Isotopic constraint on the twentieth-century increase in tropospheric ozone.

Tropospheric ozone (O3) is a key component of air pollution and an important anthropogenic greenhouse gas1. During the twentieth century, the proliferation of the internal combustion engine, rapid industrialization and land-use change led to a global-scale increase in O3 concentrations2,3; however, the magnitude of this increase is uncertain. Atmospheric chemistry models typically predict4-7 an increase in the tropospheric O3 burden of between 25 and 50 per cent since 1900, whereas direct measurements made in the late nineteenth century indicate that surface O3 mixing ratios increased by up to 300 per cent8-10 over that time period. However, the accuracy and diagnostic power of these measurements remains controversial2. Here we use a record of the clumped-isotope composition of molecular oxygen (18O18O in O2) trapped in polar firn and ice from 1590 to 2016 AD, as well as atmospheric chemistry model simulations, to constrain changes in tropospheric O3 concentrations. We find that during the second half of the twentieth century, the proportion of 18O18O in O2 decreased by 0.03 ± 0.02 parts per thousand (95 per cent confidence interval) below its 1590-1958 AD mean, which implies that tropospheric O3 increased by less than 40 per cent during that time. These results corroborate model predictions of global-scale increases in surface pollution and vegetative stress caused by increasing anthropogenic emissions of O3 precursors4,5,11. We also estimate that the radiative forcing of tropospheric O3 since 1850 AD is probably less than +0.4 watts per square metre, consistent with results from recent climate modelling studies12.

Oleozón Tópico en el blanqueamiento de dientes con tratamiento pulporradicular: a propósito de un caso / Topical Oleozone in tooth bleaching with pulp-radicular treatment. A propos of a case

Introducción: sus dientes pueden cambiar de color por causas extrínsecas como la ingestión de café, vino, refrescos de cola o de otras bebidas que contengan colorantes, alimentos que pueden mancharlos y el tabaco, o por causas intrínsecas, cuando la estructura interna del diente (la dentina) se oscurece o toma un tinte amarillo como ocurre en ocasiones en dientes con tratamientos pulporradiculares. Presentación de caso: paciente femenina de 14 años de edad con antecedentes de buena salud que es traída a consulta por presentar cambio de color a nivel de 11 que afecta su estética y relaciones sociales, refiriendo su mamá que hace 5 años sufrió un golpe en dicho diente y se le realizó tratamiento pulporradicular por lo que se ingresa en los servicios de Estomatología para su valoración y tratamiento. Discusión: previa radiografía que corrobora la realización de forma correcta del tratamiento pulporradicular, se procede a la aplicación del Oleozón tópico con bolilla de algodón colocada en la cavidad (dentro del diente) de 1 a 3 minutos en sesiones de 10 minutos y aplicación de calor. Como criterios de evaluación se tuvieron el blanqueamiento del diente, la presencia o no de dolor y las radiografías periapicales. Conclusiones: luego de 3 sesiones se logró el blanqueamiento del diente con la aplicación del Oleozón tópico mejorando la estética y calidad de vida de la paciente(AU)

Introduction: your teeth may change their color due to some extrinsic causes such as the ingestion of coffee, wine, Coca Cola soft drinks or other drinks that contain dyes; foods that may stain them, or they also may change due to intrinsic causes, when the internal structure of the tooth (dentine) darkens or takes a yellow tint as it sometimes occurs in teeth with pulp radicular treatments. Case report: a 14 year-old-female patient with a good health antecedents, who was brought to the medical office due to a color change at the level of 11 that affects its aesthetic and social relations, her mother referred that 5 years ago her daughter suffered a stroke in that tooth and a pulp radicular treatment was performed to her, that it the reason why she was admitted in the Stomatology services for a further assessment and treatment. Discussion: previous radiography corroborating the correct performance of the pulp radicular treatment, it was also applied the topical Oleozone with a purified cotton placed in the cavity (inside the tooth) for 1-3 minutes in sessions of 10 minutes under heating. As the evaluation criteria it was considered the tooth whitening, the presence or absence of pain and periapical radiographies. Conclusions: after 3 sessions, the tooth whitening was achieved with the application of topical Oleozone improving the aesthetics and quality of life of the patient(EU)

Unprecedented Arctic ozone loss in 2011.

Chemical ozone destruction occurs over both polar regions in local winter-spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was--for the first time in the observational record--comparable to that in the Antarctic ozone hole. Unusually long-lasting cold conditions in the Arctic lower stratosphere led to persistent enhancement in ozone-destroying forms of chlorine and to unprecedented ozone loss, which exceeded 80 per cent over 18-20 kilometres altitude. Our results show that Arctic ozone holes are possible even with temperatures much milder than those in the Antarctic. We cannot at present predict when such severe Arctic ozone depletion may be matched or exceeded.

The history of ozone. Part VIII. Photochemical formation of ozone.

The historical development of the photochemical formation of ozone in the atmosphere is outlined, starting from the discovery of ozone by Schönbein in 1843 and the postulation of its role as UV filter by Hartley in 1881.

Critical considerations in evaluating scientific evidence of health effects of ambient ozone: a conference report.

The U.S. Environmental Protection Agency (EPA), under the authority of the Clean Air Act (CAA), is required to promulgate National Ambient Air Quality Standards (NAAQSs) for criteria air pollutants, including ozone. Each NAAQS includes a primary health-based standard and a secondary or welfare-based standard. This paper considers only the science used for revision of the primary standard for ozone in 2008. This paper summarizes deliberations of a small group of scientists who met in June 2007 to review the scientific information informing the EPA Administrator's proposed revision of the 1997 standard. The Panel recognized that there is no scientific methodology that, in the absence of judgment, can define the precise numerical level, related averaging time, and statistical form of the NAAQS. The selection of these elements of the NAAQS involves policy judgments that should be informed by scientific information and analyses. Thus, the Panel members did not feel it appropriate to offer either their individual or collective judgment on the specific numerical level of the NAAQS for ozone. The Panel deliberations focused on the scientific data available on the health effects of exposure to ambient concentrations of ozone, controlled ozone exposure studies with human volunteers, long-term epidemiological studies, time- series epidemiological studies, human panel studies, and toxicological investigations. The deliberations also dealt with the issue of background levels of ozone of nonanthropogenic origin and issues involved with conducting formal risk assessments of the health impacts of current and prospective levels of ambient ozone. The scientific issues that were central to the EPA Administrator's 2008 revision of the NAAQS for ozone will undoubtedly also be critical to the next review of the ozone standard. That review should begin very soon if it is to be completed within the 5-year cycle specified in the CAA. It is hoped that this Report will stimulate discussion of these scientific issues, conduct of additional research, and conduct of new analyses that will provide an improved scientific basis for the policy judgment that will have to be made by a future EPA Administrator in considering potential revision of the ozone standard.

Ozone and its usage in general medicine and dentistry. A review article.

Ozone, an allotropic form of oxygen, is successfully used in the treatment of different diseases for more than a hundred years. It is highly valued for various effects, such as antimicrobial, antihypoxic, analgesic, immunostimulating etc. on biological systems. These mechanisms of action supported with a lot of case reports and scientific studies allow using it in different fields of medicine. This review of literature is another attempt to summarize different modalities of ozone application in dentistry. Further studies are necessary to standardize indications and treatment protocols of this promising medical agent.

Ozonised oils as disinfectants.

In the ozone fervour of the mid-nineteenth century, the ability of ether, turpentine, and other unsaturated oils to take up oxygen was construed in terms of ozone, and the products were styled "ozonised ether" and "ozonised oils." Their undoubted oxidising power led to their use as disinfectants, notably by Dr. John Day in Australia, and Charles Kingzett in England and later America. Kingzett's "Sanitas" products enjoyed great popularity, and their properties were ascribed to fixed ozone, although the researches of Kingzett and others showed that the key components were hydroperoxides that may have given rise to hydrogen peroxide in solution.