Increase In Ozone Levels Research Articles

The By-Product of Ozone from Electrostatic Air Cleaners

Indoor Air Quality (IAQ) contributes to the health and comfort of people living and working indoors. Poor IAQ can be linked to indoor and outdoor sources of contaminants. One recent solution for improving IAQ is the use of Electrostatic (ES) Air Cleaning technology. An ES air cleaner can be installed in an heating, ventilation, and air conditioning system where it pre-filters large dust particles and shocks smaller particles into a collection tray. However, ES air cleaners have been known to give off ozone as a by-product, which is, itself, an air contaminant. Ozone is found outdoors as product of sunlight combining nitrogen oxides and volatile organic compounds generated from man-made pollution. Indoor ozone concentration will depend on the introduction of outdoor ozone indoors through natural ventilation, mechanical ventilation, and infiltration through the building’s envelope (in order of importance). Two different ES air cleaners, A and B, were installed in the air conditioning system of research House #2 of the TRANE Residential Heating and Cooling Research Lab at the University of Texas at Tyler. A series of ozone experiments were conducted, which included measuring the baseline ozone levels at the research houses with different levels of insulation, observing the increase in ozone due to the powering on of mechanical ventilation, and observing the increase in ozone due to the powering on of the installed ES air cleaners. The baseline ozone levels observed in research house #2, whose envelope is more tightly insulated, was found to be lower than in research house #1 whose envelope is less tightly insulated. With regards to mechanical ventilation, an increase in ozone levels were seen in addition to an even higher increase in ozone levels when the ES air cleaners were powered on in tandem. In terms of the single contribution of the ES air cleaners in raising indoor ozone levels, the data shows that although the ES air cleaners increased the ozone concentration in the house, the levels are not of concern as they were less than the FDA limit on indoor ozone generation. KEYWORDS: Indoor Air Quality; Ozone; Electrostatic Air Cleaner; Infiltration; Mechanical Ventilation; HVAC; Pollutant; Indoor Contaminant

The Impact of Sporting Events on Air Pollution: An Empirical Examination of National Football League Games

(1) Background: Prior research has found that large-scale sporting events may potentially impose negative consequences on the environment, thus impeding the sustainability goals of the sport industry. Along these lines, the current study extends the literature by examining the impact that National Football League (NFL) games have on local-area air pollution. (2) Methods: Air Quality Index (AQI) data measuring six major forms of air pollution were gathered from air monitors positioned close to NFL stadiums and matched with the number of attendees at games. From this, multiple regression analysis was utilized to estimate whether the number of fans was related to changes in air pollution. (3) Results: The regression models found that Ozone and Nitrogen Dioxide levels increased as more individuals attended NFL games. Additional robustness checks and falsification tests suggest that the average NFL event results in an approximately two-percent increase in Ozone levels. (4) Conclusions: The findings from this study contribute to the literature by providing evidence that highly attended sporting events increase pollution levels in the areas near stadiums. Thus, governments and sport organizations should consider low-emission methods to get fans to travel to games in order to reduce their environmental impact.

Local and regional air pollution characteristics in Cyprus: A long-term trace gases observations analysis

Observations of key gaseous trace pollutants, namely NO, NOy, CO, SO2 and O3, performed at several curb, residential, industrial, background and free-troposphere sites were analyzed to assess the temporal and spatial variability of pollution in Cyprus. Notably, the analysis utilized one of the longest datasets of 17 years of measurements (2003–2019) in the East Mediterranean and the Middle East (EMME). This region is considered a regional hotspot of ozone and aerosol pollution.A trend analysis revealed that at several stations, a statistically significant decrease in primary pollutant concentration is recorded, most likely due to pollution control strategies. In contrast, at four stations, a statistically significant increase in ozone levels, ranging between 0.36 ppbv y−1 and 0.82 ppbv y−1, has been observed, attributed to the above strategies targeting the reduction of nitrogen oxides (NOx) but not that of Volatile Organic Compounds (VOCs).The NO and NOy, and CO levels at the Agia Marina regional background station were two orders of magnitude and four times lower, respectively, than the ones of the urban centers. The latter denotes that local emissions are not negligible and control a large fraction of the observed interannual and diurnal variability. Speciation analysis showed that traffic and other local emissions are the sources of urban NO and NOy. At the same time, 46 % of SO2 and 40 % of CO, on average, originate from long-range regional transport.Lastly, a one-year analysis of tropospheric NO2 vertical columns from the TROPOMI satellite instrument revealed a west-east low-to-high gradient over the island, with all major hotspots, including cities and powerplants, being visible from space. With the help of an unsupervised machine learning approach, it was found that these specific hotspots contribute overall around 10 % to the total NO2 tropospheric columns.

Evaluation of the impact of the COVID-19 pandemic on photochemical pollution in urban areas

Background: The effect of confinement due to the coronavirus disease 2019 (COVID-19) pandemic on air pollution has been investigated in several cities. Indeed, the concentration of the main air pollutants have decreased significantly due to the decline in activities consuming fossil fuels. However, it was found that the concentration of ozone (O3) has increased in Nice, Rome, Valence, Barcelona, Turin, and Wuhan. The main objective of this study was to assess the impact of the COVID-19 pandemic on photochemical pollution in Oran, Algeria. Methods: In Oran, a port city in the north-west of Algeria, the level of tropospheric ozone pollution was measured automatically every 15 min for 10 days at the same location before and after the confinement period, using an electronic nose, called APOMOS (air pollution monitoring system). This electronic circuit is equipped with an electrochemical sensor (MQ131) as well as a temperature and humidity sensor. Sampling was carried out in the central part of the Oran agglomeration from May to June 2020. The data related to the direction and intensity of the wind were processed to find a correlation between these parameters and the concentration of ozone in the studied area. Results: The impact of confinement on the increase of the ozone pollution levels in Oran, was estimated to be 52%. On the other hand, the statistical study of the pollution levels, the intensity and direction of the wind indicates that the important part of the downtown is involved in the generation of tropospheric ozone. Conclusion: The confinement due to the COVID-19 pandemic in Oran led to the reduction of the road traffic and pollutants emissions and the increase of ozone levels in urban area. Thus, ozone was less degraded because there were low levels of nitrogen oxides (NOx) in the atmosphere of this city during the confinement period.

Interactions Between Air Pollution and Pollen Season for Rhinitis Using Mobile Technology: A MASK-POLLAR Study

Several studies have suggested an interaction between air pollution and pollen exposure with an impact on allergy symptoms. However, large studies with real-life data are not available. To investigate associations between major air pollutants (ozone and particulate matter with a diameter of <2.5 μm) and allergic rhinitis (AR) control during grass and birch pollen seasons as well as outside the pollen season. The daily impact of allergic symptoms was recorded by the Allergy Diary (Mobile Airways Sentinel NetworK [MASK-air]) app (a validated mHealth tool for rhinitis management) using visual analog scales (VASs) in Northern and Central Europe users in 2017 and 2018. Uncontrolled AR was defined using symptoms and medications. Pollutant levels were assessed using the System for Integrated modeLing of Atmospheric coMposition database. Pollen seasons were assessed by regions using Google Trends. Generalized estimating equation models were used to account for repeated measures per user, adjusting for sex, age, treatment, and country. Analyses were stratified by pollen seasons to investigate interactions between air pollutants and pollen exposure. A total of 3323 geolocated individuals (36,440 VAS-days) were studied. Associations between uncontrolled rhinitis and pollutants were stronger during the grass pollen season. Days with uncontrolled AR increased by 25% for an interquartile range increase in ozone levels during the grass pollen season (odds ratio of 1.25 [95% CI, 1.11-1.41] in 2017 and of 1.14 [95% CI, 1.04-1.25] in 2018). A similar trend was found for particulate matter with a diameter of less than 2.5 μm, especially in2017. These results suggest that the relationship between uncontrolled AR and air pollution is modified by the presence of grass pollens. This study confirms the impact of pollutants in the grass pollen season but not in the birch pollen season.

Mitigation of climate change from the aspect of controlling F-gases in the field of cooling technology

The main objective is to identify, analyze and deliver data on F-gases in Bosnia and Herzegovina and identify potential mitigation measures. Bosnia and Herzegovina became a member of the United Nations Framework Convention on Climate Change (UNFCCC) on December 6, 2000. In its status as non-Annex I country within the UNFCCC, Bosnia and Herzegovina is obliged to undertake the following reporting activities, such as: to calculate annual emissions of greenhouse gases using a defined methodology and reporting to the Conference of the Parties (COP), introduce and implement measures to mitigate the effects of climate change by regulating anthropogenic emissions and adaptation measures to climate change. Also cooperates in the development and transfer of technology, methods and processes that lead to limitation, reduction and stabilization of greenhouse gas emissions, include an impact assessment of climate change and appropriate economic development strategies and policies aimed at minimizing the negative impacts of climate change on the economy, the environment and the health of the population; conduct systematic observation and research, exchange data and exchange information on climate and climate change in order to improve scientific discoveries on the causes and consequences of climate change.This project not only supports the country of Bosnia and Herzegovina in fulfilling the above obligations as a signatory to the UNFCCC, but will also serve as an important strategic document for sustainable development. Also, this project promotes relations between entities and business sectors, establishing links between the environment and other sectors. The data on the emission of F-gases in Bosnia and Herzegovina, including sources of these gases, are provided. In this paper, potentially intrusive measures are suggested. Ozone is a gas located in the earth’s atmosphere in a layer of 15 to 35 km above the Earth and has a special significance for the planets and the entire life on it. It is very important his role for the protection of life on Earth, and the disrupted occurrences of ozone flows through the atmosphere can have harmful effects on the health of man and the environment as a whole. The amount of ozone in the tropospheric (in the first lower layer above the Earth) and the tratospheric (upper-upper layer) was in the past in a natural balance. Uncontrolled human activity, in particular the development of the refrigeration industry, and the accelerated increase in the emissions of individual industrial gases, there was an increase in ozone levels in the tropospheric layer and in the stratospheric reduction. Concentration of ozone in the stratosphere and troposphere is limited by the balance between the chemical processes produced by ozone and the processes that destroy it. This equilibrium of the process is determined and depends on the amount of gases (involved in the reaction) and the speed (or efficiency of individual reactions), depending on the intensity of sunlight, location and area in the atmosphere, temperature and other natural climate factors. Global ozone has declined steadily over the last few decades. The Earth’s stratosphere has increased the amount of reactive gases, containing chlorine and bromine. The biggest impact on climate change is the carbon dioxide emission CO2, due to the far-reaching emissions (measured in billions of tonnes per year). Among the “greenhouse gases” with the far-reaching “global warming potential” (GWP) are the so-called “Ozone gases” or substances that damage the ozone layer CFC and HCFC. Fortunately, there is a far smaller amount of these gases that reaches the atmosphere than CO2.

Convective storms and non-classical low-level jets during high ozone level episodes in the Amazon region: An ARM/GOAMAZON case study

In this work, we investigate the ozone dynamics during the occurrence of both downdrafts associated with mesoscale convective storms and non-classical low-level jets. Extensive data sets, comprised of air chemistry and meteorological observations made in the Amazon region of Brazil over the course of 2014–15, are analyzed to address several questions. A first objective is to investigate the atmospheric thermodynamic and dynamic conditions associated with storm-generated ozone enhancements in the Amazon region. A second objective is to determine the magnitude and the frequency of ground-level ozone enhancements related to low-level jets. Ozone enhancements are analyzed as a function of wind shear, low-level jet maximum wind speed, and altitude of jet core. Strong and sudden increases in ozone levels are associated with simultaneous changes in variables such as horizontal wind speed, convective available potential energy, turbulence intensity and vertical velocity skewness. Rapid increases in vertical velocity skewness give support to the hypothesis that the ozone enhancements are directly related to downdrafts. Low-level jets associated with advancing density currents are often present during and after storm downdrafts that transport ozone-enriched air from aloft to the surface.

Potential Importance of Ozone in the Association Between Outdoor Air Pollution and Dry Eye Disease in South Korea.

Air pollution is an important public health concern and the ocular surface is continuously exposed to pollutants in outdoor air. Ocular surface abnormalities related to air pollution are thought to be a subtype of dry eye disease (DED). However, to date, there is no large-scale study evaluating an association between air pollution and DED that includes multiple air pollutants. To investigate associations between outdoor air pollution and DED in a Korean population. A population-based cross-sectional study using data on 16 824 participants in the fifth Korea National Health and Nutrition Examination Survey was conducted from January 1, 2010, to December 31, 2012. Data analysis was conducted from September 1 to 30, 2015. Dry eye disease was defined as previously diagnosed by an ophthalmologist or the presence of frequent ocular pain and discomfort. Outdoor air pollution measurements (mean annual humidity, particulate matter with aerodynamic diameter <10 µm [PM10], ozone, and nitrogen dioxide levels) were collected from 283 national monitoring stations in South Korea. Associations of multiple air pollutants with DED were assessed from multivariable logistic regression analyses. Sociodemographic factors and previously known factors associated with DED were applied as covariates (model 1 controlled for sociodemographic factors and model 2 controlled for sociodemographic, behavioral, and clinical factors). Among 16 824 participants (7104 men and 9720 women), higher ozone levels and lower humidity levels were significantly associated with symptoms and diagnosis of DED. In model 1, an increase in ozone levels of 0.003 ppm was significantly associated with symptoms and diagnosis of DED (symptoms: odds ratio [OR], 1.16; 95% CI, 1.02-1.30; P = .04; diagnosis: OR, 1.21; 95% CI, 1.05-1.40; P = .008), while a 5% increase in humidity levels was significantly associated with decreased symptoms and diagnoses of DED (symptoms: OR, 0.87; 95% CI, 0.77-0.98; P = .03; diagnosis: OR, 0.86; 95% CI, 0.76-0.97; P = .01). In model 2, an increase in ozone levels of 0.003 ppm was significantly associated with symptoms and diagnosis of DED (symptoms: OR, 1.17; 95% CI, 1.02-1.34; P = .03; diagnosis: OR, 1.27; 95 CI, 1.09-1.48; P = .002), while a 5% increase in humidity levels was significantly associated with decreased symptoms and diagnoses of DED (symptoms: OR, 0.88; 95% CI, 0.78-0.98; P = .045; diagnosis: OR, 0.86; 95% CI, 0.76-0.97; P = .02). In model 2, an increase in nitrogen dioxide of 0.003 ppm (OR, 1.12; 95% CI, 1.02-1.23 P = .02) was also associated with diagnosis of DED. Levels of sulfur dioxide and PM10 were not associated with symptoms or diagnosis of DED in model 1 or model 2 (P > .05 for each). Higher ozone levels and lower humidity levels were associated with DED in the Korean population, while PM10 level was not associated with DED.

Concentration Response Curve for Ozone related Mortality at High Concentrations

Background Rising temperatures and decreased global circulation in the upcoming decades are expected to have a detrimental impact on air quality, particularly with respect to ozone. The largest impacts are anticipated to occur in the form of the frequency and duration of summertime regional pollution episodes. These events are likely to induce nonlinear increases in ozone levels. Objective We examine concentration-response curve for ozone related mortality to evaluate the sensitivity of the health burden with respect to high end of ozone distribution. Methods A flexible Bayesian hierarchical model is developed to allow for the nonlinear ozone risk curve with a shape parameter controlling the prior belief about the monotonicity of the risk. We use polynomial spline basis functions and their derivatives to evaluate relative at different quantiles of the ozone distribution. The model was applied to the data from the US National Morbidity, Mortality, and Air Pollution Study for 95 major US urban centers between 1987 and 2000. Results were examined with respect to those obtained under the assumption of linear effect of ozone without positivity constraint (Bell et al, JAMA 2004). Results Under the assumption of linear effect of ozone relative risk is 0.12+-0.03%. Under moderate and strong monotonicity priors we estimate average log relative rate as 0.25+-0.06% and 0.56+-0.04% per 10ppb, respectively, across the interquartile range of maximum hourly Ozone concentrations. Above the 95% percentile of the ozone distribution these estimates double (0.57+-0.09% and 1.2+-0.05%). Conclusion Our preliminary results indicate that concentration-response relationship is not linear across all levels of ozone. Air pollution episodes are likely to impact high end of ozone distribution and thus contribute larger health burden per unit increase of ozone. Disclaimer: This abstract does not necessarily reflect U.S. EPA policy.

Modelling ozone levels in an arid region - a dynamically evolving soft computing approach

The primary pollutants may contribute to the increase of ozone levels in the arid regions. Complex interactions between the pollutants and the meteorological variables make the study of this phenomenon more exigent. The dynamically evolving neural fuzzy inference system (DENFIS), as an example of soft computing models, allows the online evolution of both the knowledge and the inference mechanism. It is suitable for real-time applications in producing fairly reliable forecasts. The proposed DENFIS model for two sites in the Empty Quarter (Rub Al-Khali Desert) of Saudi Arabia was developed using the meteorological data collected during the winter and the summer seasons, and the transformed meteorological data. The concentrations of nitrogen oxide (NOx) and their transformations were incorporated as additional inputs for model performance analyses. The mean absolute percentage errors of the model vary from 9.52% to 11.84% with discretion and appreciation of the limitations of the overall model predictions and its performance analyses indicate the viability of application of the adopted online DENFIS modelling approach in short-term modelling of zone levels in arid regions.

Changes in tropospheric ozone levels over the Three Representative Regions of China observed from space by the Tropospheric Emission Spectrometer (TES), 2005–2010

Tropospheric ozone observations over China from 2005 to 2010 at three pressure levels (484, 681 and 825 hPa) from the Tropospheric Emission Spectrometer on board the NASA Aura satellite have been analyzed. Fourier Transform analysis revealed the trends and seasonality of regionally-averaged, monthly-mean ozone concentrations over western, northern and southern China. Significant increases in ozone levels are found over all three regions at 464 hPa and the rate of increase is fastest over northern China, reaching 0.89±0.059 nL/(L a). At 681 hPa, ozone shows increases over northern and western China, at a rate of 0.57± 0.065 nL/(L a) and 0.41±0.041 nL/(L a) respectively, but is constant over southern China. At 825 hPa, ozone increases at a rate of 0.36±0.074 nL/(L a) over northern China, while decreasing over southern China at a rate of −0.21±0.061 nL/(L a). Over the three regions, ozone levels are generally higher in summer and lower in winter. Over southern China at all three pressure levels and northern China at the 825 hPa level, ozone shows double peaks occurring in spring and autumn as a result of the combined effects of atmospheric chemistry and global transport. This work provides a useful observational dataset and tools for future analysis of changes in tropospheric ozone over China.

A Modeling Study of the Impact of a Power Plant on Ground-Level Ozone in Relation to its Location: Southwestern Spain as a Case Study

The impact of atmospheric industrial emissions on secondary pollutant formation depends on many factors; one of the most important being the environmental setting in which the industry is located. The environmental setting affects an industry’s impact on ozone levels through both the air mass dispersion (a function of topography and wind patterns) and the emissions of organic volatile compounds (VOC) and nitrogen oxides (NOx) in the area. This model-based study shows how the sensitivity of surface ozone changes with the choice of source location. For the analysis, seven points distributed along the Tinto–Guadalquivir Basin (in the Southwestern Iberian Peninsula) were selected. This area is characterized by the close proximity of natural environments and crop fields to cities, roads, and industrial areas with high NOx emissions. Natural VOC emissions represent more than 60% of the total non-methane volatile organic compounds emitted in the study area. The results reveal that the largest increases in ozone levels are produced when the industry is located both far away from NOx emission sources and near to biogenic VOC emissions. Furthermore, the highest increases over the hourly and 8-hourly maximums, as well as the highest accumulated daily values, are found in areas characterized by high VOC/NOx emission ratios and NOx sensitivity. The study of the recurrent meteorological patterns along with the distribution of chemical indicators of the O3–NOx–VOC sensitivity allows the determination of the industry’s geographical impact on ozone levels. This information enables air quality managers to decide the future location of an industry minimizing its impact on smog levels.

Impact of climate change on tropospheric ozone and its global budgets

Abstract. We present the chemistry-climate model UMCAM in which a relatively detailed tropospheric chemical module has been incorporated into the UK Met Office's Unified Model version 4.5. We obtain good agreements between the modelled ozone/nitrogen species and a range of observations including surface ozone measurements, ozone sonde data, and some aircraft campaigns. Four 2100 calculations assess model responses to projected changes of anthropogenic emissions (SRES A2), climate change (due to doubling CO2), and idealised climate change-associated changes in biogenic emissions (i.e. 50% increase of isoprene emission and doubling emissions of soil-NOx). The global tropospheric ozone burden increases significantly for all the 2100 A2 simulations, with the largest response caused by the increase of anthropogenic emissions. Climate change has diverse impacts on O3 and its budgets through changes in circulation and meteorological variables. Increased water vapour causes a substantial ozone reduction especially in the tropical lower troposphere (&gt;10 ppbv reduction over the tropical ocean). On the other hand, an enhanced stratosphere-troposphere exchange of ozone, which increases by 80% due to doubling CO2, contributes to ozone increases in the extratropical free troposphere which subsequently propagate to the surface. Projected higher temperatures favour ozone chemical production and PAN decomposition which lead to high surface ozone levels in certain regions. Enhanced convection transports ozone precursors more rapidly out of the boundary layer resulting in an increase of ozone production in the free troposphere. Lightning-produced NOx increases by about 22% in the doubled CO2 climate and contributes to ozone production. The response to the increase of isoprene emissions shows that the change of ozone is largely determined by background NOx levels: high NOx environment increases ozone production; isoprene emitting regions with low NOx levels see local ozone decreases, and increase of ozone levels in the remote region due to the influence of PAN chemistry. The calculated ozone changes in response to a 50% increase of isoprene emissions are in the range of between −8 ppbv to 6 ppbv. Doubling soil-NOx emissions will increase tropospheric ozone considerably, with up to 5 ppbv in source regions.

Sensitivity analysis of tropospheric ozone to modified biogenic emissions for the Mid-Atlantic region

Biogenic sources contribute a large portion of emissions of volatile organic compounds (VOCs), a precursor to tropospheric ozone (O 3 ). These emissions are difficult to control and are affected by land-use and climate. A sensitivity analysis was performed using an emissions scenario with a 100% increase in biogenic emissions and another scenario with an additional 100% increase in motor vehicle emissions. Meteorological and air pollution models were used to generate hourly ozone estimates for a case study high ozone episode. Resulting concentration estimates correspond to the total effect of changes from emissions, incorporating the interaction between anthropogenic and biogenic emissions. Biogenic VOCs had a greater impact than a comparable percent increase in motor vehicle emissions of ozone precursors, in this case study. The 100% increase in biogenic VOC emissions raised ozone levels, with an estimated maximum 1-h concentration 30% higher than that of the baseline scenario. The additional emissions of ozone precursors from motor vehicles raised the maximum 1-h concentration 40% over that of the baseline. The largest increases in ozone concentrations occurred near peak values. Urban areas had larger increases in ozone levels than rural regions. Both adjusted emissions scenarios resulted in ozone concentrations lower than that of the baseline for some estimates. These reductions occurred near low ozone levels however and were generally small. This research demonstrates the importance of biogenic VOC emissions in ozone formation for this region and of biogenic emissions inventories. Results also imply that climate change-induced increases in biogenic VOC emissions could significantly impact ozone concentrations.

Virtual disjunct eddy covariance measurements of organic compound fluxes from a subalpine forest using proton transfer reaction mass spectrometry

Abstract. A `virtual' disjunct eddy covariance (vDEC) device was tested with field measurements of biogenic VOC fluxes at a subalpine forest site in the Rocky Mountains of the USA. A PTR-MS instrument was used as the VOC sensor. Daily peak emission fluxes of 2-methyl-3-buten-2-ol (MBO), methanol, acetone and acetaldehyde were around 1.5, 1, 0.8 and 0.4 mg m-2 h-1, respectively. High pass filtering due to long sampling lines was investigated in laboratory experiments, and suggested that VOC losses in PTFA lines are generally governed by diffusion laws. Memory effects and surface reactions did not seem to play a dominant role. Model estimates of MBO fluxes compared well with measured fluxes. The results also suggest that latent heat and sensible heat fluxes are reasonably well correlated with VOC fluxes and could be used to predict variations in VOC emissions. The release of MBO, methanol, acetone and acetaldehyde resulted in significant change of tropospheric oxidant levels and a 10--40% increase in ozone levels, as inferred from a photochemical box model. We conclude that vDEC with a PTR-MS instrument is a versatile tool for simultaneous field analysis of multiple VOC fluxes.

Microwave ozone and lidar aerosol profile observations at Table Mountain, California, following the Pinatubo eruption

Ozone profiles measured with a ground‐based microwave instrument in years from 1989 through 1992 at latitude 34°N. were searched for effects arising from the eruption of Mount Pinatubo in 1991. Between 20 and 24 km, ozone values after November 1991 were systematically less than in earlier years, and the deviation generally grew with time through May 1992. The minimum was 11 to 15% below values in earlier years, and occurred later than minima observed with ozonesondes at higher latitudes or predicted by some models. Although there was a steady increase in ozone levels in the 18–10 hPa range between February and May 1992, the highest values were not significantly above normal. Effects of the quasi‐biennial oscillation on ozone values are much smaller than the observed changes. Colocated lidar observations show that stratospheric aerosol levels were steadily elevated from November 1991 through at least March 1992, with some intermittent activity in late August through October 1991. The main aerosol cloud thus arrived at the same time as depletion first appeared.

Ozone control strategy modeling and evaluation for Athens, Greece: ROG vs. NO x effectiveness and the impact of using different wind field preparation techniques

The CIT photochemical model was used to investigate the effectiveness of ozone control strategies for Athens, Greece. A unique aspect of this study was the use of two different wind fields, one from a prognostic model, and the other derived with objective analysis procedures. This allows investigating to what degree the wind fields both derived using accepted methods, influence control strategy evaluation. Strategies investigated included reducing ROG and NO x , and combinations of the two. For the period studied, the use of different meteorological field preparation techniques did not influence the direction of the ozone response to controls. In both cases (i.e. using prognostic or objective analysis wind fields), reducing NO x led to predicted increases in ozone levels at the measurement stations, and ROG control lowered ozone. PAN concentrations respond similarly to ozone. However, use of the two different wind fields significantly impacted the degree and spatial locations of the responses. Use of the objective analysis fields showed greater response to emission controls because of the lower wind velocities generated. The influence of the biogenic emissions were found to be small. Also, a number of key data necessary for future studies of this kind were identified, as well as modeling domain questions.

Trends in surface ozone concentrations at Arosa (Switzerland)

During the years 1989–1991, ozone was measured at four sites around Arosa (Switzerland). One of these sites was identical with that, where surface ozone was measured in the 1950s (Götz and Volz, 1951; Perl, 1965). Comparison of both old and recent data indicates that surface ozone concentrations at Arosa have increased by a factor of approximately 2.2. The increase shows a seasonal variation with a relative increase of more than a factor of three in December and January. The results are discussed in the context of measurements made at other times, locations and altitudes. The comparison indicates that the increase in ozone levels at Arosa has most likely occured between the fifties and today. The measurements additionally suggest that photochemical ozone production in the free troposphere has significantly contributed to the observed ozone trends in winter.

The Ozone Hole, Dynamically Speaking

The Ozone Hole, Dynamically Speaking

Using Farmers’ Actions to Measure Crop Loss Due to Air Pollution

The effects of ozone on the profitability of Illinois cash grain farms is investigated by utilizing a profit function framework. This approach uses individual farms as the observational unit so the data are generated under field conditions. Hence, experimental plot data are not used although results from past biological experiments are utilized to frame initial hypotheses and for evaluation of the estimated model. This study demonstrates the benefits of combining economic data and biological science results to estimate the economic reactions of producers in terms of input and output (production) response to an ambient environmental characteristic. A time series of cross sectional data on cash grain farms in Illinois is used to estimate two profit functions. Ozone data are measured on a growing season basis by county. The estimated model shows ozone has a negative effect on profits. Increases in ozone levels tend to depress output levels and lessen the demand for variable inputs. Additionally, a production function is derived from one of the profit functions. The impact of ozone is found to be in general agreement with dose-response data obtained in Illinois by plant scientists.