Search

The Houston-Galveston-Brazoria (HGB) area of Texas has historically experienced severe air pollution events with high concentrations of ozone (O3) during the summer season. This study evaluates the contribution of different anthropogenic sources to ozone formation in the HGB area. The Emission Processing System (EPS3) is used to process emission files in four different scenarios (Base case as including All emission sources (BC), All sources— Area sources (AMA), All sources—Point sources (AMP), and All sources— Mobile sources (AMM). These files are used as input in photochemical modeling with the Comprehensive Air Quality Model with Extensions (CAMx) to simulate ozone formation. The data is analyzed for daily maximum ozone concentrations and contribution of source categories at three air quality monitoring locations (La Porte Sylvan beach-C556, Houston Texas avenue-C411, and Texas city in Galveston-C683) for a study period of June 1-June 30, 2012. The contribution of the point sources to ozone formation is dominated at all three locations, followed by mobile sources and area sources on high ozone days. The relative contributions of point sources are 27.51% ± 3.53%, 21.45% ± 7.36%, and 30.30% ± 9.36%; and mobile sources are 18.27% ± 2.22%, 20.60% ± 6.89%, and 18.61% ± 7.43%; and area sources were 4.2% ± 1.65%, 5.21% ± 1.59%, and 3.72% ± 1.52% at C556, C411, and C683, respectively. These results demonstrate the importance of regulatory focus on controlling point and mobile source emissions for NAAQS attainment in the study region.

Ozone, a major contributor to poor air quality, has an array of adverse effects on human, animal, and plant health. In the Los Angeles basin, a megacity that has pursued cleaner air for decades, unhealthy levels of ozone have decreased but remain stubbornly frequent even as the ozone precursors NOx (nitrogen oxides ≡ NO2 + NO) and VOC (volatile organic compounds) have decreased. We describe a combined analysis of decadal trends in these precursors, differences in emissions with day-of-week, and of the impact of temperature to assess the role of VOC and NOx and the likely effects of additional emission reductions on the occurrence of high ozone in the region.

This paper deals with ground-level ozone classification in the El Paso-Juarez area using statistical data mining algorithms. The persistence of highly concentrated ozone levels in the troposphere does harm to humans, animals, and plants. So, early detection of high ozone levels is essential to ensure a healthy environment, especially for the elderly, the children, and the asthma patients. For this study, we have used the data sets of air pollutants and meteorological variables from 2015 to 2019 from the El Paso area, which frequently exceeds the National Ambient Air Quality Standard. Five supervised machine learning techniques are studied to classify the likelihood of high/low ozone days in the atmosphere with great accuracy. These techniques help to obtain primary variables that cause high ozone concentration. We predicted the data based on the key variables and computed the prediction accuracy using several evaluation metrics. The results suggest that supervised machine learning techniques are useful in classifying high/low ozone days in this area.

The adoption of ozonation for water disinfection is hindered by its high ozone demand and the resulting high cost. Electric field treatment inactivates bacteria by physically disrupting the integrity of the cell membrane. Assisted by nanowire-modified electrodes, locally enhanced electric field treatment (LEEFT) reduces the required voltage to several volts to induce sufficient electric field strength for efficient bacteria inactivation. In this study, the LEEFT is applied as a pretreatment of ozonation for bacteria inactivation. Our results show that a low-voltage (0.4 V) LEEFT has no obvious effect on the following ozonation, but a higher-voltage (0.6-1.2 V) LEEFT significantly enhances the ozone inactivation. After the LEEFT, a large number of viable cells with impaired cell membranes are observed, shown by both selective plate count and staining methods. The mechanism inducing the enhancement is explained by the initially reparable pores generated by LEEFT that cannot recover in the subsequent ozonation and the greater intracellular diffusion of ozone after the membrane disruption induced by LEEFT. The application of LEEFT as a pretreatment process is beneficial to reduce the ozone dosage and disinfection by-product formation with a broader inactivation spectrum, which facilitates the application of ozonation in primary water disinfection.

Objectives: The present study was focused on the 8-hour average concentration of ground-level ozone in the city of Visakhapatnam for three years in a row, i.e. 2017, 2018, and 2019, and the effects of ozone on human life, the environment, and building materials. Method: The data of 8-Hour average groundlevel ozone concentration was collected for the study from the Central Control Room for Air Quality Management – All India, Central Pollution Control Board. Data available from the source were analyzed and compared to the NAAQS, India and the data was tabulated and showed specifically the number of times the 8 Hour average ground-level ozone surpassed in a month, for a clearer understanding. Findings: Study results show that the air quality of ozone levels during winters showed maximum unhealthy hours. The trends of maximum recorded 8-Hour average concentration of ozone levels in a day are also increasing year by year. Recommendations: It is recommended to be safe indoors during high ozone days for the people with comorbidities, children, Women in pregnant, people active in outdoor activities and it is further advised to reduce ozone exposure it\'s safe to wear washable 6-layer N99 and PM2.5 face mask during winters especially from November to February. Schools may be cautioned to discontinue the open-air physical activity during this period.Creating ozone forecasts accessible to the public is important, and the local and national laws should be strengthened to combat ozone pollution. Keywords: Asthma; contamination; ecosystems; urban vegetation; ozone; mortality

Volatile organic compounds (VOCs) and nitrogen oxides (NOx) play a key role in tropospheric chemistry. A typical urban scenario, under VOC-controlled conditions (low VOC/NOx ratios), is discussed with emphasis on the kinetic conditions leading to high ozone concentrations for an urban area of Brazil. As a base case, kinetic and mechanistic reactivities of individual VOCs, were evaluated in the district of Iraja (Rio de Janeiro, Brazil), which receives air masses originating from an industrial area. Aromatic compounds contributed with 41.1% of total mass. They were the most reactive species, representing 48.8% of the total kinetic reactivity and 71.0, 61.0 and 55.9% of the mechanistic reactivity, in MIR, MOIR and EBIR scales, respectively. Results showed that high ozone concentrations are due to a combination of conditions, mainly, relatively low NOx levels and a relatively high reactive VOC mix, primarily originating from an industrial area. Average ozone forming potential for the samples were calculated as 3.57, 1.39 and 0.74 for the MIR, MOIR and EBIR scales, respectively.

Although precursor concentrations were reduced by emission control in Guangzhou, southern China from 2006 to 2016, ground-level O3 concentrations increased, forming potential risks to human health. This study explored the impacts of large-scale synoptic weather circulations on O3 concentration in Guangzhou, in a particular focus on high O3 pollution episodes. Twelve local weather types were clustered based on Lamb-Jenkinson weather types (LWTs). Analyses showed that LWTs strongly impacted daily O3 concentrations: A, AS, CN, and N+ weather types were likely associated with high ozone concentrations, while the ozone levels were relatively low under C, CE, CS, and S+ types. LWTs could explain 30–40% of the inter-annual variability of O3 concentration during the dry season. Numerical model simulations further demonstrated that continuous type A weather was the leading LWT correlated with high O3 concentrations, while type C weather was the predominant type correlated with low O3 concentrations. CMIP5 model results showed that occurrences of weather type A would increase by about 25% in the high emission scenario over the 2020–2069 period, which might worsen the O3 pollution in Guangzhou in the future. The increase in frequency weather type A would not be significant under the low emission scenario during the same period. Therefore, we should strictly implement the global emission reduction plan to prevent the change of weather circulation caused by climate change from aggravating ozone pollution in the future. The strong link between O3 concentrations and LWT frequencies makes the daily occurrence of LWTs a useful predictor for episodes of high O3 pollution and makes annual frequencies of LWTs good indicators of the inter-annual variability of the O3 concentration. These results are useful in efforts to predict O3 concentrations, providing a reliable weather forecast is available.

Daytime onshore lake breezes are a critical factor controlling ozone abundance at coastal sites around Lake Michigan. Coastal counties along the western shore of Lake Michigan have historically observed high ozone episodes dating to the 1970s. We classified ozone episode days based on the extent or absence of the lake breeze (i.e., “inland”, “near-shore” or “no” lake breeze) to establish a climatology of these events. This work demonstrated variable gradients in ozone abundances based on these different types of meteorology, with the sharpest ozone concentration gradients on days with a near-shore lake breeze. On 76–82% of days in which ozone reached 70 ppb for at least 1 h, a lake breeze was present. Evidence of ozone gradients from multiple observation platforms during the 2017 Lake Michigan Ozone Study (LMOS 2017) are shown for two days with different depths of lake breezes.

The meso-scale meteorology of lake breezes along Lake Michigan impacts local observations of high ozone events. Previous manned aircraft and UAS observations have demonstrated non-uniform ozone concentrations within and above the marine layer over water and within shoreline environments. During the 2021 Wisconsin’s Dynamic Influence of Shoreline Circulations on Ozone (WiscoDISCO-21) campaign, two UAS platforms, a fixed-wing (University of Colorado RAAVEN) and a multirotor (Purdue University DJI M210), were used simultaneously to capture lake breeze during forecasted high ozone events at Chiwaukee Prairie State Natural Area in southeastern Wisconsin from May 21–26, 2021. The RAAVEN platform (data DOI: 10.5281/zenodo.5142491) measured temperature, humidity, and 3-D winds during 2-hour flights following two separate flight patterns up to 3 times per day at altitudes reaching 500 m above ground level. The M210 platform (data DOI: 10.5281/zenodo.5160346) measured vertical profiles of temperature, humidity and ozone during 15-minute flights up to 6 times per day at altitudes reaching 120 m above ground level (AGL) near to a WI-DNR ground monitoring station (AIRS ID: 55-059-0019). This campaign was conducted in conjunction with the Enhanced Ozone Monitoring plan from WI-DNR that included Doppler lidar wind profiler observations at the site (data DOI:10.5281/zenodo.5213039).

High-intensity emission controls were implemented in Nanjing and in 8 surrounding cities to ensure good air quality during the 2014 summer Youth Olympic Games (YOG). An Aerodyne soot-particle aerosol mass spectrometer (SP-AMS) was deployed at a downwind site of downtown Nanjing to investigate the chemical composition, sources, and size distribution of submicron aerosols (PM1), in response to emission control policies. However, results show that emission controls played a negligible role in reducing PM1 concentration during the YOG period, yet primary precursors such as NOx and SO2 were decreased by 10–20%. Low wind speed, high relative humidity, and high ozone (O3) concentration likely play a significant role in the production and accumulation of the oxygenated organic aerosol (OOA) and the secondary inorganic aerosols (SIA) in summer Nanjing. We propose that long-term regional emission reduction could be a solution for future air pollution mitigation strategies in downwind cities of the YRD region, and that seasonal meteorological characteristics in a specific region should be considered before emission control policies are made.

Efforts to stem the transmission of coronavirus disease 2019 (COVID-19) led to rapid, global ancillary reductions in air pollutant emissions. Here, we quantify the impact on tropospheric ozone using a multiconstituent chemical data assimilation system. Anthropogenic NOGlobal Tropospheric Ozone Responses to Reduced Noₓ Emissions Linked to the COVID-19 Worldwide Lockdowns emissions dropped by at least 15% globally and 18 to 25% regionally in April and May 2020, which decreased free tropospheric ozone by up to 5 parts per billion, consistent with independent satellite observations. The global total tropospheric ozone burden declined by 6TgO₃ (∼2%) in May and June 2020, largely due to emission reductions in Asia and the Americas that were amplified by regionally high ozone production efficiencies (up to 4 TgO₃/TgN). Our results show that COVID-19 mitigation left a global atmospheric imprint that altered atmospheric oxidative capacity and climate radiative forcing, providing a test of the efficacy of NOₓ emissions controls for co-benefiting air quality and climate.

The trends per 5th percentile interval of European surface ozone concentrations over urban, suburban and rural sites in the period 1995–2012 have been estimated based on observational data from the European Environment Agency air quality database. Consistent with previous study results, we find a rapid decline of relatively high ozone concentrations after the year 1995, especially of rural summertime ozone. However, the decreasing rate has slowed, and even reversed, of low-level ozone, especially in the urban environment for all seasons. Although the ozone air pollution problem has been declared to be effectively resolved by achieving European air quality goals, our results indicate that ozone remains to be difficult to control for a long time into the future. Global and regional models poorly reproduce the measured differences in ozone and trends in different levels and regions. Thus policy guidelines from the model should be considered with care.

Ozone was investigated as a potential alternative to control phosphine resistant strains of the lesser grain borer, Rhyzopertha dominica (F.). The efficacy of 0.21 and 0.42 g/m3 concentrations of ozone against one phosphine-susceptible laboratory and two phosphine-resistant field strains of R. dominica was evaluated. Vials holding 20 adults with 0 and 10 g of wheat were exposed to each ozone concentration for up to 24 h to estimate lethal doses required for 50 (LD50) and 99% (LD99) mortality. After ozone exposure, mortality was assessed 5 d later. There were no significant differences between LD50 values of the samples exposed to 0.21 and 0.42 g/m3, regardless of strains and presence or absence of wheat. The small amount of wheat (10 g) affected efficacy at 0.21 g/m3, but showed a non-significant effect at 0.42 g/m3. Ozone tends to react with active sites on the surface of wheat kernels prior to reaching an effective lethal concentration for insects. High ozone concentration in the supply air reduced the time to saturate all active sites and ensured that lethal levels of free ozone were available to kill insects. Ozone successfully suppressed the adult progeny production for all tested strains. Emergence of adults from eggs of all three strains was reduced by 96.3–100% only after 72 h exposure to an ozone concentration of 0.42 g/m3. At the same ozone concentration, emergence of adults from young and old larvae was reduced by 97.1–99.7% after a 24 to 34 h exposure. However, reduction in emergence of adults from ozone exposed pupae at 10 h varied among the strains and ranged from 32.8 to 96.6%. After 2 and 6 h of exposure the reduction in emergence of adults from pupae ranged from 19.6 to 76.5%.

Climate warming may bear a penalty on future ozone air quality, even in the absence of changes in anthropogenic activities. This penalty has important implications for policy-making, but its quantification involves complex meteorological, chemical, and biological processes and feedbacks that are not well understood. We examined how climate-sensitive processes may affect surface ozone, identified key knowledge gaps uncovered by recent studies, and summarized latest assessments of the climate change penalty on ozone air quality. Recent analyses have challenged earlier paradigms on how climate change may affect surface ozone. The widely accepted associations of high ozone events with stagnation and heat waves require re-examination. Emission responses of natural precursors to climate warming may be significantly modulated by CO2 levels and ecosystem feedbacks, such that the direction of emission changes cannot be robustly determined at this time. Climate variability may drive fluctuations in surface ozone, which has implications for near-term air quality management. Recent studies have generally projected a climate change penalty on ozone air quality, although the magnitudes are smaller than those projected by earlier studies. This review examined the latest understanding on the climate change penalty to surface ozone. Critical uncertainties are associated with the meteorological, chemical, and biological processes linking climate warming and ozone, and many of the known feedbacks are not yet included in models. Further research is needed to examine those processes in order to better quantify the climate change penalty on surface ozone to inform policy-making.

Ozone and low temperatures influence on isolation of electrical materials are considered. Combination of low temperature food storage with the electron-ion technology (including ozone) gives an ability to solve the problems of products spoilage minimization and reduction of energy consumption. Real objects have storage temperatures from -24°C till +24°С. Ozone is used at the same. Power, electrical and informational communication lines were used. The object of the research was samples of electrical products. Usually they are used in low temperature storage chambers. Combined effect of low temperatures, ozone different densities, mechanical loading on isolation of communicational lines are analyzed. Most samples after exposure of low temperatures and high ozone densities stand the test. That’s why it is possible to use them in practice. Only KG (H07RN-F) didn’t pass the test. The isolation of several samples, such as VVG (NYY-O), VVGng (NYY-J), PWC (H05VV-F) and PW-3, cracked at cooling temperatures -18°С and -24°С. In real use these samples are not so loaded. So, it can be considered, that in conditions of long use, electrical materials are usable (low temperatures and ozone densities till 40 g/m 3 are allowed). The results allow making a conclusion that most modern industrial low temperature storage chambers let use electron-ion technologies.

Using data from the St. Luke's site in Meridian, ID (near Boise) during 2006–2017 and a 2017 summer intensive campaign, we investigate enhancements in ozone (O3) during wildfire events in an urban area. We calculate a wildfire criterion based on the National Oceanic and Atmospheric Administration (NOAA) National Environmental Satellite, Data, and Information Service (NESDIS) Hazard Mapping System (HMS) smoke product and historically averaged PM2.5 data to determine when wildfire emissions are influencing the area (smoke vs. non-smoke events). We also use a Generalized Additive Model (GAM) to investigate anomalous sources of O3, such as wildfires, in this urban area. During the summer 2017 intensive campaign, we find that peroxyacetyl nitrate (PAN), reactive nitrogen (NOy), and maximum daily 8 h average (MDA8) O3 show significant enhancements during smoke events compared with non-smoke periods (65%, 42%, and 32%, respectively). We calculate the 95% confidence interval of ΔPM2.5/ΔCO, ΔNOy/ΔCO, ΔPAN/ΔNOy, and ΔPAN/ΔCO enhancement ratios (ERs) to be 0.129–0.144 μg/m3/ppbv, 0.018–0.022 ppbv/ppbv, 0.152–0.192 ppbv/ppbv, and 3.04–3.76 ppbv/ppmv, respectively, for wildfire smoke influenced events. We also observe an enhancement in O3 production up to PM2.5 concentrations of 60–70 μg/m3 in smoke, after which we see a reduction in average MDA8 O3 mixing ratios. We use the four highest O3 events during summer 2017 as case studies to examine the highly variable conditions due to the influence of wildfire smoke in an urban area. In two cases, we investigate smoke days that show significant O3 enhancement and moderate PM2.5 concentrations. These cases suggest that ERs, such as ΔPM2.5/ΔCO and ΔNOy/ΔCO, are less useful in determining the influence of wildfire smoke in an urban area on moderate smoke days. Another case shows reduced O3 production during a very high, 3-day smoke event (PM2.5 > 70 μg/m3). After this high smoke period, a 20 ppbv enhancement in MDA8 O3 is observed in moderate smoke. These results indicate that wildfire-influenced O3 enhancements are highly variable in urban areas but generally increase up to around 60 μg/m3 of PM2.5, after which they decrease at very high smoke concentrations. This study also suggests that multiple tracer measurements are needed to fully characterize wildfire plumes in urban areas.

The high level of surface ozone (O3) concentration is produced from the various complex chemical reaction of oxides of nitrogen (NOx) and volatile organic compounds (VOCs) under varied meteorological conditions. It has severe effects on human health, vegetation, and as well on infrastructure. The guidelines value for surface ozone level was set 50 ppb for an 8-hours daily average by Indian National Ambient Air Quality Standard (INAAQS, 2009) and World Health Organization (WHO, 2005) for India and worldwide respectively. Identifying the primary source of high ozone events based on observation is challenging. The relationship of the surface measured O3 with carbon monoxide (CO) and water vapor content are useful to identify the possible source of origin for the increased O3 in the stratosphere, regional or local influence.The continuous observation of O3, NOx, CO at 1 minute temporal resolution along with the meteorological parameter (1-hour temporal resolution) were taken during August 2014 to April 2017. All parameters were averaged to 8-hourly for further analysis. The high ozone events were identified based on exceeding the surface ozone concentration limit as discussed above (50 ppb). The relationship of the surface measured O3 and CO (∆O3/∆CO) and water vapor were used to explain the source of high ozone such as stratospheric origin and anthropogenic activity. The HYSPLIT’s backward air mass trajectories of the height of 1000 meters for 120 hours were calculated for the site to understand the dispersion of the pollutants. During the high ozone event, the average concentration of O3, NOx, and CO was found to be 55.46 ppb, 5.19 ppb, and 0.180 ppb respectively which were lower than the normal conditions. The positive correlation of O3 with CO (∆O3/∆CO) and low water vapor mixing ratio (10.0 g/kg) indicate regional or local influence on observed high ozone events.The high ozone events were explained based on the distribution of the ozone precursors such as NOx, CO, and meteorological parameters such as relative humidity solar radiation, wind speed, and wind direction at local. The local high ozone concentration was supported by local chemistry such as the low concentration of CO and NOx. The relationship between O3 and CO was used to explain the source of high ozone events.

Soybean (Glycine max) production is seriously threatened by ground-level ozone (O3) pollution. The goal of our study is to summarize the impacts of O3 on physiology, growth, yield, and quality of soybean, as well as root parameters. We performed meta-analysis on the collated 48 peer-reviewed papers published between 1980 and 2019 to quantitatively summarize the response of soybean to elevated O3 concentrations ([O3]). Relative to charcoal-filtered air (CF), elevated [O3] significantly accelerated chlorophyll degradation, enhanced foliar injury, and inhibited growth of soybean, evidenced by great reductions in leaf area (-20.8%), biomass of leaves (-13.8%), shoot (-22.8%), and root (-16.9%). Shoot of soybean was more sensitive to O3 than root in case of biomass. Chronic ozone exposure of about 75.5 ppb posed pronounced decrease in seed yield of soybean (-28.3%). In addition, root environment in pot contributes to higher reduction in shoot biomass and yield of soybean. Negative linear relationships were observed between yield loss and intensity of O3 treatment, AOT40. The larger loss in seed yield was significantly associated with higher reduction in shoot biomass and other yield component. This meta-analysis demonstrates the effects of elevated O3 on soybean were pronounced, suggesting that O3 pollution is still a soaring threat to the productivity of soybean in regions with high ozone levels.

Volatile organic compounds (VOCs), ozone (O3), nitrogen oxides (NOx), carbon monoxide (CO), meteorological parameters, and total non-methane hydrocarbons (NMHC) were analyzed from simultaneous measurements at the MSU-IAP (Moscow State University&mdash, Institute of Atmospheric Physics) observational site in Moscow from 2011&ndash, 2013. Seasonal and diurnal variability of the compounds was studied. The highest O3 concentration in Moscow was observed in the summer daytime periods in anticyclonic meteorological conditions under poor ventilation of the atmospheric boundary layer and high temperatures (up to 105 ppbv or 210 &mu, g/m3). In contrast, NOx, CO, and benzene decreased from 8 a.m. to 5&ndash, 6 p.m. local time (LT). The high positive correlation of daytime O3 with secondary VOCs affirmed an important role of photochemical O3 production in Moscow during the summers of 2011&ndash, 2013. The summertime average concentrations of the biogenic VOCs isoprene and monoterpenes were observed to be 0.73 ppbv and 0.53 ppbv, respectively. The principal source of anthropogenic VOCs in Moscow was established to be local vehicle emissions. Yet, only about 5% of the observed isoprene was safely attributed to anthropogenic sources, suggesting significant contribution of biogenic sources into the total levels of ozone precursors. The non-linear O3&ndash, NOx dependence shows a decrease in ground-level O3 with an increase in NOx during the summers of 2011&ndash, 2013, which is typical for the VOC-sensitive photochemical regime of O3 formation. Nevertheless, during the elevated ozone episodes in July 2011, the photochemical regime of ozone production was either transitional or NOx-sensitive. Contribution of various anthropogenic and biogenic VOCs into the measured ozone values was evaluated. The ozone-forming potential (OFP) of total VOCs was 31&ndash, 67 &mu, g/m3 on average and exceeded 100 &mu, g/m3 in the top 10% of high ozone events, reaching 136 &mu, g/m3. Acetaldehyde, 1.3-butadiene, and isoprene have the highest ozone production potential in Moscow compared to that of other measured VOCs.

Air pollution and hot temperatures present two major health risks, especially for vulnerable groups such as children, the elderly, and people with pre-existing conditions. Episodes of high ozone concentrations and heat waves have been registered throughout Europe and are expected to continue to grow due to climate change. Here, several different heat and ozone wave definitions were applied to characterize the wave-type extremes for two climatically different regions, i.e., Portugal (South Europe) and Bavaria (Central Europe), and their impacts were evaluated considering each type of hazard independently but also when they occur simultaneously. Heat and ozone waves were analyzed with respect to the underlying atmospheric circulation patterns and in terms of their association with human mortality. Heat waves were identified as the most frequent wave type and, despite different climate settings, a comparable exposure to heat and ozone waves was found in Central and South Europe. Waves were associated with in-situ built-up as well as with advection of air masses. However, in Bavaria waves showed the strongest connection with autochthonous weather conditions, while for Portugal, the strongest relationship appeared for eastern and north-eastern inflow. The most severe events, as measured by excess mortality, were always associated to compound heat-ozone waves.

This study investigated ozone (O 3 ) formation conditions during two high O 3 events in July of 2018 over the New York City metropolitan and Long Island area using surface meteorological observations, surface concentration measurements of O 3 , NO 2 , CO and PM 2.5 , and tropospheric column CO, HCHO, NO 2 from TROPOMI satellite measurements. We found that both events are associated with high temperature with maximum temperature above 31 °C. However, TROPOMI data showed high tropospheric column CO and HCHO, low NO 2 and large HCHO/NO 2 ratios over the study area in Event 1; while the opposite is seen in Event 2, with lower CO and HCHO, higher NO 2 and lower HCHO/NO 2 ratios over the study area. Precursor conditions which formed the high O 3 differed. For Event 1, it was the fire-induced smoke (VOCs) that contributed to the high spike of ground-level O 3 , and most of the study area was a NOx-limited or a transitional regime. For Event 2, it was more like a normal high NO 2 event, which resulted in a more widespread VOC-limited regime.

In this paper, the execution of vapor pressure refrigeration framework is broke down with R12, R134a, R290 and R600a as working liquid. At the point when R12 refrigerant is utilized as working liquid, its outcome is high ozone exhausting potential and an unnatural weather change potential. Different exploratory examinations were completed for long haul substitution of R134a rather than R12 on account of zero ozone exhausting potential, non-combustibility, security and comparable vapor weight as that of R12. R134a has zero ozone consumption layer however there is a high a dangerous atmospheric deviation. But R600a has zero ozone exhaustion layer and negligible global warming. Unadulterated R290 or R600a is not reasonable for direct swap for R134a in light of their immersion properties. Any blends of R134a/R290/R600a at any mole part give better execution and COP level when contrasted with R12.

China experiences high ozone concentrations with highest annual 8-hour maximum concentration in eastern China of 78 μg/m3 and was followed by southern (73 μg/m3), north-western (69 μg/m3), northern (68 μg/m3), central (67 μg/m3), north eastern (65 μg/m3) and south-western China (59 μg/m3). Ozone concentration peaked in spring season in 4 (eastern, northern, north eastern & central) of 7 regions across China while lowest concentration in most regions across China was experienced in winter season with central and southern China being the only exceptions. Regions outside Asia contributed ozone to all regions across China with highest contributions in 4 (East, Central, North & Northeast) of the 7 regions. South-western China had the largest ozone contribution from outside (23%) and was followed by 16.39% outside ozone contribution in north-western China, 11.64% contribution in north eastern China, 11% contribution in northern China, 7.85% contribution in southern China, 5.28% contribution in central China while 4.56% contribution in eastern China. Policy relevant background (PRB) concentration was above 47 μg/m3 in all regions across China and contributed about 71–94% to total ozone concentration with highest PRB concentration of 65.25 μg/m3 recorded in north-west China. China recorded 93,351 (95%CI: 11001–169,898) ozone related premature mortality in 2015 with 42,673 (95%CI: 11001–69,586) respiratory mortality and 50,678 (95%CI: 0–100,312) cardiovascular mortality. Northern and eastern China recorded high ozone related mortality with 18,230 (95%CI: 4700–29,727) & 12,261 (95%CI: 3161–19,993) respiratory and 21,662 (95%CI: 0–42,877) & 14,528 (95%CI: 0–28,757) cardiovascular deaths respectively. In terms of foreign contributions, premature mortality due to ozone from outside Asia contributed the most to China with 1070 (95%CI: 276–1746) respiratory mortality and 1270 (95%CI: 0–2515) cardiovascular mortality. East Asia contributed to about 419 (95%CI: 109–679) respiratory deaths and 501 (95%CI: 0–989) cardiovascular deaths while North Asia contributed to 220 (95%CI: 56–358) respiratory mortality and 260 (95%CI, 0–515) cardiovascular mortality.

Albuquerque/Bernalillo County, New Mexico, is currently in attainment of the 2015 National Ambient Air Quality Standard (NAAQS) for ozone (70 ppb), but its ozone design values have increased in recent years. Air quality and source apportionment modeling with the Comprehensive Air Quality Model with Extensions (CAMx) was conducted for Albuquerque/Bernalillo County to develop a refined understanding of ozone source apportionment in the region, estimate ozone concentrations in the year 2025 based on projected changes in anthropogenic emissions, and evaluate the sensitivity of future ozone concentrations to various changes in local and non-local emissions. The study focused on two ozone episodes during June and July 2017 when 8-hr average ozone concentrations were greater than 70 ppb. Based on the modeling results, ozone during the June 2017 episode was found to be driven largely by contributions from non-local and regional emissions, whereas ozone during the July 2017 episode was driven more strongly by local emissions from within Albuquerque/Bernalillo County. On high ozone days, anthropogenic emissions from within Albuquerque/Bernalillo County contributed between 8% and 19% (6–14 ppb) of total ozone. Half of this local ozone contribution was from on-road mobile sources. Fire emissions contributed as much as 2 ppb of ozone on a given day. Contributions from large power plants in New Mexico were as large as 1 ppb on a given day but less than 0.5 ppb on most days. Modeled ozone concentrations in Albuquerque/Bernalillo County were also sensitive to emissions from oil and gas emissions in New Mexico. If projected emission reductions by 2025 materialize, these reductions could reduce future peak 8-hr average ozone concentrations by as much as 3–4% compared to 2017 values. Implications: The results of this study have important implications for air quality management in Albuquerque/Bernalillo County. Ozone in Albuquerque/Bernalillo County is the result of local and non-local emissions, is impacted by wildfires, and is sensitive to statewide oil and gas emissions. The magnitude of modeled contributions from anthropogenic emissions within Albuquerque/Bernalillo County is strongly influenced by meteorological conditions, transport pathways, and the presence of wildfire. This modeling is important for understanding the potential effectiveness of local emission controls in Albuquerque/Bernalillo County, and can serve as a basis for testing future regional and local emission control options.

In this paper, I used multivariate linear regression analysis to determine if latitude and ozone concentration predict Covid-2019 cases in 34 countries worldwide. Data pertaining to Covid-2019 cases were extracted from Worldometer. Ozone concentration levels were taken from the open-access database of World Ozone and Ultraviolet Radiation Data Centre (WOUDC). Latitude of specific area where measurement took place was also provided in the database. Preliminary Kendall rank correlation test revealed that Covid-2019 incidence was positively and significantly related to ozone concentration; however, incidence was not significantly related to latitude. Using multivariate linear regression, a statistically significant link between ozone concentration and Covid-2019 incidence in 34 countries was established; however, I found no statistical association between latitude and Covid-2019 incidence refuting previous claims. Prompt health actions should be developed for areas with high ozone concentration in the present and possibly, future outbreaks; however, extensive laboratory analysis should be conducted to further confirm the findings of the study. Nevertheless, the results of this study could serve as a basis for further clinical and large-scale studies.

This study investigates the potential factors that contribute to frequent high levels of ozone in Bangu, one of the most critical areas in the city of Rio de Janeiro, regarding ozone levels and air quality. Speciated non-oxygenated volatile organic compounds (VOCs) were measured using method TO-15 (US EPA). The measured concentrations and kinetic and mechanistic analysis of VOC reactivity showed that alkanes were the most important compounds. Ozone concentrations were simulated for a base case representing a day with high ozone levels. Simulated results and statistical multivariate analysis showed that the high ozone concentrations did not seem to be closely related to local emissions but rather were related to pollutant transport and low measured NOx levels and were triggered by photochemical activity. The differences between weekdays and weekends were also investigated, showing that ozone concentrations were also higher during weekends, mainly on Sunday, when the diesel heavy vehicle fleet was reduced and lower NO emissions were observed. The VOC/NOx ratios correspond to a VOC-limited process, which leads to higher ozone concentrations under low NOx conditions.

The Korea – United States Air Quality Study (May – June 2016) deployed instrumented aircraft and ground-based measurements to elucidate causes of poor air quality related to high ozone and aerosol concentrations in South Korea. This work synthesizes data pertaining to aerosols (specifically, particulate matter with aerodynamic diameters

Dyspnea is one of the most disturbing symptoms for patients with chronic obstructive pulmonary disease (COPD) or heart failure (HF). This study investigated dyspnea triggers and factors associated with worsening dyspnea in patients with COPD or HF. COPD support group members and HF patients with reduced ejection fraction (HFrEF) and no airway obstruction answered a questionnaire describing different weather conditions (rising/falling air pressure, sunny, foggy, rainy, windy, snowy, hazy, high ozone levels, and airborne pollen) and environmental circumstances (cooking, grilling, perfumes, cigarette smoke, gasoline odor, and flower scents) and were asked to estimate the occurrence and severity of dyspnea under these conditions using predefined scales. 230 patients with COPD and 90 with HFrEF (left ventricular ejection fraction 34 ± 10%, Tiffeneau index > 70%) were analyzed. COPD patients reported dyspnea more often than HF patients in almost all weather and environmental conditions (p = 0.004 to p

Background Studies that seek to link the impact of ozone with mortality display a number of uncertainties. This study sought to ascertain the functional relationship between ozone and mortality, and analyse its short-term impact on daily natural-, respiratory- and circulatory-cause mortality in Spain. Methods We analysed data on daily natural- (ICD 10: A00-R99), respiratory- (ICD 10: J00-J99) and circulatory-cause mortality (ICD 10: I00-I99) for each of Spain's 52 provinces across the period 2000–2009. We calculated the impact of ozone on mortality by reference to relative risks (RRs) using generalised linear models, and performed an overall meta-analysis. Attributable mortality was calculated on the basis of RRs. Results A quadratic relationship was observed and the existence of a threshold value identified in 33 of the 46 monitoring stations judged to be valid for ozone data, this threshold value was located above the 80th percentile. The overall RRs for 10 μg/m3 increases in concentrations of the O3 threshold value were as follows: 1.033 (95%CI: 1.023–1.044) for natural causes; 1.089 (95%CI: 1.058–1.120) for respiratory causes; and 1.025 (95%CI: 1.018–1.033) for mortality circulatory causes. The annual total of natural-cause ozone-attributable deaths was 499 (95%CI: 277–717), 126 of which (95%CI: 54–194) were due to respiratory causes and 167 (95%CI: 39–293) to circulatory causes. Conclusions High ozone concentrations display a quadratic relationship with daily mortality. While this effect is more pronounced in respiratory causes, there is also a short-term effect on natural- and circulatory-cause mortality.

High emissions of volatile organic compounds (VOCs) from the petrochemical industry and vehicle exhaust may contribute to high ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP). In this study, the vertical profiles of VOCs were created for the southern Taiwan industrial city of Kaohsiung. Vertical air samples were collected up to 1000 m using an unmanned aerial vehicle (UAV). In Renwu District, VOC distribution was affected by the inversion layer up to 200 m height. Total VOCs (36–327 ppbv), OFP (66–831 ppbv) and SOAFP (0.12–5.55 ppbv) stratified by height were the highest values at 300 m. The VOCs originated from both local and long-distance transport sources. These findings can be integrated into Kaohsiung's future air quality improvement plans and serve as a reference for other industrialized areas worldwide.

High surface ozone concentrations, which usually occur when photochemical ozone production takes place, pose a great risk to human health and vegetation. Air quality models are often used by policy makers as tools for the development of ozone mitigation strategies. However, the modeled ozone production is often not or not enough evaluated in many ozone modeling studies. The focus of this work is to evaluate the modeled ozone production in Europe indirectly, with the use of the ozone–temperature correlation for the summer of 2010 and to analyze its sensitivity to precursor emissions and meteorology by using the regional air quality model, the Comprehensive Air Quality Model with Extensions (CAMx). The results show that the model significantly underestimates the observed high afternoon surface ozone mixing ratios (≥ 60 ppb) by 10–20 ppb and overestimates the lower ones (

Large urban areas, commonly referred to as megacities, generally consume a huge amount of energy due to the high population density along with concentrated economic activities, and the resulting environmental burden—including air pollution—is an ongoing scientific and public issue. As several common factors and drivers cause air pollution problems in urban areas, it is widely thought that the air quality trends in different cities exhibit similarities in certain aspects correlated with urban development activity and air pollution mitigation practices. However, unique characteristics in the emission, chemistry, and dispersion of air pollutants that are specific to each urban area also exist, which often reflect differing approaches to air pollution control policy. Based on this reasoning, several comprehensive studies in big megacities, mostly in North America and Europe, have been implemented extensively over the last two decades. However, the air quality is often much poorer in the megacities of developing countries, and extensive research is still needed to tackle the urgent goals of understanding the increasing complexity of air quality and identifying appropriate mitigation measures. This MAPS (Megacity Air Pollution Studies) special issue highlights recent scientific findings from megacity air-quality research in many parts of the world. It focuses primarily on the mechanisms and drivers that result in high ozone and aerosol events in megacities but also addresses the latest advances in precursor emissions inventories, chemical transformation assessments, and forecasting models with sets of field observations, including remote sensing applications.

Sichuan Province, the most industrialized and populated region in southwestern China, has been experiencing severe ozone pollution in the boreal warm season (April–September). With a surface ozone monitoring network and reanalysis dataset, we find that nearly all cities in Sichuan Province showed positive increasing trends in the warm-season ozone levels. The warm-season daily maximum 8-h average (MDA8) ozone levels increased by 2.0 ppb (4.8%) year−1 as a whole, with slightly larger trends in some sites such as a site in Zigong (5.2 ppb year−1). Seasonally, the monthly ozone level in Sichuan peaks from May to August (varies with year). The predominant warm-season synoptic patterns were objectively identified based on concurrent hourly meteorological fields from ERA5. High-pressure systems promote ozone production and result in high ozone concentrations, due to strong solar radiation as well as hot and dry atmospheric conditions. The increased occurrence of high-pressure patterns probably drives the ozone increase in Sichuan. When ozone pollution is relatively weak (with MDA8 ozone around 170 μg m−3), the air quality standard could be achieved in the short term by a 25% reduction of NOx and VOCs emissions. Strengthened emission control is needed when ozone pollution is more severe. Our study provides implications for effective emission control of ozone pollution in Sichuan.

Long-term ozone lidar routine measurements are sparse in China. In this study, we used one year of continuous ozone lidar measurements to systematically investigate the effects of synoptic patterns on the vertical structure of ozone during high ozone episodes in Hong Kong. The height of the near-surface ozone layer was identified and compared with that of the mixing layer. The results showed that Hong Kong was greatly affected by ozone transport from the Pearl River Delta region when a tropical cyclone (“C” pattern) or a trough (“T” pattern) existed. When a high-pressure center was located to the north (“H” pattern) or when both a high-pressure system and a tropical cyclone existed (“CH” pattern), Hong Kong was affected by ozone transport from southeastern or southern China. Substantial amounts of ozone were transported within a layer near the ground with an average height of 0.83, 0.75, 0.94, and 0.85 km under the C, H, CH, and T synoptic patterns, respectively. Variation in the near-surface ozone layer height was consistent with that of the mixing layer height. Weak vertical mixing resulted in a shallow near-surface ozone layer under the C and H synoptic patterns. Due to the combined effect of near-surface transport and suppressed vertical mixing, the ozone concentrations were extremely high near the ground but rapidly declined with height under the C synoptic pattern. Our investigations of the vertical structure of ozone contribute to filling the knowledge gap between synoptic patterns and the evolution of high surface ozone episodes.

The present study focused on investigating the possible atmospheric conditions influencing the high ozone episodes over a semi-urban site (27.16° N, 78.08° E) in Agra, India during July 2014–June 2016. During the study period, average concentration of ozone was 32.3 ± 22.7 ppb, and concentrations of its precursors viz carbon monoxide (CO), nitrogen oxide (NO) and total nitrogen oxides (NO x ⁎ ) were 527.3 ± 482.7 ppb, 6.5 ± 8.2 ppb, and 12.1 ± 7.8 ppb, respectively. The maximum monthly average ozone concentration was observed in June (48.2 ± 31.0 ppb) and it was nearly three times higher than the minimum levels observed in December (16.7 ± 10.5 ppb). Considering high ozone episodes, 78 days exceed hourly ozone limit of 90 ppb specified by National Air Quality Standards (NAAQS, CPCB, 2009) for India while 75 days exceed the daily maximum 8 hourly ozone limit of 70 ppb or above (NAAQS, EPA, 2015). Trajstat model was used for air-mass cluster analysis during episodic days; five clusters of air-masses were identified and among them, the cluster from northwest direction had the maximum frequency (35.4%). During the study period, four different types of high ozone episodes were identified and explained using prevailing meteorology. The episodes were attributed to local photochemistry and/or transport.