Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a by-product of the very oxidation chemistry it largely initiates. Much effort is focussed on the reduction of surface levels of ozone owing to its health impacts but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve due to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate-change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner.

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Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

The nationwide extent of surface ozone pollution in China and its comparison to the global ozone distribution have not been recognized because of the scarcity of Chinese monitoring sites before 2012. Here we address this issue by using the latest 5 year (2013–2017) surface ozone measurements from the Chinese monitoring network, combined with the recent Tropospheric Ozone Assessment Report (TOAR) database for other industrialized regions such as Japan, South Korea, Europe, and the United States (JKEU). We use various human health and vegetation exposure metrics. We find that although the median ozone values are comparable between Chinese and JKEU cities, the magnitude and frequency of high-ozone events are much larger in China. The national warm-season (April–September) fourth highest daily maximum 8 h average (4MDA8) ozone level (86.0 ppb) and the number of days with MDA8 values of >70 ppb (NDGT70, 29.7 days) in China are 6.3–30% (range of regional mean differences) and 93–575% higher, respectively, than ...

Severe Surface Ozone Pollution in China: A Global Perspective

This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. Review pubs.acs.org/CR Multiphase Chemistry at the Atmosphere−Biosphere Interface Inﬂuencing Climate and Public Health in the Anthropocene Ulrich Po schl* and Manabu Shiraiwa* Multiphase Chemistry Department, Max Planck Institute for Chemistry, 55128 Mainz, Germany air contaminants (SHCC) and their multiphase chemical interactions at the atmosphere−biosphere interface, including human lungs and skin, plant leaves, cryptogamic covers, soil, and aquatic surfaces. After an overview of diﬀerent groups of SHCC, we address the chemical interactions of reactive oxygen species and reactive nitrogen species (ROS, RNS), primary biological and secondary organic aerosols (PBA, SOA), as well as carbonaceous combustion aerosols (CCA) including soot, black/elemental carbon, polycyclic aromatic hydrocarbons, and related compounds (PAH, PAC). ROS and RNS interact strongly with other SHCC and are central to both atmospheric and physiological processes and their coupling through the atmosphere−biosphere interface, for example, in the formation and aging of biogenic and combustion aerosols as well as in CONTENTS inﬂammatory and allergic immune responses triggered by air pollution. Deposition of atmospheric ROS/RNS and aerosols 1. Introduction and Motivation can damage biological tissues, modify surface microbiomes, and 2. Health- and Climate-Relevant Air Contaminants induce oxidative stress through Fenton-like reactions and 2.1. Reactive Oxygen and Nitrogen Species immune responses. The chemical mechanisms and kinetics are 2.2. Primary Biological Aerosols not yet fully elucidated, but the available evidence suggests that 2.3. Secondary Organic Aerosols multiphase processes are crucial for the assessment, prediction, 2.4. Carbonaceous Combustion Aerosols and handling of air quality, climate, and public health. Caution 2.5. Other Air Contaminants Linking Atmospher- should be taken to avoid that human activities shaping the ic and Physiological Chemistry Anthropocene create a hazardous or pathogenic atmosphere 3. Multiphase Chemical Reactions at Speciﬁc Bio- overloaded with allergenic, corrosive, toxic, or infectious logical Interfaces contaminants. 3.1. Lung Lining Fluid Multiphase chemistry deals with chemical reactions, trans- 3.2. Human Skin port processes, and transformations between gaseous, liquid, 3.3. Plant Surfaces and Cryptogamic Covers and solid matter. These processes are essential for Earth system 3.4. Soil and Aquatic Surfaces science and climate research as well as for life and health 4. Conclusions and Outlook sciences on molecular and global levels, bridging a wide range Author Information of spatial and temporal scales from below nanometers to Corresponding Authors thousands of kilometers and from less than nanoseconds to Notes years and millennia as illustrated in Figure 1. Biographies From a chemical perspective, life and the metabolism of most Acknowledgments living organisms can be regarded as multiphase processes References involving gases like oxygen and carbon dioxide; liquids like water, blood, lymph, and plant sap; and solid or semisolid substances like bone, tissue, skin, wood, and cellular 1. INTRODUCTION AND MOTIVATION membranes. Even primitive forms of life and metabolic activity Multiphase chemistry plays a vital role in the Earth system, under anaerobic conditions generally involve multiple liquid climate, and health. Chemical reactions, mass transport, and and solid or semisolid phases structured by cells, organelles, and phase transitions between gases, liquids, and solids are essential membranes. 2 On global scales, the biogeochemical cycling of for the interaction and coevolution of life and climate. chemical compounds and elements, which can be regarded as Knowledge of the mechanisms and kinetics of these processes the metabolism of planet Earth, also involves chemical is also required to address societally relevant questions of global reactions, mass transport, and phase transitions within and environmental change and public health in the Anthropocene, that is, in the present era of globally pervasive and steeply Special Issue: 2015 Chemistry in Climate increasing human inﬂuence on planet Earth. 1 In this work, we review the current scientiﬁc understanding and recent advances Received: September 1, 2014 in the investigation of short-lived health- and climate-relevant Published: April 9, 2015 © 2015 American Chemical Society DOI: 10.1021/cr500487s Chem. Rev. 2015, 115, 4440−4475

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Multiphase chemistry at the atmosphere-biosphere interface influencing climate and public health in the anthropocene.

Climate change and air pollution are critical environmental issues both in the here and now and for the coming decades. A recent OECD report found that unless action is taken, air pollution will be the largest environmental cause of premature death worldwide by 2050. Already, air pollution levels in Asia are far above acceptable levels for human health, and even in Europe, the vast majority of the urban population was exposed to air pollution concentrations exceeding the EU daily limit values, and especially the stricter WHO air quality guidelines in the past decade. The most recent synthesis of climate change research as presented in the fifth IPCC Assessment Report (AR5) states that the warming of the climate system is unequivocal, recognizing the dominant cause as human influence, and providing evidence for a 43% higher total (from 1750 to the present) anthropogenic radiative forcing (RF) than was reported in 2005 from the previous assessment report.

Chemistry and the Linkages between Air Quality and Climate Change.

Air pollution contributes to the premature deaths of millions of people each year around the world, and air quality problems are growing in many developing nations. While past policy efforts have succeeded in reducing particulate matter and trace gases in North America and Europe, adverse health effects are found at even these lower levels of air pollution. Future policy actions will benefit from improved understanding of the interactions and health effects of different chemical species and source categories. Achieving this new understanding requires air pollution scientists and engineers to work increasingly closely with health scientists. In particular, research is needed to better understand the chemical and physical properties of complex air pollutant mixtures, and to use new observations provided by satellites, advanced in situ measurement techniques, and distributed micro monitoring networks, coupled with models, to better characterize air pollution exposure for epidemiological and toxicological research, and to better quantify the effects of specific source sectors and mitigation strategies.

"What We Breathe Impacts Our Health: Improving Understanding of the Link between Air Pollution and Health"

Tropospheric ozone plays a major role in Earth’s atmospheric chemistry processes and also acts as an air pollutant and greenhouse gas. Due to its short lifetime, and dependence on sunlight and precursor emissions from natural and anthropogenic sources, tropospheric ozone’s abundance is highly variable in space and time on seasonal, interannual and decadal time-scales. Recent, and sometimes rapid, changes in observed ozone mixing ratios and ozone precursor emissions inspired us to produce this up-to-date overview of tropospheric ozone’s global distribution and trends. Much of the text is a synthesis of in situ and remotely sensed ozone observations reported in the peer-reviewed literature, but we also include some new and extended analyses using well-known and referenced datasets to draw connections between ozone trends and distributions in different regions of the world. In addition, we provide a brief evaluation of the accuracy of rural or remote surface ozone trends calculated by three state-of-the-science chemistry-climate models, the tools used by scientists to fill the gaps in our knowledge of global tropospheric ozone distribution and trends.

R. M. Zbinden

Papers

Global Distribution and Trends of Tropospheric Ozone: An Observation-Based Review