Ambient O3 Research Articles

Measurement report: Photochemical production and loss rates of formaldehyde and ozone across Europe

Abstract. Various atmospheric sources and sinks regulate the abundance of tropospheric formaldehyde (HCHO), which is an important trace gas impacting the HOx (≡ HO2 + OH) budget and the concentration of ozone (O3). In this study, we present the formation and destruction terms of ambient HCHO and O3 calculated from in situ observations of various atmospheric trace gases measured at three different sites across Europe during summertime. These include a coastal site in Cyprus, in the scope of the Cyprus Photochemistry Experiment (CYPHEX) in 2014, a mountain site in southern Germany, as part of the Hohenpeißenberg Photochemistry Experiment (HOPE) in 2012, and a forested site in Finland, where measurements were performed during the Hyytiälä United Measurements of Photochemistry and Particles (HUMPPA) campaign in 2010. We show that, at all three sites, formaldehyde production from the OH oxidation of methane (CH4), acetaldehyde (CH3CHO), isoprene (C5H8) and methanol (CH3OH) can almost completely balance the observed loss via photolysis, OH oxidation and dry deposition. Ozone chemistry is clearly controlled by nitrogen oxides (NOx ≡ NO + NO2) that include O3 production from NO2 photolysis and O3 loss via the reaction with NO. Finally, we use the HCHO budget calculations to determine whether net ozone production is limited by the availability of VOCs (volatile organic compounds; VOC-limited regime) or NOx (NOx-limited regime). At the mountain site in Germany, O3 production is VOC limited, whereas it is NOx limited at the coastal site in Cyprus. The forested site in Finland is in the transition regime.

The Effects of Ozone on Visual Attraction Traits of Erodium paularense (Geraniaceae) Flowers: Modelled Perception by Insect Pollinators.

Ozone (O3) effects on the visual attraction traits (color, perception and area) of petals are described for Erodium paularense, an endangered plant species. Plants were exposed to three O3 treatments: charcoal-filtered air (CFA), ambient (NFA) and ambient + 40 nL L−1 O3 (FU+) in open-top chambers. Changes in color were measured by spectral reflectance, from which the anthocyanin reflectance index (ARI) was calculated. Petal spectral reflectance was mapped onto color spaces of bees, flies and butterflies for studying color changes as perceived by different pollinator guilds. Ozone-induced increases in petal reflectance and a rise in ARI under NFA were observed. Ambient O3 levels also induced a partial change in the color perception of flies, with the number of petals seen as blue increasing to 53% compared to only 24% in CFA. Butterflies also showed the ability to partially perceive petal color changes, differentiating some CFA petals from NFA and FU+ petals through changes in the excitation of the UV photoreceptor. Importantly, O3 reduced petal area by 19.8 and 25% in NFA and FU+ relative to CFA, respectively. In sensitive species O3 may affect visual attraction traits important for pollination, and spectral reflectance is proposed as a novel method for studying O3 effects on flower color.

Invasive herbaceous respond more negatively to elevated ozone concentration than native species

AbstractAimMany studies show that increase in ground‐level ozone (O3) has adverse effects on plant growth. Due to high phenotypic plasticity, invasive species is considered to be more adaptable to elevated O3 than native species. This idea is only tested by the very limited studies comparing invasive weeds with crops. However, whether it holds remains unclear when comparing invasive species with their co‐occurring native species in natural systems.LocationChina.MethodsWe performed an open‐top chamber experiment growing six congeneric pairs of invasive and native species with and without competition under ambient (approximately 43 ppb) and elevated O3 (approximately 89 ppb) concentrations to test whether the growth responses to elevated O3 concentrations differ between invasive and native species.ResultsOur results revealed that elevated O3 had a significant negative effect on both invasive and native species. In particular, elevated O3 reduced the aboveground biomass and damaged the leaves of invasive species significantly more than those of native species.Main conclusionsOur study indicates that elevated O3 concentration has a stronger adverse effect on invasive species than on native species. Therefore, increasing O3 pollution might suppress plant invasion, and thus invasive species might expand their distribution more easily to the area with lower O3 pollution in the future.

Diurnal Variations in Physiological Characteristics, Photoassimilates, and Total Ascorbate in Early and Late Sown Indian Wheat Cultivars under Exposure to Elevated Ozone

Rising tropospheric ozone (O3) in the atmosphere is detrimental to crop’s productivity and is one of the reasons for a warmer climate. The present study describes diurnal changes in gaseous exchange, chlorophyll fluorescence, ascorbic acid, and photoassimilate parameters in flag leaves of four Indian wheat (Triticum aestivum L.) cultivars (two early sown and two late sown cultivars) under ambient and elevated O3 treatments, using the open-top chambers (OTCs). Results showed that the diurnal pattern of photosynthetic rate (Ps), sucrose, and ascorbic acid content varied according to changes in photosynthetically active radiation (PAR) and O3 concentrations during the daytime and were maximum between 10:00 to 12:00. The present study suggested that elevated O3 caused more negative effects on photosystem II in early sown compared to late sown cultivars. The greater loss of photosynthesis led to lower production of photoassimilates in early sown cultivars, which utilized more assimilates in ascorbic acid formation for detoxification of ROS formed due to elevated O3. This work will also help to identify the robustness of physiological machinery in different wheat cultivars under elevated levels of O3, and may be used for selection of suitable cultivars during future breeding programs.

Novel Method for Ozone Isopleth Construction and Diagnosis for the Ozone Control Strategy of Chinese Cities.

Ozone (O3) isopleths describe the nonlinear responses of O3 concentrations to changes in nitrogen oxides (NOX) and volatile organic compounds (VOCs) and thus are pivotal to the determination of O3 control requirements. In this study, we innovatively use the Community Multiscale Air Quality model with the high-order decoupled direct method (CMAQ-HDDM) to simulate O3 pollution of China in 2017 and derive O3 isopleths for individual cities. Our simulation covering the entire China Mainland suggests severe O3 pollution as 97% of the residents experienced at least 1 day, in 2017, in excess of Chinese Level-II Ambient Air Quality Standards for O3 as 160 μg·m-3 (81.5 ppbV equally). The O3 responses to emissions of precursors vary widely across individual cities. Densely populated metropolitan areas such as Jing-Jin-Ji, Yangtze River Delta, and Pearl River Delta are following NOX-saturated regimes, where a small amount of NOX reduction increases O3. Ambient O3 pollution in the eastern region generally is limited by VOCs, while in the west by NOX. The city-specific O3 isopleths generated in this study are instrumental in forming hybrid and differentiated strategies for O3 abatement in China.

RANS simulation of near-field dispersion of reactive air pollutants

In conventional modeling of air pollution dispersion, pollutants are treated as passive scalars or inert species even though most of them are chemically reactive [1]. Chemical reactions contribute to pollutant dispersion via the generation and depletion of pollutants, in addition to other two mechanisms: advection and turbulent diffusion. This study investigated how chemical reactions affect near-field pollution dispersion by integrating the simple NOx-O3 chemistry into RANS-based computational fluid dynamics (CFD) simulation. CFD simulation was used to model a mixed emission of NO and NO2 from a short stack attached to a building into ambient O3, prompting chemical reactions between the NO, NO2, and O3. Various degrees of chemical reactivity were modeled by varying the Damkhöler number (Da) between 0.073 and 4.363. The results showed significant chemical reactivity for cases where Da [NO] > 1, while cases with Da [NO] < 1 had pollutant dispersion patterns similar to inert species. Noticeable modifications in concentrations were detected at ground level, where the NO concentration was depleted and NO2 concentration increased significantly. A budget analysis revealed major contributions of chemistry and turbulent diffusion to plume dispersion in the surroundings, while advection mainly carried the pollutants downstream from the source.

Grid-based spatiotemporal modeling of ambient ozone to assess human exposure using environmental big data

Ozone (O3) pollution in China is increasing. It is the primary pollutant in summer and ambient O3 can lead to serious health problems for the public. Therefore, characterizing the spatiotemporal distribution of O3 is required for better environmental management and human exposure assessment. Statistical models, especially those based on machine learning, can be more convenient to use than chemical transport models and have shown improved accuracy. However, the quality of data affects model precision especially at fine spatiotemporal scales. Web-based environmental data can improve the spatial and temporal resolution of modeling data. This study applied high spatiotemporal resolution source information and emission inventories based on point of interest and real-time traffic data in a fine scale grid network to predict the O3 concentrations and assess the human exposure within Chengdu, China. The results showed that the web-based environmental data could be combined with statistical models such as random forest in air quality modeling. The model precision was high, especially at finer spatiotemporal scales. The R2 of the hourly and daily maximum 8-h mean concentrations of O3 models built in this study were 0.83 and 0.91 for sample-based cross-validation, and 0.79 and 0.90 for site-based cross-validation, respectively. Meteorological variables had the greatest impact on O3 concentrations especially sea-level pressure, temperature, vapor pressure, and humidity. People within the research area had a relatively high exposure level to pollutants over a longer time scale in the summer and spring. Findings from this work provide a good reference for related research on modeling air quality, and human health risk assessment using environmental big data.

Ethylenediurea (EDU) spray effects on willows (Salix sachalinensis F. Schmid) grown in ambient or ozone-enriched air: implications for renewable biomass production

Ground-level ozone (O3) is a widespread air pollutant causing extensive injuries in plants. However, its effects on perennial energy crops remain poorly understood due to technical difficulties in cultivating fast-growing shrubs for biomass production under O3 treatment on the field. Here we present the results of a two-year evaluation in the framework of which willow (Salix sachalinensis F. Schmid) shrubs were exposed to ambient (AOZ) or elevated (EOZ) O3 in two successive growing seasons (2014, 2015) and treated with 0 (EDU0) or 400 mg L−1 (EDU400) ethylenediurea spray in the second growing season. In 2014, EOZ altered the chemical composition of both top young and fallen leaves, and a novel mechanism of decreasing Mg in fallen leaves while highly enriching it in young top leaves was revealed in shrubs exposed to EOZ. In 2015, EDU400 alleviated EOZ-induced decreases in leaf fresh mass to dry mass ratio (FM/DM) and leaf mass per area (LMA). While EDU400 protected against EOZ-induced suppression of the maximum rate at which leaves can fix carbon (Amax) in O3-asymptomatic leaves, it did not alleviate EOZ-induced suppression of the maximum rates of carboxylation (VCmax) and electron transport (Jmax) and chlorophylls a, b, and a + b in the same type of leaves. In O3-symptomatic leaves, however, EDU400 alleviated EOZ-induced suppression of chlorophylls a and a + b, indicating different mode of action of EDU between O3-asymptomatic and O3-symptomatic leaves. Extensive herbivory occurred only in AOZ-exposed plants, leading to suppressed biomass production, while EOZ also led to a similar suppression of biomass production (EDU0 × EOZ vs. EDU400 × EOZ). In 2016, carry-over effects were also evaluated following cropping and transplantation into new ambient plots. Effects of EOZ in the preceding growing seasons extended to the third growing season in the form of suppressed ratoon biomass production, indicating carry-over effect of EOZ. Although EDU400 protected against EOZ-induced suppression of biomass production when applied in 2015, there was no carry-over effect of EDU in the absence of EDU treatment in 2016. The results of this study provide novel mechanistic understandings of O3 and EDU modes of action and can enlighten cultivation of willow as energy crop.

Modeling of the health impacts of ambient ozone pollution in China and India

Ground-level ozone (O3) pollution has become an increasingly prominent environmental problem in China and India, causing serious negative health effects. Based on the global fine-resolution simulation of O3 concentrations and epidemiological results, O3 pollution and corresponding mortalities were evaluated at provincial-level across China and India. Our results revealed that the population-weighted mean O3 concentrations in China and India were 49.2 and 63.4 ppb, respectively, in 2014. The annual deaths attributable to O3 exposure were estimated to be 76,000 (95% confidence interval (CI): 27,000–120,000) and 96,000 (35,000–149,000) in China and India, respectively. The finding of 32.2% less O3-attributable mortality in China than in India was attributed to the combined effects of population size (+39.4%), population aging (+29.2%), baseline mortality rate (−43.7%), and ambient O3 exposure (−57.1%). To the best of our knowledge, this is the first time that O3-related health burdens in China and India have been reported and compared at the provincial level. The results will improve our understanding of O3-related health impacts and provide a valuable reference for policy makers.

Chronic ozone exposure preferentially modifies root rather than foliar metabolism of date palm (Phoenix dactylifera) saplings

In their natural environment, date palms are exposed to chronic atmospheric ozone (O3) concentrations from local and remote sources. In order to elucidate the consequences of this exposure, date palm saplings were treated with ambient, 1.5 and 2.0 times ambient O3 for three months in a free-air controlled exposure facility. Chronic O3 exposure reduced carbohydrate contents in leaves and roots, but this effect was much stronger in roots. Still, sucrose contents of both organs were maintained at elevated O3, though at different steady states. Reduced availability of carbohydrate for the Tricarboxylic acid cycle (TCA cycle) may be responsible for the observed reduced foliar contents of several amino acids, whereas malic acid accumulation in the roots indicates a reduced use of TCA cycle intermediates. Carbohydrate deficiency in roots, but not in leaves caused oxidative stress upon chronic O3 exposure, as indicated by enhanced malonedialdehyde, H2O2 and oxidized glutathione contents despite elevated glutathione reductase activity. Reduced levels of phenolics and flavonoids in the roots resulted from decreased production and, therefore, do not indicate oxidative stress compensation by secondary compounds. These results show that roots of date palms are highly susceptible to chronic O3 exposure as a consequence of carbohydrate deficiency.

Relationships between Long-Term Ozone Exposure and Allergic Rhinitis and Bronchitic Symptoms in Chinese Children.

Numerous studies have demonstrated that exposure to ambient ozone (O3) could have adverse effects on children’s respiratory health. However, previous studies mainly focused on asthma and wheezing. Evidence for allergic rhinitis and bronchitic symptoms (e.g., persistent cough and phlegm) associated with O3 is limited, and results from existing studies are inconsistent. This study included a total of 59,754 children from the seven northeastern cities study (SNEC), who were aged 2 to 17 years and from 94 kindergarten, elementary and middle schools. Information on doctor-diagnosed allergic rhinitis (AR), persistent cough, and persistent phlegm was collected during 2012–2013 using a standardized questionnaire developed by the American Thoracic Society (ATS). Information for potential confounders was also collected via questionnaire. Individuals’ exposure to ambient ozone (O3) during the four years before the investigation was estimated using a satellite-based random forest model. A higher level of O3 was significantly associated with increased risk of AR and bronchitic symptoms. After controlling for potential confounders, the OR (95% CI) were 1.13 (1.07–1.18), 1.10 (1.06–1.16), and 1.12 (1.05–1.20) for AR, persistent cough, and persistent phlegm, respectively, associated with each interquartile range (IQR) rise in O3 concentration. Interaction analyses showed stronger adverse effects of O3 on AR in children aged 7–17 years than those aged 2–6 years, while the adverse association of O3 with cough was more prominent in females and children aged 7–12 years than in males and children aged 2–6 and 13–17 years. This study showed that long-term exposure to ambient O3 was significantly associated with higher risk of AR and bronchitic symptoms in children, and the association varies across age and gender. Our findings contribute additional evidence for the importance of controlling O3 pollution and protecting children from O3 exposure.

Ozone Exposure, Outdoor Physical Activity, and Incident Type 2 Diabetes in the SALSA Cohort of Older Mexican Americans.

Background:Type 2 diabetes is a leading contributor to the global burden of morbidity and mortality. Ozone () exposure has previously been linked to diabetes.Objective:We studied the impact of exposure on incident diabetes risk in elderly Mexican Americans and investigated whether outdoor physical activity modifies the association.Methods:We selected 1,090 Mexican American participants from the Sacramento Area Latino Study on Aging conducted from 1998 to 2007. Ambient exposure levels were modeled with a land-use regression built with saturation monitoring data collected at 49 sites across the Sacramento metropolitan area. Using Cox proportional hazard models, we estimated the risk of developing incident diabetes based on average exposure modeled for 5-y prior to incident diabetes diagnosis or last follow-up. Further, we estimated outdoor leisure-time physical activity at baseline and investigated whether higher vs. lower levels modified the association between exposure and diabetes.Results:In total, 186 incident diabetes cases were identified during 10-y follow-up. Higher levels of physical activity were negatively associated with incident diabetes [ (95% CI: 0.43, 0.95)]. The estimated HRs for incident diabetes was 1.13 (95% CI: 1.00, 1.28) per 10-ppb increment of 5-y average exposure; also, this association was stronger among those physically active outdoors [ (95% CI: 1.21, 1.90)], and close to null for those reporting lower levels of outdoor activity [ (95% CI: 0.90, 1.20), ].Conclusions:Our findings suggest that ambient exposure contributes to the development of type 2 diabetes, particularly among those with higher levels of leisure-time outdoor physical activity. Policies and strategies are needed to reduce exposure to guarantee that the health benefits of physical activity are not diminished by higher levels of pollution in susceptible populations such as older Hispanics. https://doi.org/10.1289/EHP8620

Temporal variations of ambient air pollutants and meteorological influences on their concentrations in Tehran during 2012–2017

BACKGROUND AND AIM: In 2015, air pollution exposure was responsible for approximately nine million premature deaths; 16% of all deaths globally. In this study, we examined long-term air quality status in Tehran. METHODS: Here the temporal variations (hourly, daily, monthly, seasonal, and annual) of key criteria air pollutants (PM2.5, PM10 NO2, O3, SO2, CO) concentration and their relation to metrological parameters, as well as annual trends of air quality index (AQI) were investigated based on real-time hourly measurements of twenty-one air quality monitoring stations (AQMSs). RESULTS:Tehran citizens were consistently exposed to annual PM2.5, PM10 and NO2 approximately 3.0–4.5, 3.5–4.5 and 1.5–2.5 times higher than the World Health Organization air quality guideline levels during the period. Except for O3, all air pollutants demonstrated the lowest and highest concentrations in summertime and wintertime, respectively. The highest O3 concentrations were found on weekend (weekend effect), whereas other ambient air pollutants had statistically significant (P 0.05) daily variations in which higher concentrations were observed on weekdays compared to weekend (holiday effect). Hourly O3 concentration reached its peak at 3.00 p.m., though other air pollutants displayed two peaks; morning and late night. Approximately 45% to 65% of AQI values were in the subcategory of unhealthy for sensitive groups and PM2.5 was the responsible air pollutant in Tehran. Amongst meteorological factors, temperature was the key influencing factor for PM2.5 and PM10 concentrations, while nebulosity and solar radiation exerted major influences on ambient SO2 and O3 concentrations. Additionally, there is a moderate coupling between wind speed and NO2 and CO concentrations. CONCLUSIONS:Despite years of efforts for air quality improvement in Tehran, our results clearly confirm that ambient PM2.5 and PM10 are still the most notable air pollutants in this city. This represents that traffic-related policy measures for air quality improvement were not sufficiently efficacious in Tehran, particularly concerning reducing PM2.5 and PM10. KEYWORDS: Temporal trends, Criteria air pollutants, Meteorological parameters, AQI

Ozone Gas Inhibits SARS-CoV-2 Transmission and Provides Possible Control Measures

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused millions of deaths currently. Mounting effective responses to the pandemic have become top priorities for governments around the world. Laboratory experiments have confirmed for the first time that fumigation with ozone (O3) at low O3 doses (7500–15,000 μg m−3·min) can inhibit the SARS-CoV-2 and inactivate the virus at high O3 doses (129,000 μg m−3·min). The RNA copy number of SARS-CoV-2 significantly decreased (95.9–97.7% reduction) when exposed to O3 at a low concentration of 250 μg m−3 for 30 and 60 min. A significant negative relationship between the numbers of confirmed SARS-CoV-2 cases and ambient O3 in Chinese cities indicated that the spread of SARS-CoV-2 may have been inhibited by high O3. An analysis of data from Chongqing showed that the transmission of COVID-19 increased when the O3 mixing ratios in the air were relatively low, and transmission decreased when O3 increased. Based on these findings, we also propose a new Safety O3 Emission (SOE) method to increase indoor O3 to levels (< 160 μg m−3) that inhibit the transmission of the SARS-CoV-2 but are not harmful for humans. This could serve as timely and low-cost solution for suppressing COVID-19 outbreaks throughout the world.

Oxidation of Proteinaceous Matter by Ozone and Nitrogen Dioxide in PM2.5: Reaction Mechanisms and Atmospheric Implications

AbstractInteractions between proteinaceous matter and atmospheric oxidants can affect amino acids (AAs) bioavailability, the climate, and human health. However, atmospheric reactions of proteinaceous matter remain poorly understood. PM2.5 samples were collected during spring (2019) and winter (2020) sampling campaigns conducted in Nanchang, China. Concentrations of combined and free AAs, and the δ15N values of combined and free glycine (C‐Gly and F‐Gly) in PM2.5 samples were analyzed. Concentrations of TFAA under different O3 and NO2 levels, and correlations of specific FAA species with ambient O3 and NO2 concentrations suggest that the ability of O3 to release TFAA from proteinaceous matter is greater than that of NO2. Furthermore, O3 may trend to release neutral and hydrophilic FAA species, whereas NO2 tends to generate hydrophobic FAA species. With aerosol aging, the slope of the fitted line between [TFAA] and [TSAA] [O3 + NO2] increased, indicating that FAAs yield from protein degradation in PM2.5 was affected greatly by aerosol aging. The TCAAs concentration observed in spring was substantially higher than that in winter. Moreover, the δ15NF‐Gly and δ15NC‐Gly values in PM2.5 exhibited negative correlations with atmospheric O3 concentration. These results suggest that increased levels of proteinaceous matter in spring were derived from natural sources related to biological activities rather than biomass burning sources. Our study confirms that the reaction of degradation of proteinaceous matter to FAAs could be influenced by aerosol aging, which is a finding that enhances current understanding regarding atmospheric processes of aerosol proteinaceous matter under different ambient O3 and NO2 levels.

Characterizing the Aging of Alphasense NO2 Sensors in Long-Term Field Deployments

Low-cost NO2 sensors have been widely deployed for atmospheric sampling. While their initial performance has been characterized, few studies have examined their long-term degradation. This study focused on the performance of Alphasense low-cost NO2 sensors (NO2-B42F and NO2-B43F) over 4 years (2016-2020). A total of 29 NO2 sensors from 10 batches were collocated 78 times at two sites with reference instruments. Raw signals from "functional" NO2 sensors correlated linearly with reference NO2 concentrations. After long-term deployment, sensor raw signals started to deviate from reference NO2 concentrations due to sensor aging, an accumulated effect after sensor unpacking. Several sensors eventually became "non-functional" as sensor raw signals showed no correlation with reference NO2 concentrations. Sensor aging and non-functionality may be primarily caused by expiration of the ozone (O3) scrubber built into these sensors so that sensors responded to both ambient NO2 and O3. The influence of O3 on sensor response is quantified through the permutation importance method. Most of the sensors are non-functional after approximately 200-400 days of deployment, and no sensor was functional after 400 days of deployment. This result agrees well with the estimated lifetime of the built-in ozone scrubbers considering the ambient ozone concentration in the Pittsburgh area where these sensors were deployed. To ensure reliable data quality in long-term field deployments, we recommend collocating NO2 sensors with reference instruments regularly after 200-400 days of deployment to identify and replace non-functional sensors in a timely manner.

Elucidating the impacts of rapid urban expansion on air quality in the Yangtze River Delta, China

Urban expansion not only results in land use transformation, but also introduces extra anthropogenic emissions over the expanded urban areas, which is usually neglected in existing studies. In this study, we consider both the changes in land use categories and added anthropogenic emissions from 2001 to 2018 in the Yangtze River Delta (YRD) which we define as the city of Shanghai and the nearby provinces of Zhejiang, Jiangsu, and Anhui, China and explore the individual and combined impacts of these factors on air pollution using the WRF-Chem model. Calibrated by available observations, the model performs well (IOA (index of agreement) > 0.8) in reproducing the meteorological fields and ambient PM2.5 and O3 concentrations in September 2018. We show that the land use transformation from non-urban to urban and the introduced anthropogenic emissions over new urban areas exert opposite influences on ambient PM2.5 concentrations over YRD, particularly in the expanded urban areas, and the PM2.5 decrease due to land use changes is significantly offset by the increase due to added emissions. The response of ambient O3 concentration to these two factors is highly variable in space, which is dependent on the chemical regime of tropospheric O3 formation and influenced by the chemistry-meteorology feedback. As the total effect, strong increases in O3 concentration occur over the central areas of YRD. These results highlight that it is essential to take into account the additional anthropogenic emissions over expanded urban areas in the assessment of environmental impacts of urban expansion.

Source impact and contribution analysis of ambient ozone using multi-modeling approaches over the Pearl River Delta region, China

Quantification of source impacts and contributions is a key element for the design of effective air pollution control policies. In this study, O3 source impacts and contributions were comprehensively assessed over the Pearl River Delta (PRD) region of China using brute-force method (BFM), response surface modeling with BFM (RSM-BFM) and differential method (RSM-DM) respectively, high-order decoupled direct method (HDDM), and ozone source apportionment technology (OSAT). The multi-modeling comparison results indicated that under typical nonlinear atmospheric conditions during the O3 formation, BFM, RSM-BFM, and HDDM seemed to be appropriate for assessing the impact of single source emissions; however, the results of HDDM could deviate from those of BFM when the emission reduction ratio was higher than 50 %. Under multi-source control scenarios, the results of source contribution analyses obtained from RSM-DM and OSAT were reasonably well, but the performance of OSAT was limited by its capability in representing the nonlinearity of O3 response to emission reductions of its precursors, particularly NOx. The results of this pilot study in the PRD showed that the RSM-DM appeared to replicate the nonlinearity of O3 chemistry reasonably well (e.g., O3 disbenefits due to local NOx emission reductions in Guangzhou city). Based on the source contribution results, on-road mobile (including both NOx and VOC emissions) and industrial process (mainly VOC emissions) sources were identified as two major contribution sectors by both RSM-DM and OSAT, contributing an average of 31.5 % and 11.4 % (estimated by RSM-DM) and 29.2 % and 13.0 % (estimated by OSAT) respectively to O3 formation in 9 cities of the PRD. Therefore, the reinforced emission reductions on NOx and VOC from on-road mobile and industrial process sources in the central cities (i.e., Guangzhou, Foshan, Dongguan, Shenzhen, and Zhongshan) were suggested to effectively mitigate the ambient O3 levels in the PRD.

Sepsis-related hospital admissions and ambient air pollution: a time series analysis in 6 Chinese cities

BackgroundSome prevalent but rarely studied causes of hospital admissions, such as sepsis is still unknown whether affected by air pollution.MethodsWe used time-series regression within generalized additive models to estimate the effect of air pollutant level on the sepsis-related hospital admissions, for the years 2017–18, using data from six cities in Sichuan, China. Potential effect modifications by age and sex were also explored. The effects of air pollutant on hospital stays for sepsis were also quantified.ResultsPositive associations between short-term exposure to NO2 and O3 and risk of sepsis-related hospital admissions and stays were found. Each 10 μg/m3 increase in short-term NO2 at lag 03 and O3 at lag 4 was associated with an increase of 2.76% (95% CI: 0.67, 4.84%) and 0.64% (95% CI: 0.14, 1.14%) hospital admissions, respectively. An increase of 0.72% (95% CI: 0.05, 1.40%) hospital stay was associated with 10 μg/m3 increase in O3 concentration at lag 4. Besides, the adverse effect of exposure to NO2 was more significant in males and population aged less than 14 years; while more significant in females and population aged 14 ~ 65 and over 65 years for exposure to O3. These associations remained stable after the adjustment of other air pollutants.8.ConclusionExposure to ambient NO2 and O3 may cause substantial sepsis hospitalizations, and hospital stays in Sichuan, China. These associations were different in subgroup by age and sex.

Interactive effect of elevated tropospheric ozone and carbon dioxide on radiation utilisation, growth and yield of chickpea (Cicer arietinum L.).

An experiment was conducted in the Free Air Ozone and Carbon dioxide Enrichment (FAOCE) facility to study the impact of elevated O3, CO2 and their interaction on chickpea crop (cv. Pusa-5023) in terms of phenology, biophysical parameters, yield components, radiation interception and use efficiency. The crop was exposed to elevated O3 (EO:60ppb), CO2 (EC:550 ppm) and their combined interactive treatment (ECO: EC+EO) during the entire growing season. Results revealed that the crop's total growth period was shortened by 10, 14 and 17 days under elevated CO2, elevated O3 and the combined treatment, respectively. Compared to ambient condition, the leaf area index (LAI) under elevated CO2 was higher by 4 to 28%, whilst it is reduced by 7.3 to 23.8% under elevated O3. Theyield basedradiation use efficiency (RUEy) was highest under elevated CO2 (0.48 g MJ-1), followed by combined (0.41 g MJ-1), ambient (0.38 g MJ-1) and elevated O3 (0.32 g MJ-1) treatments. Elevated O3 decreased RUEy by 15.78% over ambient, and the interaction results in a 7.8% higher RUEy. The yield was 31.7% more under elevated CO2 and 21.9% lower in elevated O3 treatment as compared to the ambient. The combined interactive treatment recorded a higher yield as compared to ambient by 9.7%. Harvest index (HI) was lowest under elevated O3 (36.10%), followed by ambient (39.18%), combined (40.81%), and highest was under elevated CO2 (44.18%). Chickpea showed a positive response to elevated CO2 resulting a 5% increase in HI as compared to ambient condition. Our findings quantified the positive and negative impacts of elevated O3, CO2 and their interaction on chickpea and revealed that the negative impacts of elevated O3 can be compensated by elevated CO2 in chickpea. This work promotes the understanding of crop behaviour under elevated O3, CO2 and their interaction, which can be used as valuable inputs for radiation-based crop simulation models to simulate climate change impact on chickpea crop.