Annual O3 Concentrations Research Articles

Association between long-term exposure to ambient ozone and sperm quality in Shandong Province

Objective: To evaluate the association between long-term exposure to ambient ozone (O3) and sperm quality. Methods: From January 1, 2014, to December 31, 2019, healthy sperm donors were recruited through the Human Sperm Bank of Shandong University Affiliated Reproductive Hospital. A total of 37 977 sperm donation data from 2 971 healthy volunteers were analyzed. The average annual O3 concentration (0.01°× 0.01°) was matched according to household address. A multivariate mixed-effect model was used to analyze the exposure-response relationship between the average O3 exposure concentration and sperm quality in the previous year, with each donor as a random intercept. All results were presented as % changes with 95% confidence intervals (CIs) for all sperm parameters associated with 10 μg/m3 increases in O3. The effects of individual characteristics on the association between O3 and sperm quality were evaluated by stratified analysis. Results: The average O3 concentration in the year before semen collection was (107.09±7.50) μg/m3. Each 10 μg/m3 increase in O3 was associated with declined sperm concentration (-3.12%, 95%CI:-4.55%, -1.67%), total sperm count (-5.21%, 95%CI:-7.28%, -3.09%), total sperm motility (-1.49%, 95%CI:-2.37%, -0.61%), progressive motility (-2.53%, 95%CI:-3.78%, -1.26%), total motile sperm count (-5.82%, 95%CI:-8.17%, -3.41%), and progressively motile sperm count (-6.22%, 95%CI:-8.73%, -3.64%). Men aged 30 and above, obese, and with lower education levels might be more susceptible to the influence of O3 on sperm quality, but the difference was not statistically significant (P>0.05). Conclusion: Long-term exposure to O3 in Shandong Province is associated with a decrease in sperm quality.

A multiscale geographically weighted regression kriging method for spatial downscaling of satellite-based ozone datasets

Accurate monitoring of ozone (O3) concentrations by remote sensing is essential for achieving pollution control and ecological protection. However, the existing O3 remote sensing data with a low spatial resolution do not facilitate fine-grained studies of small-scale urban clusters. In this study, the multiscale geographically weighted regression kriging (MGWRK) method was used to spatially downscale O3 remote sensing products (10 km × 10 km). Downscaling factors were selected from meteorological factors and vegetation, aerosol optical thickness (AOD), and air pollutant emission inventory data. Spatial heterogeneity and scale differences among the factors were considered and compared via multiple regression kriging (MLRK) and geographically weighted regression kriging (GWRK) to generate 1-km annual and seasonal O3 remote sensing products. The results showed that I) the downscaling accuracy of each model can be expressed as MGWRK > GWRK > MLRK; the local downscaling model yields data that are more consistent with the actual spatial distribution of O3 after considering the spatial heterogeneity of the influencing factors; and the downscaled annual and seasonal data exhibit satisfactory spatial texture characteristics and consistency with the original spatial distribution of O3, while the distribution boundary problem of image elements is eliminated. II) Nitrogen oxide (NOx) and volatile organic compound emissions and temperature exhibit strong positive correlations with O3, while wind speed, humidity, the normalized difference vegetation index, and AOD indicate weak positive correlations with O3. Moreover, precipitation exhibits a weak negative correlation with O3. III) The coefficient of determination (R2) of the 1-km resolution annual O3 concentration data after downscaling based on the MGWRK model reaches 0.93, while the RRMSE and MAE values are only 3% and 1.86, respectively, with a coefficient of variation of 9.55%; the downscaling accuracy of the seasonal O3 concentration data is higher in summer and winter than during the other seasons, with R2 greater than 0.85, further confirming the spatial and temporal downscaling advantages of the MGWRK model for O3 in the Chang-Zhu-Tan city cluster. This further corroborates the feasibility of the MGWRK model for spatial and temporal O3 downscaling in the Chang-Zhu-Tan urban area.

Distribution and Long-Term Trends of Tropospheric Ozone Concentrations in Ireland

Tropospheric ozone (O3) is highly variable over space and time reflecting local production and destruction as well as addition and loss through regional and long-range transport. In this study, O3 concentrations at 11 stations in Ireland and their long-term trends (7–9 sites) were evaluated; O3 concentrations (2015–2019) varied spatially, with the highest annual mean concentrations along the Atlantic west coast (69–75 µg/m3), and the lowest in urban centres (39–43 µg/m3). Ozone followed a seasonal pattern of spring and winter maximum and summer–autumn minimum. Significant long-term (2005–2019) increases were observed in annual O3 concentration at two rural stations, while increases were larger and more frequent during winter with increases at four out of seven stations. During the decade 2010–2019, significant annual increases were observed at four out of nine stations. Observed site- and season-specific increasing trends in O3 concentrations likely reflected changes in regional precursor gas emissions sources. Despite reported decreases in background concentrations in the marine boundary layer in northern mid-latitudes in recent decades, O3 concentrations at some sites in Ireland have increased significantly primarily driven by changes in winter concentrations. There were no significant decreasing trends at any site or in any season.

Urban Surface Ozone Concentration in Mainland China during 2015-2020: Spatial Clustering and Temporal Dynamics.

Urban ozone (O3) pollution in the atmosphere has become increasingly prominent on a national scale in mainland China, although the atmospheric particulate matter pollution has been significantly reduced in recent years. The clustering and dynamic variation characteristics of the O3 concentrations in cities across the country, however, have not been accurately explored at relevant spatiotemporal scales. In this study, a standard deviational ellipse analysis and multiscale geographically weighted regression models were applied to explore the migration process and influencing factors of O3 pollution based on measured data from urban monitoring sites in mainland China. The results suggested that the urban O3 concentration in mainland China reached its peak in 2018, and the annual O3 concentration reached 157 ± 27 μg/m3 from 2015 to 2020. On the scale of the whole Chinese mainland, the distribution of O3 exhibited spatial dependence and aggregation. On the regional scale, the areas of high O3 concentrations were mainly concentrated in Beijing-Tianjin-Hebei, Shandong, Jiangsu, Henan, and other regions. In addition, the standard deviation ellipse of the urban O3 concentration covered the entire eastern part of mainland China. Overall, the geographic center of ozone pollution has a tendency to move to the south with the time variation. The interaction between sunshine hours and other factors (precipitation, NO2, DEM, SO2, PM2.5) significantly affected the variation of urban O3 concentration. In Southwest China, Northwest China, and Central China, the suppression effect of vegetation on local O3 was more obvious than that in other regions. Therefore, this study clarified for the first time the migration path of the gravity center of the urban O3 pollution and identified the key areas for the prevention and control of O3 pollution in mainland China.

Long-term characteristics of criteria air pollutants in megacities of Harbin-Changchun megalopolis, Northeast China: Spatiotemporal variations, source analysis, and meteorological effects

The hourly concentration of six criteria air pollutants in the Harbin-Changchun region were used to investigate the status and spatiotemporal variation of target air pollutants and their relationships with meteorological factors. The annual concentrations of particulate matters during 2013–2017 were two times higher than the Chinese Ambient Air Quality Standards (CAAQS) Grade Ⅱ. The annual O3 concentration increased by two times during 2013–2018 in Harbin. The concentration of PM, SO2, NO2, and CO depicted a similar seasonal trend with an order of winter > autumn > spring > summer. The consistent interannual variation trends of PM2.5/CO, NO2 and SO2 indicated that the formation of secondary inorganic aerosols in the annual scale was dominated by the concentrations of NO2 and SO2. The interannual variations of the individual meteorological factors causing on PM2.5 and O3 during 2013–2018 varied significantly in seasonal scale. The interannual variations were stable in annual scale indicating that the continuous decline of PM2.5 during 2014–2018 can be attributed to the comprehensive and strict prohibition of small coal-fired boilers and straw burning in the study area. Meanwhile, the increase in O3 during 2013–2018 in the study area were mainly attributed to the rapid growth of the emission of its precursor (VOCs and NOx). The influence of meteorology on PM2.5 and ozone were the most stable and strongest in winter than that in the other three seasons.

Increasing surface ozone and enhanced secondary organic carbon formation at a city junction site: An epitome of the Yangtze River Delta, China (2014–2017)

This study aims to understand the characteristics of surface ozone (O3), search for factors affecting the variations in its concentration, and estimate its impacts on the secondary organic carbon (SOC) levels and atmospheric oxidation capacities in the Yangtze River Delta (YRD). Four years of continuous observations (2014–2017) of the surface O3, organic carbon, elemental carbon, nitrogen oxides, PM2.5 and meteorological factors along with three years of measurements (2015–2017) of the concentrations of 56 volatile organic compounds were conducted at a rural site. Our measurements showed that the total number of O3 pollution days more than doubled over the four-year period, from 28 days in 2014 to 76 days in 2017. The annual mean of the maximum daily 8-h average O3 concentration during the months with the strongest solar radiation (July–September) showed a 6.8% growth rate, from 124.5 (2014) to 149.8 μg m−3 (2017). Regional transport was shown to be the dominant contributor to the high level of O3 based on a process analysis of the O3 variation using the Weather Research and Forecasting-Community Multiscale Air Quality model for this site. The simulation results indicated that the city junction site served well as an epitome of the regional background of the YRD. We also found that the level of SOC, which is a major component of PM2.5 that results from atmospheric oxidizing processes, gradually increased with the increase in the surface O3 level, even though the overall PM2.5 concentration significantly decreased each year. There was an increasingly strong correlation between SOC and Ox (O3 + nitrogen dioxide) during both the daytime and night-time from 2014 to 2017 when the highest annual O3 concentration was observed. These findings imply that the atmospheric oxidation capacity increased and likely contributed to the SOC production in the YRD during 2014–2017.

Urban ozone sink inferred from surface measurements in China

This study detected the spatial variations in the surface O3 concentrations along the urban-suburban-rural-background land use gradient and strived to identify the driving factors of these spatial differences. The average O3 concentrations exhibited an increasing gradient from urban cores to background areas with values of 43.5 μg/m3 in urban areas, 50.1 μg/m3 in the green regions of urban areas, 50.6 μg/m3 in suburban towns, 53.9 μg/m3 in rural areas, and 69.1 μg/m3 at background sites. The differences in the annual O3 concentrations between urban and background areas were strongly negatively correlated with the differences in NO2 and PM10 (particulate matter 10 μm or less in diameter) across China. Moreover, the monthly O3 differences between urban and background sites were generally large when the O3 concentration at the background site was at a high level. At the hourly scale, the O3 differences were larger during the night than during the day, and the O3 differences were significantly negatively correlated with the differences in the NO2 and PM10 concentrations but positively correlated with those in the CO and SO2 concentrations. In particular, SO2 had a positive effect on the O3 concentration when SO2 was at a high level. These results provide a scientific basis for enacting policies to control O3 pollution.

Temporal variations and trend of ground-level ozone based on long-term measurements in Windsor, Canada

Abstract. This study investigates temporal variations and long-term (1996–2015) trends of ground-level O3 (ozone) and its precursors, NOx (nitrogen oxides), and volatile organic compounds in Windsor, Ontario, Canada. During the 20-year study period, NOx, non-methane hydrocarbon concentrations, and ozone formation potential decreased significantly by 58 %, 61 %, and 73 %, respectively, while O3 concentrations increased by 33 % (20.3 ppb in 1996 vs. 27 ppb in 2015). Our analysis revealed that the increased annual O3 concentrations in Windsor were due to (1) decreased O3 titration (by 50 % between 1996 and 2015) owing to declining nitric oxide concentrations, which is suggested by a slightly decreasing trend of annual mean total O3 concentrations after the titration effect is removed, (2) reduced local photochemical production of O3 because of dwindling precursor emissions, and (3) an increased background O3 level that has a greater impact on the low-to-median concentrations. The net effect of those factors is decreasing peak O3 levels during the smog season from May to September but an overall increasing trend of annual means. These results indicate that the emission control measures are effective in reducing peak ozone concentrations. However, challenges in lowering annual O3 levels call for long-term collaborative efforts in the region and around the globe.

Characteristics of Major Air Pollutants in China.

Following the rapid development of China's economy, air pollution has become more and more serious. Air pollution in China presents complex pollution characterized by high PM2.5 and O3 concentration. This study presents an overview of the status of air quality and emission in China and discusses the temporal and spatial distribution of major pollutants (PM10, PM2.5, SO2, NOX, and O3). The results show that the reduced emissions have improved the air quality in China. However, the Chinese National Ambient Air Quality Standard (CNAAQS) for PM10 and PM2.5 still be exceeded in many cities of China in 2015. A total of 77.5% (for PM2.5) and 65.4% (for PM10) of the monitoring cities were found to be exceeded CNAAQS. The average annual O3 concentration was increasing during 2013-2015, and 16% of the total cities in 2015 did not meet the CNAAQS, indicating that O3 pollution should be paid more attention. For NO2 and SO2, the exceedances of CNAAQS are rare. PM2.5, PM10, and SO2 concentrations are higher in northern than in southern regions. High NO2 occurred in Beijing-Tianjin-Hebei and Yangtze River delta region. Secondary particles formation and motor vehicle exhaust were the main sources of PM2.5 in megacities. Dust was the main source for PM10. The formation of O3 is VOC-limited in urban areas of China and NOX-limited in nonurban areas.

Long-term exposure to ambient ozone and mortality: a quantitative systematic review and meta-analysis of evidence from cohort studies

ObjectivesWhile there is good evidence for associations between short-term exposure to ozone and a range of adverse health outcomes, the evidence from narrative reviews for long-term exposure is suggestive of...

The EU-25 Emissions from Road Transport and Ground Level Ozone Air Pollution at Rural Mountain Sites in Slovakia~!2008-03-31~!2008-09-25~!2008-11-28~!

Road transport sector produces a significant quantity of ground level ozone (O3) precursors. Relevant abatement of exhaust emissions has been achieved in Europe during last decades due to environmental policy. Presented results indicate relatively weak response of key O3 precursors decrease: NOx (-40%), NMVOC (-69%), and CO (-63%) from the EU-25 road transport to O3 concentration at background site Stará Lesná in Slovakia for time period 1992-2005. At this site mean annual O3 concentration varies around 63.4 μg m-3 and detected slight decrease of -0.89 μg m-3/decade is not statistically significant. Furthermore, high O3 concentrations occurred in the High Tatra Mts region during the August 2003 heat wave which showed an important impact of long-range air pollution on air quality of Slovak mountain region. More studies will be needed to specify the role of meteorological and environmental factors in the transport and transformation of emissions from large urban regions to remote sites.