Ambient O3 Research Articles

Impacts of ethylenediurea (EDU) soil drench and foliar spray in Salix sachalinensis protection against O3-induced injury

It is widely accepted that elevated levels of surface ozone (O3) negatively affect plants. Ethylenediurea (EDU) is a synthetic substance which effectively protects plants against O3-caused phytotoxicity. Among other questions, the one still open is: which EDU application method is more appropriate for treating fast-growing tree species. The main aims of this study were: (i) to test if chronic exposure of Salix sachalinensis plants to 200–400mgEDUL−1, the usually applied range for protection against O3 phytotoxicity, is beneficial to plants; (ii) to evaluate the effects of chronic exposure to elevated O3 on S. sachalinensis; (iii) to assess the efficacy of two methods (i.e. soil drench and foliar spray) of EDU application to plants; (iv) to investigate the appropriate concentration of EDU to protect against elevated O3-induced damage in S. sachalinensis; and (v) to compare the two methods of EDU application in terms of effectiveness and EDU consumption. Current-year cuttings grown in infertile soil free from organic matter were exposed either to low ambient O3 (AOZ, 10-h≈28.3nmolmol−1) or to elevated O3 (EOZ, 10-h≈65.8nmolmol−1) levels during daylight hours. Over the growing season, plants were treated every nine days with 200mL soil drench of 0, 200 or 400mgEDUL−1 or with foliar spray of 0, 200 or 400mgEDUL−1 (in two separate experiments). We found that EDU per se had no effects on plants exposed to AOZ. EOZ practically significantly injured S. sachalinensis plants, and the impact was indifferent between the experiments. EDU did not protect plants against EOZ impact when applied as soil drench but it did protect them when applied as 200–400mgL−1 foliar spray. We conclude that EDU may be more effective against O3 phytotoxicity to fast-growing species when applied as a spray than when applied as a drench.Keymessage: Soil-drenched EDU was ineffective in protecting willow plants against O3-induced injury, whereas foliar-sprayed EDU was effective even at the concentration of 200mgL−1.

Major heat waves of 2003 and 2006 and health outcomes in Prague

We have investigated the association between heat waves and mortality and hospital admissions for Prague inhabitants for the summer heat waves of August 2003 and July 2006. The effect of heat waves was investigated using negative binomial regression in a generalized additive model. We used a linear model on a logarithmic scale, having 1-day lagged temperature differences from the long-term average, 1-day lagged ambient O3 and PM10 concentration, relative humidity, simple “heat wave” indicator, and smooth seasonal effect as explanatory variables. We found a small increase in daily mortality for the examined period. This increase can be attributed to PM10 concentrations in most cases, and in fewer instances, to air temperature and O3 concentrations. The “heat wave” indicator did not significantly increase the relative risk; the same held for the relative humidity. For the general unstratified population, the highest increase in relative risk of 1.072 (95% CI 1.001–1.147) was observed for cardiovascular mortality and was associated with an increase in temperature of 10 °C, followed by an increase in relative risk of 1.056 (95% CI 1.025–1.087) for respiratory mortality associated with an increase in O3 concentrations by 10 μg.m−3. A higher risk in most cases was found for women. A significant increase of relative risk of 1.013 (95 % CI 1.002–1.024) due to PM10 was found for hospital admissions for cardiovascular causes. This issue should be studied further in view of the anticipated increase in meteorological extremes, including heat waves, in the future, to prepare prevention plans for eliminating their negative effects as far as possible.

Elevated ozone effects on soil nitrogen cycling differ among wheat cultivars

Elevated O3 (eO3) has strong effects on natural and managed ecosystems, including decreased plant growth, plant tissue quality, species richness, plant litter inputs, decomposition, and root turnover. However, the effects of eO3 on soil nitrogen (N) cycling are poorly understood. Here, a free -air O3 enrichment experiment was conducted from 2007 to 2012, in which two O3-tolerant wheat cultivars and two O3-sensitive cultivars were grown under ambient O3 (aO3, 40 ppb) and eO3 (60 ppb). We used a 15N pool dilution technique to investigate N transformation rates and N availability in the soils in 2012. Both gross and net N transformation rates were significantly decreased (P<0.05) by eO3 in soils growing sensitive wheat cultivars, but were unchanged in soils growing tolerant cultivars. Compared with aO3, NH4+ and NO3− concentrations were significantly increased (P<0.05) by eO3 in soils growing sensitive cultivars but not in soils growing tolerant cultivars. Ammonia monooxygenase activity was significantly increased by eO3 while nitrate reductase activity was significantly decreased. Additionally, redundancy analysis (RDA) suggested that microbial community structure was largely shaped by soil and plant characteristics such as DOC, root C/N ratio, MBC/MBN, shoot/root ratio, root N, soil N and pH. In conclusion, wheat cultivars play an important role in determining the effects of elevated O3 on N transformations. This study provides new insights into our understanding of how changes in microbial diversity and metabolism as mediated by plants will alter N cycling and ecosystem N availability in response to eO3 and suggests that these effects will differ among different plants.

Peak flow rate and its association with asthma, respiratory symptoms and weekly ambient air pollutants among 14 years old schoolchildren in Malaysia

Introduction: This cross sectional study aims to investigate the associations between peak flow rate and demographic factors, respiratory symptoms and weekly ambient air pollutants among schoolchildren (n=487) in Malaysia. Methods: Information on health were collected using the ISAAC related-questionnaire, and peak flow rate among the 14 year old schoolchildren were taken using the Sibelmed’s peak flow meter from Spain. Bivariate and multivariate analyses were done to identify the associations and risk factors for peak flow rate. Results: Overall peak expiratory rate of the schoolchildren were 329 L/min +-SD 55 L/min (minimum 180 L/min and maximum 560 L/min). Schoolchildren’s demographic data showed that gender (p&lt;0.000), school’s exposure (p=0.001) and smoking status (p&lt;0.000) were associated with peak flow rate. However, respiratory symptoms (wheezing and whistling, ever had asthma, doctor-diagnosed asthma, daytime and nocturnal breathlessness, current asthma and current airway infection) were not associated with peak flow rate. Peak flow rate was significantly correlated with weekly mean ambient air pollutants, CO (r=-0.134, p=0.003), O3 (r=-0.157, p=0.001), NO2 (r=0.145, p=0.001) and temperature (r=0.127, p=0.005). Multivariate regression analysis, shows that gender (R2=0.175) (beta=0.399,p &lt;0.000), weekly mean O3 (R2=0.200) (beta=-0.189, p&lt;0.000), weekly mean SO2 (R2=0.217) (beta=-0.128, p=0.002), and smoking status (R2=0.227) (beta=0.106, p=0.012) were predictors in peak flow rate after adjusting for other confounders. Conclusion: Schoolchildren’s lung function is linked with their demographic factors and weekly air pollutants but not respiratory symptoms. Peak flow rate could be considered a useful tool in lung function studies among Malaysian schoolchildren who are exposed to air pollutants. However, the duration of exposure to ambient air pollutants among the schoolchildren should be further analyzed.

Ozone and PM2.5 in the air pollution mixture differentially impact cardiopulmonary pathophysiologic mechanisms

Introduction: The relative contributions of ozone (O3) and PM2.5 in air pollution mixtures to cardiopulmonary outcomes remain poorly understood. This study examines whether and how O3 and PM2.5 may differentially impact mechanisms of cardiopulmonary pathophysiology. Methods: Exposures to each pollutant were manipulated for 89 office workers living together on a work campus in China with various combinations of an O3-generating electrostatic precipitator (ESP) and a high efficiency particulate air (HEPA) filter. Subjects were measured for biomarkers of cardiopulmonary pathophysiology at four time points each separated by 2-3 week intervals. Results: Mean 24-hour exposure concentrations during the study were 37 ± 1.5 µg/m3 for PM2.5 and 6.4 ± 0.2 ppb for O3, and they were significantly negatively correlated. Contrary to previous literature showing these biomarkers all being associated with PM2.5 exposure, this study shows that lung inflammation (fractional exhaled nitric oxide and exhaled breath condensate (EBC) nitrite and nitrate), systolic and diastolic blood pressure, and platelet activation (soluble P-selectin (sP-sel)) were tightly associated with short-term and chronic O3 exposure. In contrast, pulmonary oxidative stress (EBC malondialdehyde), arterial stiffness (augmentation index), and endothelial cell dysfunction (von Willebrand factor (VWF)) were significantly associated with chronic PM2.5 exposure. For example, an interquartile range (IQR) increase in 24-hour O3 exposure concentration (4.1 ppb) and 2-week mean ambient O3 (11.0 ppb) was significantly associated with a 12.5% and 27.4% increase in sP-sel, respectively. An IQR increase in 2-week mean ambient PM2.5 (41.4 µg/m3) was associated with a significant 11.2% increase in VWF. Conclusions: These findings have provided insights into biological mechanisms by which O3 and PM2.5 can differentially enhance cardiopulmonary disease risk.

Moderate drought did not affect the effectiveness of ethylenediurea (EDU) in protecting Populus cathayana from ambient ozone

A field study was conducted to evaluate the effects of ambient ozone (O3) on an O3-sensitive poplar (Populus cathayana) by using ethylenediurea (EDU) as a chemical protectant under two soil water treatments (well-watered (WW) and moderate drought (MD, 50–60% of WW in volumetric soil water content). EDU was applied as foliar spray at 0, 300, 450, and 600ppm. Photosynthetic parameters, pigment contents, leaf nitrogen, antioxidant capacity, growth, and biomass were measured. The 8h (9:00–17:00) average ambient O3 concentration was 71.7ppb, and AOT40 was 29.2ppmh during the experimental period (9 June to 21 September), which was high enough to cause plant injury. MD had significantly negative effects on P. cathayana, as indicated by reduced photosynthesis, growth, and biomass, and higher MDA contents. On the other hand, EDU significantly increased photosynthesis rate, chlorophyll a fluorescence, Vcmax and Jmax, photosynthetic pigments, total antioxidant capacity, tree growth and biomass accumulation, and reduced lipid peroxidation, but there was no significant interaction between EDU and drought for most parameters, indicating that EDU can efficiently protect Populus cathayana against ambient O3 and the protection was not affected by soil water contents when soil water reached moderate drought level. Among all doses, EDU at 450ppm provided maximum protection. Comparison of EDU-treated and non-treated P. cathayana could be used as a biomarker system in risk assessment of the effects of ambient O3 on forest health.

High doses of ethylene diurea (EDU) are not toxic to willow and act as nitrogen fertilizer

Ethylene diurea (EDU) is synthetic chemical which protects plants against damage caused by ground level O3 and is used experimentally as a biomonitoring tool at doses usually ranging from 200 to 400mgL−1 a.i. Although several studies have investigated the protective action of EDU, this mechanism remains unclear. Important uncertainties in EDU action are whether EDU acts as a source of nitrogen (N) to plants and whether high doses are phytotoxic. In order to answer these questions, we conducted an open-field experiment where potted willow (Salix sachalinensis Fr. Schm) plants were exposed to ambient O3 conditions and treated with 0, 800 or 1600mgL−1 EDU as a soil drench, every nine days, for about 2.5months. We examined approximately 50 response variables. Based on N content in different plant organs, we found that (a) all EDU was transferred to the leaves and (b) high doses of EDU increased the leaf N content. However, EDU did not affect the C content and distribution within the plant body. Still, even at the highest dose, EDU was not toxic to this fast-growing species (however such a high dose should not be applied in uncontrolled environments); and there was no EDU persistence in the soil, as indicated by soil N content. Notably, our soil was free from organic matter and N-poor.Key message: EDU per se does not cause toxicity to willow plants when applied as drench to a soil with no organic matter, rather, high EDU doses may act as nitrogen fertilizer in a nitrogen-poor soil.

Assessing ambient ozone injury in olive (Olea europaea L.) plants by using the antioxidant ethylenediurea (EDU) in Saudi Arabia.

The antiozonant chemical, ethylenediurea (N-[2-(2-oxo-1-imidazolidinyl)ethyl]-N'-phenylurea, abbreviated as EDU), was applied as stem injections or soil drenches to 5-year-old containerized plants of olive (Olea europaea L. cultivar Kalamata) in growth chambers in order to assess its ameliorative effects against realistic ozone (O3) stress. Visible injury symptoms were reduced greatly in individuals treated with EDU, with injection applications having greater protection than soil drenches. EDU application caused increases in the measured ecophysiological parameters compared to untreated individuals. In particular, the stem injection protected plants against photosynthetic impairment (unchanged net photosynthetic rates and intercellular CO2 concentration, in comparison to plants grown in filtered air). EDU application increased the protection of PSII from ambient O3 oxidative stress, although it did not retain the proportion of redox state of QA, pigment composition of photosynthetic apparatus and size of light-harvesting complex of PSII. However, the stem injection of plants with EDU induced lower non-photochemical quenching (NPQ) values in comparison to ambient air (-2%), indicating a better photoprotection of PSII in comparison to soil drench application. EDU application caused increases in the morphological and biometric parameters compared to individuals exposed to ambient air. To the best of our knowledge, this is the first study highlighting the protection of Kalamata olive trees due to EDU in terms of growth, yield, visible injury, and photosynthetic performance. Furthermore, this study proved that EDU could be a low-cost and a low-technology efficient tool for assessing O3 effects on plant performances in the field in Saudi Arabia.

Long-Term Ozone Exposure and Mortality in a Large Prospective Study

Tropospheric ozone (O3) is potentially associated with cardiovascular disease risk and premature death. Results from long-term epidemiological studies on O3 are scarce and inconclusive. In this study, we examined associations between chronic ambient O3 exposure and all-cause and cause-specific mortality in a large cohort of U.S. adults. Cancer Prevention Study II participants were enrolled in 1982. A total of 669,046 participants were analyzed, among whom 237,201 deaths occurred through 2004. We obtained estimates of O3 concentrations at the participant's residence from a hierarchical Bayesian space-time model. Estimates of fine particulate matter (particulate matter with an aerodynamic diameter of up to 2.5 μm [PM2.5]) and NO2 concentrations were obtained from land use regression. Cox proportional hazards regression models were used to examine mortality associations adjusted for individual- and ecological-level covariates. In single-pollutant models, we observed significant positive associations between O3, PM2.5, and NO2 concentrations and all-cause and cause-specific mortality. In two-pollutant models adjusted for PM2.5, significant positive associations remained between O3 and all-cause (hazard ratio [HR] per 10 ppb, 1.02; 95% confidence interval [CI], 1.01-1.04), circulatory (HR, 1.03; 95% CI, 1.01-1.05), and respiratory mortality (HR, 1.12; 95% CI, 1.08-1.16) that were unchanged with further adjustment for NO2. We also observed positive mortality associations with both PM2.5 (both near source and regional) and NO2 in multipollutant models. Findings derived from this large-scale prospective study suggest that long-term ambient O3 contributes to risk of respiratory and circulatory mortality. Substantial health and environmental benefits may be achieved by implementing further measures aimed at controlling O3 concentrations.

Limited effect of ozone reductions on the 20-year photosynthesis trend at Harvard forest.

Ozone (O3 ) damage to leaves can reduce plant photosynthesis, which suggests that declines in ambient O3 concentrations ([O3 ]) in the United States may have helped increase gross primary production (GPP) in recent decades. Here, we assess the effect of long-term changes in ambient [O3 ] using 20years of observations at Harvard forest. Using artificial neural networks, we found that the effect of the inclusion of [O3 ] as a predictor was slight, and independent of O3 concentrations, which suggests limited high-frequency O3 inhibition of GPP at this site. Simulations with a terrestrial biosphere model, however, suggest an average long-term O3 inhibition of 10.4% for 1992-2011. A decline of [O3 ] over the measurement period resulted in moderate predicted GPP trends of 0.02-0.04μmolCm-2 s-1 yr-1 , which is negligible relative to the total observed GPP trend of 0.41μmolCm-2 s-1 yr-1 . A similar conclusion is achieved with the widely used AOT40 metric. Combined, our results suggest that ozone reductions at Harvard forest are unlikely to have had a large impact on the photosynthesis trend over the past 20years. Such limited effects are mainly related to the slow responses of photosynthesis to changes in [O3 ]. Furthermore, we estimate that 40% of photosynthesis happens in the shade, where stomatal conductance and thus [O3 ] deposition is lower than for sunlit leaves. This portion of GPP remains unaffected by [O3 ], thus helping to buffer the changes of total photosynthesis due to varied [O3 ]. Our analyses suggest that current ozone reductions, although significant, cannot substantially alleviate the damages to forest ecosystems.

Temporal persistence of intra-urban spatial contrasts in ambient NO2, O3 and Ox in Edinburgh, UK

Ambient NO2, O3 and Ox (the sum of NO2 and O3) are associated with adverse health outcomes. Quantitative assessment of the health burden from these pollutants requires knowledge of small-scale variations in their concentrations in urban environments. In particular, we were interested in the temporal stability of intra-urban spatial contrasts in these pollutants. This was investigated by concurrent measurements of NO2 and O3 by passive samplers at 30 sites in Edinburgh, UK, repeated 12 × 1-weekly for NO2 and 6 × 2-weekly for O3 in summer and winter. Temporally persistent and large spatial variations in both NO2 and O3 concentrations were observed. Concentrations of NO2 across the sites ranged on average by a factor of 14 between suburban parks and heavily-trafficked roadsides, corresponding to a difference in NO2 on average of ∼80 μg m−3. Intra-urban O3 concentrations also varied substantially, on average by a factor of 4 (average range 45 μg m−3) and with strong anticorrelation to NO2 concentrations across the 30 sites. Consequently intra-urban variability was considerably lower for Ox than for NO2 and O3. The temporal stability in relative NO2 and O3 concentrations indicate potential for deriving intra-urban spatial fields of NO2 and O3 at different times by scaling models of long-term spatial patterns of NO2 and O3 by the measurements at a single site. If Ox is a key determinant of adverse health then the large intra-urban spatial contrasts in NO2 and O3 may be less relevant, with Ox concentrations across an urban area determined at a suitable background site.

Influence of post‐harvest crop residue fires on surface ozone mixing ratios in the N.W. IGP analyzed using 2 years of continuous in situ trace gas measurements

AbstractO3, CO, and NOx affect air quality and tropospheric chemistry but factors that control them in the densely populated N.W. Indo‐Gangetic Plain (IGP) are poorly understood. This work presents the first simultaneous 2 year long in situ data set acquired from August 2011 to September 2013 at a N.W. IGP site (30.667°N, 76.729°E; 310 m asl). We investigate the impact of emissions and meteorology on the diel and seasonal variability of O3, CO, and NOx. Regional post‐harvest crop residue fires contribute majorly to an enhancement of 19 ppb in hourly averaged ozone concentrations under similar meteorological conditions in summer and 7 ppb under conditions of lower radiation during the post monsoon. d[O3]/dt (from sunrise to daytime O3 maxima) was highest during periods influenced by post‐harvest fires in post monsoon season (9.2 ppb h−1) and lowest during monsoon season (4.1 ppb h−1). Analysis of air mass clusters revealed that enhanced chemical formation of O3 and not transport was the driver of the summertime and post monsoon ambient O3 maxima. Despite having high daytime NOx (&gt;12 ppb) and CO (&gt;440 ppb) in winter, average daytime O3 was less than 40 ppb due to reduced photochemistry and fog. Average daytime O3 during the monsoon was less than 45 ppb due to washout of precursors and suppressed photochemistry due to cloud cover. The 8 h ambient air quality O3 standard was violated on 451 days in the period August 2011–September 2013. The results show that substantial mitigation efforts are required to reduce regional O3 pollution in the N.W. IGP.

Ambient air pollution, weather changes, and outpatient visits for allergic conjunctivitis: A retrospective registry study.

Allergic conjunctivitis is a common problem that significantly impairs patients’ quality of life. Whether air pollution serves as a risk factor for the development of allergic conjunctivitis remains elusive. In this paper, we assess the relationship between air pollutants and weather conditions with outpatient visits for allergic conjunctivitis. By using a time-series analysis based on the largest dataset ever assembled to date, we found that the number of outpatient visits for allergic conjunctivitis was significantly correlated with the levels of NO2, O3, and temperature, while its association with humidity was statistically marginal. No associations between PM10, PM2.5, SO2, or wind velocity and outpatient visits were seen. Subgroup analyses showed that sex seemed to modify the effects of humidity on outpatient visits for allergic conjunctivitis, but not for NO2, O3, or temperature. People younger than 40 were found to be susceptible to changes of all four parameters, while those older than 40 were only consistently affected by NO2 levels. Our findings revealed that higher levels of ambient NO2, O3, and temperature increase the chances of outpatient visits for allergic conjunctivitis. Ambient air pollution and weather changes may contribute to the worsening of allergic conjunctivitis.

Effects of ambient gaseous pollutants on photosynthesis, growth, yield and grain quality of selected crops grown at different sites varying in pollution levels

ABSTRACTIn recent decades, ambient gaseous pollution has increased due to anthropogenic activities worldwide. The studies to evaluate the adverse effects of ambient pollutants on commonly grown food crops are still limited, especially in Asian countries like Pakistan. The present study was conducted to measure the ambient pollutants in different sites of Faisalabad and their impact on growth and yield of wheat, mung bean and peas. Plants were grown in pots and placed at three sites named as control (Wire house of Government College University, Faisalabad), low pollution (LP) (Farm Area of Ayub Agricultural Research Institute) and high pollution (HP) (GT Chowk, Faisalabad) sites. Results showed that ambient ozone (O3) concentration was highest at HP site followed by LP site and was below AOT40 in control site. Ambient pollutants caused foliar injury in crops and decreased plant height, leaf area, biomass and grain yield. Pollutants caused a reduction in photosynthetic pigments, stomatal conductance and net photosynthetic rate and grain protein contents in all three crops. In conclusion, the ambient O3 level was highest at HP site, this current O3 level and other pollutants decreased the growth and yield of important food crops.

Early and late adjustments of the photosynthetic traits and stomatal density in Quercus ilex L. grown in an ozone-enriched environment.

Quercus ilex L. seedlings were exposed in open-top chambers for one growing season to three levels of ozone (O3 ): charcoal filtered air, non-filtered air supplemented with +30% or +74% ambient air O3 . Key functional parameters related to photosynthetic performance and stomatal density were measured to evaluate the response mechanisms of Q. ilex to chronic O3 exposure, clarifying how ecophysiological traits are modulated during the season in an ozone-enriched environment. Dark respiration showed an early response to O3 exposure, increasing approximately 45% relative to charcoal-filtered air in both O3 enriched treatments. However, at the end of the growing season, maximum rate of assimilation (Amax ) and stomatal conductance (gs ) showed a decline (-13% and -36%, for Amax and gs , respectively) only in plants under higher O3 levels. Photosystem I functionality supported the capacity of Q. ilex to cope with oxidative stress by adjusting the energy flow partitioning inside the photosystems. The response to O3 was also characterised by increased stomatal density in both O3 enriched treatments relative to controls. Our results suggest that in order to improve the reliability of metrics for O3 risk assessment, the seasonal changes in the response of gs and photosynthetic machinery to O3 stress should be considered.

Metrics of ozone risk assessment for Southern European forests: Canopy moisture content as a potential plant response indicator

Present standards for protecting ecosystems from ozone (O3), such as AOT40, use atmospheric concentrations. A stomatal flux-based approach (Phytotoxic O3 Dose, PODY) has been suggested. We compared the spatial and temporal distribution of AOT40 and PODY – with and without a hourly threshold of uptake (POD1 and POD0) – for Pinus halepensis and Fagus sylvatica in South-eastern France and North-western Italy. Ozone uptake was simulated by including limitation due to soil water content, as this is an important parameter in water-limited environments. Both AOT40 and POD1 exceeded the critical levels suggested for forests. AOT40 suggested a larger O3 risk relative to PODY. No significant spatial and temporal difference occurred between POD1 and POD0. The use of POD0 in the assessment of ambient O3 risk for vegetation is thus recommended, because it is more biologically-meaningful than AOT40 and easier to be calculated than POD1. Canopy Moisture Content (CMC), a proxy of foliar water content, was modelled and tested as a potential plant O3 response indicator. CMC response to O3 was species-specific, and thus cannot be recommended in the epidemiology of O3 injury to forests.

Spatial and temporal trends of ozone distribution in the Jizerské hory Mountains of the Czech Republic.

We present results of the 5-year monitoring of ambient O3 concentrations in a Central European medium altitude mountain forested area. O3 levels were measured at 11 sites between 714 and 1000 m a.s.l. in 2006-2010 vegetation seasons using Ogawa diffusive samplers. Our results reveal that O3 exposure in the Jizerské hory Mts. was relatively high and comparable with polluted sites in Southern Europe and in higher altitudes. O3 concentrations differed significantly between individual sites and in individual years. O3 concentrations showed clear dependence on altitude at sites with similar aspect. Its gradient for the entire 5-year period under review equaled 3.5 ppb/100 m of altitude, ranging between nearly 5 ppb/100 m of altitude in 2006 and nearly 3 ppb/100 m of altitude in 2010. O3 concentrations at the site with northern aspect were consistently significantly lower than at the site at similar altitude with southern aspect. O3 concentrations measured at the forest edge were consistently lower than those measured at the same site but at the forest clearing. It is evident that the macro-setting of the O3 monitoring site is crucial for obtaining reliable results with high representativeness for the area.

Effects of Ambient Ozone Concentrations on Contents of Nonstructural Carbohydrates in Phoebe bournei and Pinus massoniana Seedlings in Subtropical China

Ground-level ozone (O3) pollution has affected carbon metabolism in tree species, which becomes one of the top environmental issues in China. In this paper, 1-year-old seedlings of Phoebe bournei and Pinus massoniana Lamb. were grown under field conditions at a rural site near the city of Taihe (Jiangxi Province). The plants were exposed in open-top chambers either to charcoal-filtered air or nonfiltered ambient air for 145 days. At the end of the growth season, the plants were harvested and the major nonstructural carbohydrates in leaves and roots were determined. Exposure to nonfiltered ambient air compared with filtered air controls caused an increase of sucrose, glucose, fructose, starch, and total nonstructural carbohydrates (TNCs) in fine roots of Ph. bournei, while there is no change in carbohydrate contents in Pi. massoniana roots. Compared with filtered air, in Ph. Bournei, starch and TNCs in leaves were reduced by 48 and 7 %, respectively, in ambient O3. While, ambient O3 just increased TNC content by 8.9 % in Pi. massoniana needles compared to filtered air. In summary, ambient O3 affected carbohydrate metabolism of these two subtropical tree species in China, and Pi. massoniana was less sensitive than Ph. bournei. O3 induced much greater changes in the amounts of carbohydrates in roots than in leaves.

Effects of long-term ambient ozone exposure on biomass and wood traits in poplar treated with ethylenediurea (EDU)

This is the longest continuous experiment where ethylenediurea (EDU) was used to protect plants from ozone (O3). Effects of long-term ambient O3 exposure (23 ppm h AOT40) on biomass of an O3 sensitive poplar clone (Oxford) were examined after six years from in-ground planting. Trees were irrigated with either water or 450 ppm EDU. Above (−51%) and below-ground biomass (−47%) was reduced by O3 although the effect was significant only for stem and coarse roots. Ambient O3 decreased diameter of the lower stem, and increased moisture content along the stem of not-protected plants (+16%). No other change in the physical wood structure was observed. A comparison with a previous assessment in the same experiment suggested that O3 effects on biomass partitioning to above-ground organs depend on the tree ontogenetic stage. The root/shoot ratios did not change, suggesting that previous short-term observations of reduced allocation to tree roots may be overestimated.

Association between Chronic Laryngitis and Particulate Matter Based on the Korea National Health and Nutrition Examination Survey 2008-2012.

BackgroundChronic laryngitis (CL) has been described as chronic inflammation of the larynx. CL have various causes such as long-term smoking, acid reflux, voice overuse, bronchitis, allergies, pneumonia, excessive exposure to toxic chemicals and complications from the flu or a chronic cold. However, the prevalence of CL and role of air pollution in the etiology is uncertain.ObjectiveThe aim of this study was to investigate the relationship between CL and particulate matter with aerodynamic diameter less than 10 μm (PM10) in South Korea using data from the Korea National Health and Nutrition Examination Surveys (KNHANES) during 2008–2012.MethodsKNHANES is a cross-sectional survey of the civilian, non-institutionalized population of South Korea (n = 21,116). A field survey team that included an otolaryngologist moved with a mobile examination unit and performed interviews and physical examinations. The mean annual concentrations of ambient PM10, SO2, O3, NO2, and CO levels in Korea were determined from monitoring station data. Multiple logistic regression was used to examine the relationship of air pollution to CL.ResultsAmong the population ≥ 19 years of age, the weighted prevalence of CL was 3.37 ± 0.30% (95% confidence interval, 2.79–3.95%). CL was more prevalent in men, current smokers, and those with lower household income and prevalence increased with age. A significant decrease over time was observed in the prevalence of CL (P for trend = 0.0049) and the annual average concentrations of PM10 (P for trend < 0.0001) from 2008 to 2012. In a multivariate model, the factors associated with CL included PM10 (odds ratio [OR], 1.378, p = 0.0457), age (OR, 1.020, p<0.0001), sex (OR, 0.734, p = 0.0179), and smoking status (OR, 1.438, p = 0.0054).ConclusionElevated PM10 exposures could be associated with increased risk of CL in South Koreans. Further epidemiological and experimental studies are necessary to clarify the impact of chronic PM10 exposure on CL.