</em>）较CK分别显著升高且T5增幅显著大于T1-T4组。综上表明，复合胁迫下，冬小麦光能更多地向调节性热耗散途径分配，辐射减弱效应能使臭氧胁迫下冬小麦较好地自我调节以更好地适应逆境环境。尽管冬小麦对复合胁迫具有一定的适应能力，地表臭氧浓度升高和辐射减弱仍然是我国粮食生产中面临的一个重要问题。;At present, the aerosol radiative effect is the focus of many scholars and the solar radiation attenuated by direct or indirect effect to cause crop photosynthetic capacity decreased, resulting in crop production; At the same time the surface concentration of O₃ continuously increased, O₃ has strong negative effect on crop growth and metabolic processes and O₃ was direct threat to food safety to crops. Providing the basis for the security of National grain assessments and production under the conditions of reduced solar irradiance and elevated ozone concentration and other changes in atmospheric. Used open-top chamber (OTC) and black shading network to launch a fumigation level and two kinds of irradiance reduction degree. (field: CK, T1: shading 20%, T2: shading 40%, T3: 100nL/L O₃ concentration, T4: 100nL/L O₃ concentration and shading 20% compound, T5: 100nL/L O₃ concentration and shading 40% compound). The results showed that contrasting to CK, the <em>Fv/Fm</em>(PSⅡ maximum quantum yield), <em>L</em>_(PFD) (the relative limit of Photosynthetic function) of T1 treatment are similar and had no obvious changes, but the Yield, <em>qP</em>(Photochemical quenching coefficient), <em>Y(NO)</em> (the non regulation of energy dissipation in quantum yield), (1-<em>qP</em>)/<em>NPQ</em>(Light quantum excess degree) are decreased by 1.3%-21.5%, 7.5%-21.2%, 14.8%-20.6%, 27.7%-51.4% and NPQ(non photochemical quenching coefficient), <em>Y (NPQ)</em>(regulation of energy dissipation in quantum yield) are increased by 12.0%-31.9%, 53.4%-116%. Fv/Fm of T2 treatment had no significant changes, The Yield, <em>qP</em>, <em>L</em>_(PFD), <em>Y(NO)</em>, (1-<em>qP</em>)/<em>NPQ</em> were decreased by 13.2%-34.0%, 16.9%-36.2%, 6.8%-8.3%, 2.8%-16.0%, 23.1%-32.7%, The <em>NPQ</em>, <em>Y(NPQ)</em> were increased downby 15.9%-38.2% 39.5%-65.4%. The <em>Fv/Fm</em>, Yield(Optical system II actual photochemical efficiency), <em>qP</em> of T3 treatment were decreased by 11.8%-12.6%, 19.1%-28.0%, 15.6%-43.1%. The <em>L</em>_(PFD), <em>NPQ</em>, <em>Y</em>(<em>NPQ</em>), <em>Y</em>(<em>NO</em>), (1-<em>qP</em>)/<em>NPQ</em> increased by 1.1%-7.2%, 20.8%-83.6%, 12.6%-40.3%, 3.9%-22.2% obviously, 0.6%-34.1%. <em>Fv/Fm</em>, <em>L</em>_(PFD) of T4 treatment were similar to CK and compared with CK, the Yield, <em>qP</em>, <em>Y(NO)</em>, (1-<em>qP</em>)/<em>NPQ</em> decreased by 12.7%-42.8%, 7.2%-14.4% 18.8%-27.5%, 16.4%-45.1% and <em>NPQ, Y(NPQ)</em> increased by 13.4%-45.2% 6.9%-110.8%. <em>Fv/Fm</em>, Yield, <em>qP</em>, <em>L</em>_(PFD), </em>Y(NO)</em>, (1-<em>qP</em>)/<em>NPQ</em> of T5 treatment compared with CK, decreased by 30.4%-50.9%, 27.7%-43.2%, 2.2%-4.9%, 2.2%-10.2%, 23.3%-26.2%, 47.1%-61.6% and <em>NPQ</em>, <em>Y(NPQ)</em> increased by 27.5%-51.6% 63.3%-142.7%. Those results showed that (1) the single factor of Ozone significantly changed photosynthetic activity and distribution of light energy of winter wheat leaves but the single factor of reduced solar radiation alleviated negative effect photosynthesis restriction of winter wheat to a certain extent. (2) Further, under the combined stress, the light energy of winter wheat distributed more to regulatory heat dissipation. Composite action enhanced obviously the heat dissipation capability of winter wheat Radiation attenuation effect could cause winter wheat at the ozone stress self-regulated to better adapt to the adverse environment. Reducing appropriate the amount of solar radiation under Ozone stress could alleviate and reduce the light injury of winter wheat leaves. (3) Reducing solar radiation under the Ozone stress could inhibition the light injury and ensure the winter wheat optical system function normally and the normal growth of Winter Wheat. (4) In spite of winter wheat on composite stress has a certain ability to adapt; the reduced solar irradiance and elevated ozone concentration are still an important issue facing national grain production.

Circulation anomalies in the Southern Hemisphere and ozone changes

Abstract. We report results from two pairs of chemistry-climate model simulations using the same climate model but different chemical perturbations. In each pair of experiments an ozone change was triggered by a simple change in the chemistry. One pair of model experiments looked at the impact of polar stratospheric clouds (PSCs) and the other pair at the impact of short-lived halogenated species on composition and circulation. The model response is complex with both positive and negative changes in ozone concentration, depending on location. These changes result from coupling between composition, temperature and circulation. Even though the causes of the modelled ozone changes are different, the high latitude Southern Hemisphere response in the lower stratosphere is similar. In both pairs of experiments the high-latitude circulation changes, as evidenced by N2O differences, are suggesting a slightly longer-lasting/stronger stratospheric descent in runs with higher ozone destruction (a manifestation of a seasonal shift in the circulation). We contrast the idealised model behaviour with interannual variability in ozone and N2O as observed by the MIPAS instrument on ENVISAT, highlighting similarities of the modelled climate equilibrium changes to the year 2006–2007 in observations. We conclude that the climate system can respond quite sensitively in its seasonal evolution to small chemical perturbations, that circulation adjustments seen in the model can occur in reality, and that coupled chemistry-climate models allow a better assessment of future ozone and climate change than recent CMIP-type models with prescribed ozone fields.

Climate Change Impacts of Ozone on Morbidity in Vulnerable Populations across the Life Stages in 2050, Mecklenburg County, North Carolina, USA

Background: Climate- and emissions-related changes in ozone concentrations will likely impact both morbidity and mortality; these changes may have greater effects on vulnerable populations such as children and older adults. Aims: 1) Estimate the climate- and emissions-related impacts on ozone-related cardiopulmonary morbidity burden from 2006-2011 to 2048-2050 in Mecklenburg County, North Carolina (NC), an urban county in Southeastern United States with over 900,000 residents. 2) Assess the sensitivity of results to alternate population growth and age structure scenarios. Methods: We obtained respiratory and cardiovascular emergency department (ED) visit data from Mecklenburg County for April-October 2006-2011 from the NC Disease Event Tracking and Epidemiologic Collection Tool surveillance system. We estimate baseline ozone-morbidity associations with a time-series model of merged daily ozone monitor data and ED visit counts. We generate projected ozone concentration grids (12km) for 2048-2050 with the Community Multi-scale Air Quality (CMAQ) chemistry transport model using the IPCC A1B emissions scenario and assuming emission changes from anthropogenic sources only . We use a health impact assessment framework to estimate the projected changes in ED visits and the influence of alternate demographic scenarios in 2050. Results: 39,515 eligible ED visits (19,812 cardiovascular, 19,703 respiratory) occurred during the 2006-2011 baseline study period, with mean daily count of 31.5 (SD 7.6). Daily maximum 8-hour average ozone concentrations ranged from 3 to 127 ppb, with median of 51 ppb; May-August 2050 ozone projections indicate decreasing ozone levels, with a median of 36 ppb and range of 18-62 ppb. Baseline associations, projected health impacts, and sensitivity to alternate demographic scenarios will be presented. Conclusions: Climate change, air quality regulation, and population dynamics will likely alter future demand for ED services. These projections can be used to inform local public health preparedness and support continued air pollution mitigation.

Major Factors Influencing the Health Impacts from Controlling Air Pollutants with Nonlinear Chemistry: An Application to China

Predicting the human-health effects of reducing atmospheric emissions of nitrogen oxide (NOx) emissions from power plants, motor vehicles, and other sources is complex because of nonlinearity in the relevant atmospheric processes. We estimate the health impacts of changes in fine particulate matter (PM2.5) and ozone concentrations that result from control of NOx emissions alone and in conjunction with other pollutants in and outside the mega-city of Shanghai, China. The Community Multiscale Air Quality (CMAQ) Modeling System is applied to model the effects on atmospheric concentrations of emissions from different economic sectors and geographic locations. Health impacts are quantified by combining concentration-response functions from the epidemiological literature with pollutant concentration and population distributions. We find that the health benefits per ton of emission reduction are more sensitive to the location (i.e., inside vs. outside of Shanghai) than to the sectors that are controlled. For eastern China, we predict between 1 and 20 fewer premature deaths per year per 1,000 tons of NOx emission reductions, valued at $300-$6,000 per ton. Health benefits are sensitive to seasonal variation in emission controls. Policies to control NOx emissions need to consider emission location, season, and simultaneous control of other pollutants to avoid unintended consequences.

Characterization and reactivity of cerium loaded MCM-41 for p-chlorobenzoic acid mineralization with ozone

Mesoporous molecular sieve MCM-41 and Cerium-loaded MCM-41 (Ce/MCM-41) were synthesized and used as heterogeneous catalysts for ozonation of p-chlorobenzoic acid (p-CBA) in aqueous solution. MCM-41 and Ce/MCM-41 were characterized by XRD, TEM, SEM, ICP-AES and N2 adsorption–desorption techniques. The results showed that Ce/MCM-41 retained a highly ordered mesoporous structure and had a surface area of 953m2g−1. The presence of Ce/MCM-41 obviously improved the mineralization of p-CBA and the conversion rate of organic chlorine. The conversion rate of organic chlorine in Ce/MCM-41/O3 process was 94% along with the degradation of p-CBA in the first 10min (73.3% by O3 alone and 78.6% by MCM-41/O3), TOC removal efficiency by Ce/MCM-41/O3 process was 94% at 60min (63% by MCM-41/O3 and only 52% by O3 alone), and the leaching of cerium was only 0.097mgl−1. The combination of Ce/MCM-41 and O3 exhibited a significant synergetic effect. Both pH changes of aqueous solution and the presence of hydroxyl radical scavenger tert-butanol (TBA) proved that Ce/MCM-41 catalytic ozonation of p-CBA followed the HO oxidation mechanism. The changes of ozone concentration indicated that the presence of Ce/MCM-41 could promote ozone decomposition into hydroxyl radical, and improve the utilization rate of ozone. Lewis acid sites and the hydroxyl group existing on the surface of catalyst were believed to be the initiator of ozone decomposition to generate HO.

Air pollution and early deaths in the United States. Part I: Quantifying the impact of major sectors in 2005

Combustion emissions adversely impact air quality and human health. A multiscale air quality model is applied to assess the health impacts of major emissions sectors in United States. Emissions are classified according to six different sources: electric power generation, industry, commercial and residential sources, road transportation, marine transportation and rail transportation. Epidemiological evidence is used to relate long-term population exposure to sector-induced changes in the concentrations of PM2.5 and ozone to incidences of premature death. Total combustion emissions in the U.S. account for about 200,000 (90% CI: 90,000–362,000) premature deaths per year in the U.S. due to changes in PM2.5 concentrations, and about 10,000 (90% CI: −1000 to 21,000) deaths due to changes in ozone concentrations. The largest contributors for both pollutant-related mortalities are road transportation, causing ∼53,000 (90% CI: 24,000–95,000) PM2.5-related deaths and ∼5000 (90% CI: −900 to 11,000) ozone-related early deaths per year, and power generation, causing ∼52,000 (90% CI: 23,000–94,000) PM2.5-related and ∼2000 (90% CI: −300 to 4000) ozone-related premature mortalities per year. Industrial emissions contribute to ∼41,000 (90% CI: 18,000–74,000) early deaths from PM2.5 and ∼2000 (90% CI: 0–4000) early deaths from ozone. The results are indicative of the extent to which policy measures could be undertaken in order to mitigate the impact of specific emissions from different sectors — in particular black carbon emissions from road transportation and sulfur dioxide emissions from power generation.

Comparison of three vertically resolved ozone data sets: climatology, trends and radiative forcings

Abstract. Climate models that do not simulate changes in stratospheric ozone concentrations require the prescription of ozone fields to accurately calculate UV fluxes and stratospheric heating rates. In this study, three different global ozone time series that are available for this purpose are compared: the data set of Randel and Wu (2007) (RW07), Cionni et al. (2011) (SPARC), and Bodeker et al. (2013) (BDBP). All three data sets represent multiple-linear regression fits to vertically resolved ozone observations, resulting in a spatially and temporally continuous stratospheric ozone field covering at least the period from 1979 to 2005. The main differences among the data sets result from regression models, which use different observations and include different basis functions. The data sets are compared against ozonesonde and satellite observations to assess how the data sets represent concentrations, trends and interannual variability. In the Southern Hemisphere polar region, RW07 and SPARC underestimate the ozone depletion in spring ozonesonde measurements. A piecewise linear trend regression is performed to estimate the 1979–1996 ozone decrease globally, covering a period of extreme depletion in most regions. BDBP overestimates Arctic and tropical ozone depletion over this period relative to the available measurements, whereas the depletion is underestimated in RW07 and SPARC. While the three data sets yield ozone concentrations that are within a range of different observations, there is a large spread in their respective ozone trends. One consequence of this is differences of almost a factor of four in the calculated stratospheric ozone radiative forcing between the data sets (RW07: −0.038 Wm−2, SPARC: −0.033 Wm−2, BDBP: −0.119 Wm−2), important in assessing the contribution of stratospheric ozone depletion to the total anthropogenic radiative forcing.