Ozone Levels Research Articles

Survey Response Analysis on the Use of Environmental Data for Sports Information Systems Development

Sport is primarily a mental and physical activity focused on competition with oneself, others, or the elements of nature—the contribution of sport to the modern world's social development, the nation, and the state. As history has shown, technical advancements have never diminished sports and linked to civilization's advancement in human life. Walking and bicycling are increasingly promoted as active modes of transportation and boosting physical activity levels. The elevated breathing rates in traffic microenvironments have generated worries about increased exposure to ultrafine particles. Amateur half marathoners did detrimental significantly when the temperature, heat index, and ozone levels rise. The athlete or recreational sportsperson can earn environmental information through several channels and devices. There are applications and widgets now embedded or separated from the device operating systems. This research aimed to find appropriate environmental information from recreational sportspeople's understanding and awareness of the environment's effect on sports performance. Walking (77) and running (48) were the most sports activities picked by the respondents. Then 99 (73%) respondents used environmental data before exercising. Weather (118) was the respondents' choice, followed by the temperature (47) and the air quality (30) picked by the respondents. Most respondents (72%) get environmental information from their smartphones, and 27 (18%) get it from the website. Environmental factors may impact sports activity performance, and the respondents used environmental information before the sports activities began. This research will later support the sports information system web application.

Prenatal ambient air pollutant mixture exposure and neurodevelopment in urban children in the Northeastern United States

BackgroundStudies of prenatal air pollution (AP) exposure on child neurodevelopment have mostly focused on a single pollutant. We leveraged daily exposure data and implemented novel data-driven statistical approaches to assess effects of prenatal exposure to a mixture of seven air pollutants on cognitive functioning in school-age children from an urban pregnancy cohort. MethodsAnalyses included 236 children born at ≥37 weeks gestation. Maternal prenatal daily exposure levels for nitrogen dioxide (NO2), ozone (O3), and constituents of fine particles [elemental carbon (EC), organic carbon (OC), nitrate (NO3−), sulfate (SO42−), ammonium (NH4+)] were estimated based on residential addresses using validated satellite-based hybrid models or global 3-D chemical-transport models. Children completed Wide Range Assessment of Memory and Learning (WRAML-2) and Conners’ Continuous Performance Test (CPT-II) at 6.5 ± 0.9 years of age. Time-weighted levels for mixture pollutants were estimated using Bayesian Kernel Machine Regression Distributed Lag Models (BKMR-DLMs), with which we also explored the interactions in the exposure-response functions among pollutants. Resulting time-weighted exposure levels were used in Weighted Quantile Sum (WQS) regressions to examine AP mixture effects on outcomes, adjusted for maternal age, education, child sex, and prenatal temperature. ResultsMothers were primarily ethnic minorities (81% Hispanic and/or black) reporting ≤12 years of education (68%). Prenatal AP mixture (per unit increase in WQS estimated AP index) was associated with decreased WRAML-2 general memory (GM; β = −0.64, 95%CI = −1.40, 0.00) and memory-related attention/concentration (AC; β = −1.03, 95%CI = −1.78, −0.27) indices, indicating poorer memory functioning, as well as increased CPT-II omission errors (OE; β = 1.55, 95%CI = 0.34, 2.77), indicating increased attention problems. When stratified by sex, association with AC index was significant among girls, while association with OE was significant among boys. Traffic-related pollutants (NO2, OC, EC) and SO42− were major contributors to these associations. There was no significant evidence of interactions among mixture components. ConclusionsPrenatal exposure to an AP mixture was associated with child neurocognitive outcomes in a sex- and domain-specific manner.

Evaluating the potential role of federal air quality standards in constraining applications of prescribed fire in the western United States

Prescribed fire is a useful tool for building resilient landscapes in fire-prone areas across the globe. In the western U.S., prescribed fire is employed by federal, state, and Tribal land managers and planned during particular meteorological and air quality conditions to manage air quality impacts. As agencies prepare to plan and permit more prescribed fire, an ongoing question will be whether existing air quality conditions constrain the potential for more prescribed fire. We performed a set of spatial and statistical analyses to evaluate how prescribed burns are potentially constrained by federal air quality standards. In doing so, we also examined if the answers to these questions differed when applied to different land management agencies that administer prescribed burns in the West. Analysis of the results shows that the geographic distribution of air quality conditions has not been constraining the implementation of prescribed fire plans, and climate change-driven changes to air quality, such as increasing ozone levels, may make prescribed burning more difficult under current air quality constraints. Furthermore, results demonstrated regional air quality issues for specific pollutants, suggesting an ongoing need for regional air quality assessments in the planning of prescribed burning across the western U.S.

Timing matters: Intra-day shifts of economic activity and ambient ozone concentrations

Ground-level ozone has been shown to have significant negative health externalities from short-term exposure, and as such has been regulated by the U.S. Clean Air Act since the 1970s. Ozone is not emitted directly; instead formation occurs due to a complex Leontief-like combination of air pollutants, under sunlight and warm temperatures, that results in high levels mid-day and low levels at night. Despite this known relationship, EPA regulations mostly consider the total emissions of ozone precursors and not when these emissions occur. Using hourly data on ambient ozone from 1980 to 2017 near the U.S. time zone borders, we provide evidence that the 1-hour time difference on either side of a border leads to a nontrivial change in ozone levels in certain hours of the day. We then examine a cap-and-trade program targeting ozone precursor emissions – the NOx Budget Program – finding that while it reduced ozone overall it did not have an economically significant effect on the timing of those emissions. We conclude by outlining a possible policy approach to account for the time-varying value of reductions in ozone precursor emissions.

Elevated ozone alters long-chain fatty acids in leaves of Japanese white birch saplings.

Long-chain fatty acids (LCFAs) in leaves have attracted attention as nutritious phytochemicals and olfactory signals that influence the behavior and growth of herbivorous insects. In recognition of the negative effects of increasing tropospheric ozone (O3) levels on plants, LCFAs can be altered through peroxidation by O3. However, how elevated O3 changes the amount and composition of LCFAs in field-grown plants is still unknown. We investigated palmitic, stearic, oleic, linoleic, linolenic LCFAs in the two leaf types (spring and summer) and two stages (early and late stage after expansion) of Japanese white birch (Betula platyphylla var. japonica) after a multi-year O3 exposure on the field. Summer leaves exhibited a distinct composition of LCFAs under elevated O3 at the early stage, whereas both stages of spring leaves did not exhibit significant changes in LCFAs composition by elevated O3. In the spring leaves, the amounts of saturated LCFAs significantly increased at the early stage, however, the amount of total, palmitic, and linoleic acids at the late stage were significantly decreased by elevated O3. Summer leaves had a lower amount of all LCFAs at both leaf stages. Regarding the early stage of summer leaves, the lower amount of LCFAs under elevated O3 was possibly due to O3-suppressed photosynthesis in the current spring leaves. Furthermore, the decrease ratio of spring leaves over time was significantly increased by elevated O3 in all LCFAs, whereas summer leaves did not exhibit such an effect. These findings suggest that further studies should be conducted to reveal the biological functions of LCFAs under elevated O3, considering the leaf type- and stage-dependent changes of LCFAs.

Are children with sickle cell disease at particular risk from the harmful effects of air pollution? Evidence from a large, urban/peri-urban cohort.

Pathophysiologic pathways of sickle cell disease (SCD) and air pollution involve inflammation, oxidative stress, and endothelial damage. It is therefore plausible that children with SCD are especially prone to air pollution's harmful effects. Patient data were collected from a single-center, urban/peri-urban cohort of children with confirmed SCD. Daily ambient concentrations of particulate matter (PM2.5 ) were collected via satellite-derived remote-sensing technology, and carbon monoxide (CO), nitrogen dioxide (NO2 ), and ozone from local monitoring stations. We used multivariable regression to quantify associations of pollutant levels and daily counts of emergency department (ED) visits, accounting for weather and time trends. For comparison, we quantified the associations of pollutant levels with daily all-patient (non-SCD) ED visits to our center. From 2010 to 2018, there were 17,731 ED visits by 1740 children with SCD (64.8% HbSS/HbSβ0 ). Vaso-occlusive events (57.8%), respiratory illness (17.1%), and fever (16.1%) were the most common visit diagnoses. Higher 3-day (lags 0-2) rolling mean PM2.5 and CO levels were associated with daily ED visits among those with SCD (PM2.5 incident rate ratio [IRR] 1.051 [95% confidence interval: 1.010-1.094] per 9.4μg/m3 increase; CO 1.088 [1.045-1.132] per 0.5ppm). NO2 showed positive associations in secondary analyses; ozone levels were not associated with ED visits. The comparison, all-patient ED visit analyses showed lower IRR for all pollutants. Our results suggest short-term air pollution levels as triggers for SCD events and that children with SCD may be more vulnerable to air pollution than those without SCD. Targeted pollution-avoidance strategies could have significant clinical benefits in this population.

Evolution of summer surface ozone pollution patterns in China during 2015–2020

Surface ozone is one of the most severe air pollutants in China and is influenced by meteorological processes on multiple scales. By identifying the two dominant patterns of ozone pollution through Empirical Orthogonal Functions method, we show here that the widespread pollution processes in China may be closely related to high-pressure anomaly in North China and low-pressure anomaly in the western Pacific, respectively. The positive time period of the first pattern (PC1P) extracts the distribution characteristics of the most severe periods of ozone pollution in summer time. It is physically linked to the high-pressure anomaly in North China centered on the Huanghuai Region, which eventually induced the high-temperature anomaly and low-humidity anomaly that enhanced the photochemical reactions to elevate the ozone levels. The spatial and temporal evolution of ozone pollution during this meteorological process shows a uniform pollution characteristic in the northern region and a higher increase in ozone concentration in the Huanghuai Region. The positive time period of the second pattern (PC2P) is associated with the variation of the low-pressure anomaly in the western Pacific. It indicates uniformly high ozone pollution in the south, especially in the Yangtze River Delta, the middle reaches of the Yangtze River (MYR) and the Pearl River Delta. Our results highlight that summer ozone pollution in eastern China is closely related to weather patterns. In addition, it is noteworthy that in the positive time period, the annual growth trends of Huanghuai Region in the first pattern (PC1P) and MYR in the second pattern (PC2P) are significantly higher than the growth trends of the megacity clusters, which requires the attention of relevant policy-making authorities.

Biocompatibility and Safety Assessment of Combined Topical Ozone and Antibiotics for Treatment of Infected Wounds.

Wound infections with antibiotic-resistant bacteria, particularly the Gram-negative strains, pose a substantial health risk for patients with limited treatment options. Recently topical administration of gaseous ozone and its combination with antibiotics through portable systems has been demonstrated to be a promising approach to eradicate commonly found Gram-negative strains of bacteria in wound infections. However, despite the significant impact of ozone in treating the growing number of antibiotic-resistant infections, uncontrolled and high concentrations of ozone can cause damage to the surrounding tissue. Hence, before such treatments could advance into clinical usage, it is paramount to identify appropriate levels of topical ozone that are effective in treating bacterial infections and safe for use in topical administration. To address this concern, we have conducted a series of in vivo studies to evaluate the efficacy and safety of a portable and wearable adjunct ozone and antibiotic wound therapy system. The concurrent ozone and antibiotics are applied through a wound interfaced gas permeable dressing coated with water-soluble nanofibers containing vancomycin and linezolid (traditionally used to treat Gram-positive infections) and connected to a portable ozone delivery system. The bactericidal properties of the combination therapy were evaluated on an ex vivo wound model infected with Pseudomonas aeruginosa, a common Gram-negative strain of bacteria found in many skin infections with high resistance to a wide range of currently available antibiotics. The results indicated that the optimized combination delivery of ozone (4 mg h-1) and topical antibiotic (200 μg cm-2) provided complete bacteria eradication after 6 h of treatment while having minimum cytotoxicity to human fibroblast cells. Furthermore, in vivo local and systemic toxicity studies (e.g., skin monitoring, skin histopathology, and blood analysis) on pig models showed no signs of adverse effects of ozone and antibiotic combination therapy even after 5 days of continuous administration. The confirmed efficacy and biosafety profile of the adjunct ozone and antibiotic therapy places it as a strong candidate for treating wound infection with antimicrobial-resistant bacteria and further pursuing human clinical trials.

Spatial variability of trace gases (NO2, O3 and CO) over Indian region during 2020 and 2021 COVID-19 lockdowns.

COVID-19 lockdown has given us an opportunity to investigate the pollutant concentrations in response to the restricted anthropogenic activities. The atmospheric concentration levels of nitrogen dioxide (NO2), carbon monoxide (CO) and ozone (O3) have been analysed for the periods during the first wave of COVID-19 lockdown in 2020 (25th March-31st May 2020) and during the partial lockdowns due to second wave in 2021 (25th March-15th June 2021) across India. The trace gas measurements from Ozone Monitoring Instrument (OMI) and Atmosphere InfraRed Sounder (AIRS) satellites have been used. An overall decrease in the concentration of O3 (5-10%) and NO2 (20-40%) have been observed during the 2020 lockdown when compared with business as usual (BAU) period in 2019, 2018 and 2017. However, the CO concentration increased up to 10-25% especially in the central-west region. O3 and NO2 slightly increased or had no change in 2021 lockdown when compared with the BAU period, but CO showed a mixed variation prominently influenced by the biomass burning/forest fire activities. The changes in trace gas levels during 2020 lockdown have been predominantly due to the reduction in the anthropogenic activities, whereas in 2021, the changes have been mostly due to natural factors like meteorology and long-range transport, as the emission levels have been similar to that of BAU. Later phases of 2021 lockdown saw the dominant effect of rainfall events resulting in washout of pollutants. This study reveals that partial or local lockdowns have very less impact on reducing pollution levels on a regional scale as natural factors like atmospheric long-range transport and meteorology play deciding roles on their concentration levels.

Indoor air quality in a training centre used for sports practice.

One of the measures for controlling the coronavirus disease 2019 (COVID-19) pandemic was the mass closure of gyms. This measure leads us to determine the differences between indoor and outdoor air quality. That is why the objective of this study was to analyse the indoor air quality of a sports centre catering to small groups and rehabilitation. The study was conducted in a single training centre, where 26 measurements were taken in two spaces (indoors and outdoors). The air quality index, temperature, relative humidity, total volatile compounds, carbon monoxide, ozone, formaldehyde, carbon dioxide, and particulate matter were measured indoors and outdoors using the same protocol and equipment. These measurements were taken twice, once in the morning and once in the afternoon, with all measurements made at the same time, 10 am and 6 pm, respectively. Additionally, four determinations of each variable were collected during each shift, and the number of people who had trained in the room and the number of trainers were counted. In the different variables analysed, the results show that CO2 and RH levels are higher indoors than outdoors in both measurement shifts. Temperatures are higher outside than inside and, in the evening, than in the morning. TVOC, AQI and PM show less variation, although they are higher outdoors in the morning. CO is highest indoors. HCHO levels are almost negligible and do not vary significantly, except for a slight increase in the afternoon outside. Ozone levels are not significant. All the variables showed practically perfect reliability in all the measurements, except for ozone measured outside in the morning. On the other hand, the variables exhibit variations between indoors and outdoors during the morning and afternoon, except for the three types of PM. Also, the data show that all the main variables measured inside the sports training centre are similar between morning and afternoon. However, outside, temperature, relative humidity and HCHO levels show significant differences between morning and afternoon while no differences are observed for the other variables. The indoor air quality of the training centre assessed was good and met current regulations; some of its components even exhibited better levels than fresh air. This article is the first to measure indoor air quality in a sports training centre catering to rehabilitation and small groups.

Effects of Climate Change and Air Pollution on Perinatal Health.

Climate change is often framed as an environmental concern; however, the burning of fossil fuels both directly and indirectly impacts air quality and, thus, human health. Gas byproducts of combustion lead to increased levels of atmospheric ozone and carbon dioxide, which in turn elevate surface temperatures of the earth. This process exposes individuals to respiratory irritants and contributes to increased frequency of natural disasters such as wildfires, negatively impacting respiratory health. Normal physiologic changes in the respiratory system make pregnant people particularly vulnerable to the effects of air pollution. Asthma and allergic rhinitis are 2 common respiratory diseases that can be triggered by poor air quality. Solutions to limit the impact of climate change on respiratory disease include risk mitigation and reduction of fossil fuel consumption on individual, organization, and community levels. Midwives are well positioned as clinicians to educate people about individual strategies to reduce environmental exposure to respiratory irritants and advocate for policy changes to limit future health effects of climate change.

Protectants to ameliorate ozone-induced damage in crops – A possible solution for sustainable agriculture

Elevated levels of tropospheric ozone (O3) are phytotoxic, inhibiting plant growth and production, and thus, compromising environmental health and sustainable crop production. It is therefore critical to devise strategies to protect plants from the negative effects of O3. However, the efficacy of different chemical or non-chemical methods to protect plants against O3 toxicities has not been critically reviewed. Hence, this study aimed at comprehensively reviewing various methods of crop protection against O3 stress. Ethylenediurea (EDU) is the most investigated and efficient protectant in ameliorating O3-induced phytodamage. However, plant protectants (e.g. pesticides, fungicides), antitranspirants (e.g. di-1-p-menthene), antioxidants (e.g. ascorbic acid, diphenylamine), exogenously-applied plant hormones (e.g. ethylene, kinetin, abscisic acid), and nutrient management strategies (e.g. varied level of nitrogen fertilizers, application of calcium acetate) were also found to offer some protection against O3. Hence, more studies are needed to comprehensively explore the potential of these methods, individually and in different combinations. Biological mechanisms that underlie the ameliorative effect of the different methods are discussed along with relevance of the concept of hormesis. This assessment also acknowledges major information gaps and suggests future options for dealing with O3 pollution. New insights into the efficacy of additional protectants provide a new dimension to plant protection against O3-induced detrimental effects, and suggest that future research should use a green chemistry approach and an ‘one health’ perspective.

Fitting Statistical Distribution Functions of Air Pollutant Concentration in Different Urban Locations in Malaysia

Ground level ozone is an unstable substance in the atmosphere which reacts with nitrogen dioxide (NOx) in the presence of sunlight normally found near ground level. Ground level ozone is known as one of the major air quality issues worldwide. The presence of the NOx volatile organic compounds (VOCs) can influence the concentration levels of ground level ozone. This pollutant can affect crops and human health. The main aim of this research is to find the best fit distribution for urban monitoring stations in Kuala Terengganu, Kota Bharu and Alor Setar. Secondary data from 2011 to 2015 used in this study was obtained from the Department of Environment (DOE). This research used the central fitting probability distribution which is between gamma, Nakagami, lognormal and log logistic distributions. Meanwhile, the method of moments was used to estimate the parameters. The best distribution represented the monitoring station and predicted the return period of the concentration. The results show that the Nakagami distribution represented the Kuala Terengganu station from 2011 to 2015. In Kota Bharu however, the gamma distribution fit better compared to other distributions in 2013. The gamma distribution seems to fit the data from 2011 to 2014 whereas in 2015, the Nakagami distribution fit better than other distributions for the Alor Setar station. In addition, no return period was predicted for concentrations above 0.10 ppm found at the Kuala Terengganu monitoring station.

The impacts of ambient ozone pollution on China's wheat yield and forest production from 2010 to 2021

Near-surface ozone causes damages on both crop and forest but their long-term spatiotemporal changes in China have been insufficiently explored, preventing comprehensive policy making with food security and climate targets. Moreover, limitation exists in the current metrics for long-term regional ozone risk assessment, AOT40 (the accumulated hourly ozone over a threshold of 40 ppbv) and PODY (phytotoxic ozone dose over a threshold of Y nmol ozone m−2 PLA s−1), with ignorance of meteorological influence for the former and complicated data collection and calculation procedures for the latter. Here, we developed a new metric for ozone-induced risk on winter wheat, O3MET, which can be easily derived based on ozone concentrations and meteorological variables, and is suitable for long-term assessment of ozone-induced wheat loss at the regional scale. Combining with existing metric for forest (O3RH), we comprehensively quantified the ozone damages on winter wheat yield and forest gross primary production (GPP) for mainland China during 2010–2021, the period with fast growth of ozone level across the country. The annual average losses of wheat yield and forest GPP were estimated at 26.5 Mt and 552.6 TgC, accounting for 17% and 4% of the total yield and GPP without ozone impact, respectively. Heavy dual ozone-induced damages on both wheat and forest were presented in East and South China. The ozone-induced wheat yield loss and forest GPP loss were estimated to increase at a rate of 1.8 Mt/yr and 13.9 TgC/yr for the entire country, respectively, driven mainly by the enhanced ambient ozone level within the research period. Besides ecological impact, the ozone pollution in the developed eastern China resulted in serious health burden as well, thus effective actions on ozone pollution alleviation in the region is crucial for reducing its ecological and health risks simultaneously.

Elevated ozone and carbon dioxide affects the composition of volatile organic compounds emitted by Vicia faba (L.) and visitation by European orchard bee (Osmia cornuta).

Recent studies link increased ozone (O3) and carbon dioxide (CO2) levels to alteration of plant performance and plant-herbivore interactions, but their interactive effects on plant-pollinator interactions are little understood. Extra floral nectaries (EFNs) are essential organs used by some plants for stimulating defense against herbivory and for the attraction of insect pollinators, e.g., bees. The factors driving the interactions between bees and plants regarding the visitation of bees to EFNs are poorly understood, especially in the face of global change driven by greenhouse gases. Here, we experimentally tested whether elevated levels of O3 and CO2 individually and interactively alter the emission of Volatile Organic Compound (VOC) profiles in the field bean plant (Vicia faba, L., Fabaceae), EFN nectar production and EFN visitation by the European orchard bee (Osmia cornuta, Latreille, Megachilidae). Our results showed that O3 alone had significant negative effects on the blends of VOCs emitted while the treatment with elevated CO2 alone did not differ from the control. Furthermore, as with O3 alone, the mixture of O3 and CO2 also had a significant difference in the VOCs' profile. O3 exposure was also linked to reduced nectar volume and had a negative impact on EFN visitation by bees. Increased CO2 level, on the other hand, had a positive impact on bee visits. Our results add to the knowledge of the interactive effects of O3 and CO2 on plant volatiles emitted by Vicia faba and bee responses. As greenhouse gas levels continue to rise globally, it is important to take these findings into consideration to better prepare for changes in plant-insect interactions.

The future ozone trends in changing climate simulated with SOCOLv4

Abstract. This study evaluates the future evolution of atmospheric ozone simulated with the Earth system model (ESM) SOCOLv4. Simulations have been performed based on two potential shared socioeconomic pathways (SSPs): the middle-of-the-road (SSP2-4.5) and fossil-fueled (SSP5-8.5) scenarios. The future changes in ozone, as well as in chemical drivers (NOx and CO) and temperature, were estimated between 2015 and 2099 and for several intermediate subperiods (i.e., 2015–2039, 2040–2069, and 2070–2099) via dynamic linear modeling. In both scenarios, the model projects a decline in tropospheric ozone in the future that starts in the 2030s in SSP2-4.5 and after the 2060s in SSP5-8.5 due to a decrease in concentrations of NOx and CO. The results also suggest a very likely ozone increase in the mesosphere and the upper and middle stratosphere, as well as in the lower stratosphere at high latitudes. Under SSP5-8.5, the ozone increase in the stratosphere is higher because of stronger cooling (>1 K per decade) induced by greenhouse gases (GHGs), which slows the catalytic ozone destruction cycles. In contrast, in the tropical lower stratosphere, ozone concentrations decrease in both experiments and increase over the middle and high latitudes of both hemispheres due to the speeding up of the Brewer–Dobson circulation, which is stronger in SSP5-8.5. No evidence was found of a decline in ozone levels in the lower stratosphere at mid-latitudes. In both future scenarios, the total column ozone is expected to be distinctly higher than present in middle to high latitudes and might be lower in the tropics, which causes a decrease in the mid-latitudes and an increase in the tropics in the surface level of ultraviolet radiation. The results of SOCOLv4 suggest that the stratospheric-ozone evolution throughout the 21st century is strongly governed not only by a decline in halogen concentration but also by future GHG forcing. In addition, the tropospheric-ozone column changes, which are mainly due to the changes in anthropogenic emissions of ozone precursors, also have a strong impact on the total column. Therefore, even though the anthropogenic halogen-loading problem has been brought under control to date, the sign of future ozone column changes, globally and regionally, is still unclear and largely depends on diverse future human activities. The results of this work are, thus, relevant for developing future strategies for socioeconomic pathways.

Narrowing Differences in Urban and Nonurban Surface Ozone in the Northern Hemisphere Over 1990–2020

Surface ozone air pollution is unequally distributed in space and varies over urban and surrounding nonurban areas. Traditionally, urban ozone levels tend to be lower than their nonurban counterparts, resulting from discrepancies in emissions and nonlinearity in photochemistry. However, how the differences in urban vs nonurban ozone evolve over the past decades is uncertain. Here, we construct 6361 pairs of urban and nonurban ozone measurement sites based on available surface monitoring networks to analyze the long-term changes of their ozone differences. We show that urban vs nonurban ozone differences have narrowed substantially in North America, Europe, South Korea, and Japan over the summers of 1990–2020. The hemispheric mean urban vs nonurban ozone differences have decreased by 90% from −5.0 ppbv in the 1990s to −0.5 ppbv in the 2010s. We estimate that the anthropogenic emission reduction of nitrogen oxides is the dominant driver of the narrowing trends. It has suppressed the urban ozone titration and led to closer ozone formation regimes over urban and nonurban areas.

The influence of vegetation drought stress on formaldehyde and ozone distributions over a central European city

To estimate the effect of vegetation stress and changes in biogenic volatile organic compound (BVOC) emissions on urban ozone (O3) levels we perform a systematic, observation-based analysis of the relationship between formaldehyde (HCHO) mixing ratios, meteorological parameters, measurement-based drought indicators and O3 over the central European city of Vienna, Austria. In addition, numerical models SURface EXternalisée (SURFEX), Model of Emissions of Gases and Aerosols from Nature (MEGAN) Vers.2.1 and 3 and MOdèle de Chimie A Grande Echelle (MOCAGE) are combined to estimate the soil moisture, the spatial distribution and drought response of isoprene emissions, and the resulting distribution of HCHO in the atmosphere. To analyse the effect of drought during spring and summer we contrast observations during dry and reference years. Our results show that the observed HCHO can be explained using the simulated isoprene emissions as well as observed and simulated vegetation drought responses. HCHO mixing ratios differ strongly between dry and reference seasons. Spring-time precipitation deficits facilitate reduced HCHO mixing ratios due to delayed and weakened plant growth. In consequence also O3 burdens are lowered due to reduced BVOC precursor emissions. These reductions occur despite radiation levels being higher than during the reference year, illustrating the strong potential of spring-time BVOC emissions to modulate urban O3 burdens. Conversely, during summer elevated O3 levels occur during local drought conditions. These are driven by advected isoprene originating from nearby forest areas, which are not affected by drought. Our results regarding elevated summer-time O3 burdens under vegetation heat and drought stress are in good agreement with previous work.

Silicic and Ascorbic Acid Induced Modulations in Photosynthetic, Mineral Uptake, and Yield Attributes of Mung Bean (Vigna radiata L. Wilczek) under Ozone Stress.

Most of the world's crop production and plant growth are anticipated to be seriously threatened by the increasing tropospheric ozone (O3) levels. The current study demonstrates how different mung bean genotypes reacted to the elevated level of O3 in the presence of exogenous ascorbic and silicic acid treatments. It is the first report to outline the potential protective effects of ascorbic and silicic acid applications against O3 toxicity in 12 mung bean {Vigna radiata (L.) Wilken} varieties. Under controlled circumstances, the present investigation was conducted in a glass house. There were four different treatments used: control (ambient O3 concentration of 40-45 ppb), elevated O3 (120 ppb), elevated O3 with silicic acid (0.1 mM), and elevated O3 with ascorbic acid (10 mM). Three varieties, viz. NM 20-21, NM 2006, and NM 2016, showcased tolerance to O3 toxicity. Our findings showed that ascorbic and silicic acid applications gradually increased yield characteristics such as seed yield, harvest index, days to maturity, and characteristics related to gas exchange such as transpiration rate, stomatal conductance, net photosynthetic activity, and water-use efficiency. Compared to the control, applying both growth regulators enhanced the mineral uptake across all treatments. Based on the findings of the current study, it is concluded that the subject mung bean genotypes responded to silicic acid treatment more efficiently than ascorbic acid to mitigate the harmful effects of O3 stress.

Spatiotemporal characteristics of ozone and the formation sensitivity over the Fenwei Plain

High surface ozone (O3) levels affect human and environmental health. The Fenwei Plain (FWP), one of the critical regions for China's “Blue Sky Protection Campaign”, has reported severe O3 pollution. This study investigates the spatiotemporal properties and the causes of O3 pollution over the FWP using high-resolution data from the TROPOspheric Monitoring Instrument (TROPOMI) from 2019 to 2021. This study characterizes spatial and temporal variations in O3 concentration by linking O3 columns and surface monitoring using a trained deep forest machine learning model. O3 concentrations in summer were 2–3 times higher than those found in winter due to higher temperatures and greater solar irradiation. The spatial distributions of O3 correlate with the solar radiation showing decreased trends from the northeastern to the southwestern FWP, with the highest O3 values in Shanxi Province and the lowest in Shaanxi Province. For urban areas, croplands and grasslands, the O3 photochemistry in summer is NOx-limited or in the transitional regime, while it is VOC-limited in winter and other seasons. Reducing NOx emissions would be effective for decreasing O3 levels in summer, while VOC reductions are necessary for winter. The annual cycle in vegetated areas included both NOx-limited and transitional regimes, indicating the importance of NOx controls to protect ecosystems. The O3 response to limiting precursors shown here is of importance for optimizing control strategies and is illustrated by emission changes during the 2020 COVID-19 outbreak.