Average Pollutant Concentrations Research Articles

Spatiotemporal association between air pollution and stroke mortality in South Korea

BackgroundAir pollutant concentrations in South Korea vary greatly by region and time. To assess temporal and spatial associations of stroke subtypes with long-term air pollution effects on stroke mortality, we studied ischemic stroke (IS), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH). MethodsThis was an observational study conducted in South Korea from 2001–2018. Concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter ≤10 µm in diameter (PM10) were determined from 332 stations. Average air pollutant concentrations in each district were determined by distance-weighted linear interpolation. The nationwide stroke mortality rates in 249 districts were obtained from the Korean Statistical Information Service. Time intervals were divided into three consecutive 6-year periods: 2001–2006, 2007–2012, and 2013–2018. ResultsThe concentrations of air pollutants gradually decreased from 2001–2018, along with decreases in IS and ICH mortality rates. However, mortality rates associated with SAH remained constant. From 2001–2006, NO2 (adjusted odds ratio [aOR]:1.13, 95% confidence interval: 1.08–1.19), SO2 (aOR: 1.10, 1.07–1.13), and PM10 (aOR: 1.12, 1.06–1.18) concentrations were associated with IS mortality, and SO2 (aOR: 1.07, 1.02–1.13) and PM10 (aOR:1.11,1.06–1.22) concentrations were associated with SAH-associated mortality. Air pollution was no longer associated with stroke mortality from 2007 onward, as the air pollution concentration continued to decline. Throughout the entire 18-year period, ICH-associated mortality was not associated with air pollution. ConclusionsConsidering temporal and spatial trends, high concentrations of air pollutants were most likely to be associated with IS mortality. Our results strengthen the existing evidence of the deleterious effects of air pollution on IS mortality.

Numerical study on the cutting off performance of a novel personalized air curtain in a general consulting ward

To mitigate the risk of airborne transmission during close patient-doctor interactions in general consulting ward, a novel personalized air curtain (PAC) system is proposed to safeguard doctors against aerosol droplets. The efficacy of PAC in cutting off the patient expiratory airflow and intercepting airborne droplets was investigated through numerical simulations that examined the impact of air supply velocity and angle. Simulation results indicate that the average concentration of exhaled pollutants in the consultation room is significantly reduced by 55%–80%. A supply velocity of 1 m/s and a supply angle of 0° result in optimal pollutant concentration. Additionally, it was observed that an increase in supply air velocity during discrete phase model (DPM) simulation corresponded with an increased suspension and deposition rate which can cause to doctor infection. This study can provide effective guidance for the design and optimization of PAC in general consulting ward to reduce exposure risk and short-range infection.

Associations between residential greenness and air pollution and the incident metabolic syndrome in a Thai worker cohort.

Increasing air pollution and decreasing exposure to greenness may contribute to the metabolic syndrome (MetS). We examined associations between long-term exposure to residential greenness and air pollution and MetS incidence in the Bangkok Metropolitan Region, Thailand. Data from 1369 employees (aged 52-71years) from the Electricity Generating Authority of Thailand cohort from 2002 to 2017 were analyzed. The greenness level within 500m of each participant's residence was measured using the satellite-derived Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI). The kriging approach was used to generate the average concentration of each air pollutant (PM10, CO, SO2, NO2, and O3) at the sub-district level. The average long-term exposure to air pollution and greenness for each participant was calculated over the same period of person-time. Cox proportional hazards models were used to analyze the greenness-air pollution-MetS associations. The adjusted hazard ratio of MetS was 1.42 (95% confidence interval (CI): 1.32, 1.53), 1.22 (95% CI: 1.15, 1.30), and 2.0 (95% CI: 1.82, 2.20), per interquartile range increase in PM10 (9.5μg/m3), SO2 (0.9ppb), and CO (0.3ppm), respectively. We found no clear association between NDVI or EVI and the incidence of MetS. On the contrary, the incident MetS was positively associated with NDVI and EVI for participants exposed to PM10 at concentrations more than 50μg/m3. In summary, the incidence of MetS was positively associated with long-term exposure to air pollution. In areas with high levels of air pollution, green spaces may not benefit health outcomes.

Framework of wind joint analysis for different lake regions and its effects on the water quality

Water quality of Lake Taihu (LT) is paid wide attention, and the wind field makes wind-induced flow, significantly impacting the water quality. As a wide lake, the wind field suffers spatial and temporal changes. The correlated relationship among the wind fields for different lake regions has not been studied, and the joint effects of wind field on the water quality is still unknown. Hence, this paper proposed a framework of wind joint analysis for different lake regions and modelling its effects on the water quality, including joint analysis of wind field for different lake regions using Copula function, random time series generation of wind field using Monte-Carlo simulation, and hydrodynamic and water quality numerical simulation. Taking the Lake Taihu (LT) as study case, the joint relationships of wind field for four lake regions were analyzed, and the CODMN, TP and TN distributions under different wind fields were simulated. This paper showed the following: (1) The relationship between the wind speed and direction was weak, and the correlated relationships among the wind fields for four lake regions were significant (ρ > 0.5). (2) The water quality of LT was more influenced by the wind direction rather than the wind speed, with an impacting ratio of ∼4.5. (3) The discharged weighted angle of runoff outflow (DWARO) was a practical index to improve the water quality. When regulating the input/output runoff discharge, water diversion project and water intakes in practice, the administrations should make the DWARO less than or equal to the average wind direction, to decrease the average pollutant concentration and improve the water quality of lake and intake. The proposed framework and results of LT could be extended to other wide shallow lakes to support the environmental management and basin runoff regulation.

Spatiotemporal distribution of pollutants and impact of local meteorology on source influence on pollutants' level in a traffic air-shed in Lagos megacity, Nigeria.

Pollution from vehicular emissions is a major cause of poor air quality observed in many urban and semi-urban towns and cities. As such, this study was conducted to assess air quality and the spatiotemporal distribution of vehicular and traffic-related pollutants in several air sheds of Lagos megacity, the economic nerve centre of Nigeria. A setup of low-cost air quality sensors comprising five (5) units was deployed between November 2018 and February 2019 within traffic corridors in the heart of the city. Diurnal variation of pollutants indicated that carbon dioxide (CO2) peaked during the early hours of the day, total oxide (Ox = NO2+O3) peaked at mid-day while carbon monoxide (CO) had two distinct peaks which correspond to morning and evening rush hours. Nitrogen dioxide (NO2) concentration peaked during evening hours. Average concentrations are NO2 (97.1 ± 9.7) ppb, Ox (78.6 ± 27.2) ppb, CO2 (450.1 ± 31.2) ppm, and CO (2285.63 ± 743.7) ppb. Average concentrations of pollutants were above thresholds set by the World Health Organization (WHO) except for NO2 which was within the range permissible limits. The implication of this is that the atmosphere is polluted due to elevated concentrations of airborne pollutants, an indication which is of both health and environmental concern. The air quality index (AQI) indicates that the quality of ambient air varies from good to very unhealthy for Ox, and unhealthy to very unhealthy for CO, while AQI for PM2.5 and PM10 showed hazardous at all the sampling locations except at UNILAG where it is unhealthy for the sensitive group. For all of the sampling sites, conditional bivariate probability function (CBPF) plots show a significant agreement with the location of known pollution sources.

Emissions from international airport and its impact on air quality: A case study of beijing daxing international airport (PKX), China

The Beijing Daxing International Airport is a newly opened airport, and a comprehensive emission inventory of air pollution sources has not yet been established. The lack of basic inventory data will cause difficulties in controlling the air quality (AQ) in and around the airport. Based on actual flight data, we established a comprehensive emission inventory (carbon monoxide (CO), nitrogen oxides (NOX), hydrocarbons (HC), sulfur dioxide (SO2), particulate matter (PM), and carbon dioxide (CO2)) at Beijing Daxing International Airport. Furthermore, we evaluated the impact of airport emissions on the AQ of the surrounding areas using the ADMS-Airport model. The results showed that Beijing Daxing International Airport emitted 1.15 E+03, 1.76 E+03, 1.38 E+02, 1.16 E+02, 3.53 E+01, and 3.75 E+05 t of CO, NOX, HC, SO2, PM, and CO2, respectively, from July 1, 2020, to June 30, 2021. Engine exhaust emissions (landing and takeoff [LTO] cycles) dominated all airport pollutant emissions except for PM from the power plant. Among all aircraft types, B738 emitted the most CO2, as it accounted for almost half of all the flights. The AQ simulations showed that the air pollutant diffusion range was concentrated within 15 km of the airport and the surrounding areas. The contribution of airport emissions to NOX concentrations was most apparent under the most unfavorable meteorological conditions. Based on the average pollutant concentration during the study period, the Gu'an Li Hu Primary School station was the most affected. In particular, NOX concentrations at this station were approximately 50% higher in winter than in summer. Currently, the airport's contribution to pollution in the surrounding areas is insignificant. However, with the continuous increase in the number of flights at the airport, its impact on the AQ in the surrounding areas must be addressed in the future.

The effects of heatwave on cognitive impairment among older adults: Exploring the combined effects of air pollution and green space

The association between heatwaves and cognitive impairment in older adults, especially the joint effect of air pollution and green space on this association, remains unknown. The present cohort study used data from waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) from 2008 to 2018. Heatwaves were defined as having daily maximum temperature ≥ 92.5th, 95th and 97.5th percentile that continued at least two, three and four days, measured as the one-year heatwave days prior to the participants' incident cognitive impairment. Data on the annual average air pollutant concentrations of fine particulate matter (PM2.5) and ozone (O3) as well as green space exposure (according to the Normalized Difference Vegetation Index (NDVI)) were collected. Time-varying Cox proportional hazards models were constructed to examine the independent effect of heatwaves on cognitive impairment and the combined effect of heatwaves, air pollution, and green space on cognitive impairment. Potential multiplicative interactions were examined by adding a product term of air pollutants and NDVI with heatwaves in the models. The relative excess risk due to interaction (RERI) was calculated to reflect additive interactions. We found that heatwave exposure was associated with higher risks of cognitive impairment, with hazard ratios (HRs) and 95 % confidence intervals (CIs) ranging from 1.035 (95 % CI: 1.016–1.055) to 1.058 (95 % CI: 1.040–1.075). We observed a positive interaction of PM2.5 concentrations, O3 concentrations, lack of green space, and heatwave exposure on a multiplicative scale (HRs for product terms >1). Furthermore, we found a synergistic interaction of PM2.5 concentrations, O3, lack of green space, and heatwave exposure on an additive scale, with RERIs >0. These results suggest that extreme heat exposure may be a potential risk factor for cognitive impairment in older adults. Additionally, coexposure to air pollution and lack of green space exacerbated the adverse effects of heatwaves on cognitive function.

Comparative assessment of the risk of health disorders of the population at two industrial centers of Kuzbass from exposure to atmospheric pollution

Introduction. The high concentration of production facilities on the territory of the Kemerovo region — Kuzbass contributes to the fact that the population living in large industrial cities is affected by a high level of atmospheric pollution.
 The aim of the study to assess the risk to public health from air pollution from stationary sources in the cities of Kemerovo and Novokuznetsk.
 Materials and methods. To assess the risk we used the average of the average annual concentrations of pollutants for 2017–2021 were used. Hazard coefficients and indices, as well as carcinogenic risk, are determined according to the Guidelines 2.1.10.1920-04. The risk of chronic intoxication was determined according to the method of A.P. Shcherbo and co-authors.
 Results. Average concentrations of benz(a)pyrene exceed the hygienic standard by 3.0 times in the atmosphere of Kemerovo and by 5.8 times in Novokuznetsk. The total risk of chronic intoxication associated with atmospheric air pollution in the city of Kemerovo exceeds the acceptable level by 10.6 times, in Novokuznetsk — by 14.4 times. Benz(a)pyrene makes the greatest contribution to the formation of the risk level of chronic intoxication, accounting for 28.8% in Kemerovo and 38.4% in Novokuznetsk. The hazard indices exceed the acceptable value by 7.2 times in Kemerovo and 11.0 times in Novokuznetsk. 
 The main critical organs and systems most at risk are the respiratory organs, the immune system, and blood. The carcinogenic risk to the health of residents of Kemerovo exceeded the acceptable level by 1.43 times, Novokuznetsk — by 1.56 times. The main contribution to the formation of the level of carcinogenic risk in both cities is made by formaldehyde (83.9% — in Kemerovo and 70.5% — in Novokuznetsk).
 Limitations. The researchers have used data from official reports to calculate public health risks.
 Conclusion. Both industrial centers have a high level of atmospheric air pollution, which leads to the formation of risks to public health. The authors have identified the most unfavorable situation in Novokuznetsk.
 Ethics. This study did not require the conclusion of the Ethics Committee.

Associations between Ambient Air Pollutants and Clonal Hematopoiesis of Indeterminate Potential.

Clonal hematopoiesis of indeterminate potential (CHIP) is an age-related somatic mutation associated with incident hematologic cancer. Environmental stressors which, like air pollution, generate oxidative stress at the cellular level, may induce somatic mutations and some mutations may provide a selection advantage for persistence and expansion of specific clones. We used data from the Multi-Ethnic Study of Atherosclerosis (MESA) N = 4,379 and the Women's Health Initiative (WHI) N = 7,701 to estimate cross-sectional associations between annual average air pollution concentrations at participant address the year before blood draw using validated spatiotemporal models. We used covariate-adjusted logistic regression to estimate risk of CHIP per interquartile range increases in particulate matter (PM2.5; 4 μg/m3) and nitrogen dioxide (NO2; 10 ppb) as ORs (95% confidence intervals). Prevalence of CHIP at blood draw (variant allele fraction > 2%) was 4.4% and 8.7% in MESA and WHI, respectively. The most common CHIP driver mutation was in DNMT3A. Neither pollutant was associated with CHIP: ORMESA PM2.5 = 1.00 (0.68-1.45), ORMESA NO2 = 1.05 (0.69-1.61), ORWHI PM2.5 = 0.97 (0.86-1.09), ORWHI NO2 = 0.98 (0.88-1.10); or with DNMT3A-driven CHIP. We did not find evidence that air pollution contributes to CHIP prevalence in two large observational cohorts. This is the first study to estimate associations between air pollution and CHIP.

Heavy metals in crevalle jack, Caranx hippos, and their non-intestinal parasitic helminths from Playa las Barrancas, Alvarado, Veracruz, Mexico

In nine Caranx hippos specimens, Cd, Pb, Cr, and Cu concentration was determined in tissues (muscle and gonad) and parasites (nematodes and cestodes). The fish were caught from February to June 2019 in Las Barrancas, Alvarado Beach, Veracruz, Mexico. Heavy metals were quantified using atomic absorption spectrophotometer. The results of the average concentration of pollutants were, Cr = 0.18 ± 0.05 mg kg-1 dry weight (dw); Cu = 0.2 ± 0.1 mg kg-1 dw; Pb = 0.022 ± 0.01 mg kg-1 dw; Cd = <0.003 mg kg-1 dw. Among the tissues, Cu was the one with the highest concentration in nematodes vs. cestodes (2.2:1); vs. gonad (2.5:1); vs. muscle (2.7:1). Due to the concentration registered in Caranginema americanum nematodes could be identified as a bioindicator species for Cu pollutant. The values generally do not exceed the limits established in the Mexican National Standard (NOM-242-SSA1-2009) for Cd and Pb (0.5 mg kg-1). Records of heavy metals do not represent a health risk from consuming C. hippos.

Measurement of nitrogen oxide (NOx) emissions in fuel-combustion equipment and analysis of their impact on city air condition

The object of the research is to ensure environmental safety and maximum efficiency of fuel burning equipment. Energy facilities (thermal power plant, boiler houses) are among the biggest air polluters in the city. Nitrogen oxides (NO, NO2, NOx) occupy a significant place among the toxic gases contained in the flue gases of fuel-burning equipment. These substances have a negative impact on the ecological state of the city and are regulated by the Order of the Ministry of Natural Resources of Ukraine dated 27.06.2006 No. 309 on the approval of standards for maximum permissible emissions of pollutants from stationary sources. The principles of measurement unity are considered, including the presentation of measurement results in standard units (ppm, mg/m3). Conversion from volume concentration (ppm) to mass (mg/m3) is given. Measurements of the concentration of nitrogen oxides were carried out. In the course of research, instrumental measuring tools were used, which made it possible to obtain the values of nitrogen dioxide concentrations in gas boiler flue emissions. In particular, the average maximum concentrations of the main pollutants exceed 62.58 mg/m3. Analyzing the concentration of flue gases allows to determine the concentration of pollutants and to adjust the optimal operation of the equipment as much as possible, achieving a reduction in emissions and compliance with the approved emission standards. Obtained data on background concentrations of nitrogen dioxide in the city of Kyiv, amounting to 1.33 MPC. Using the data of instrumental measurements with the method of calculating concentrations of harmful substances in the atmospheric air and background concentrations, a map of emission dispersion was created. Fields of surface concentrations were plotted on the scattering map, which makes it possible to compare the obtained values with the hygienic standards of atmospheric air. By combining instrumental measurement methods and calculation methods, the volume of emissions was determined and the impact on atmospheric air pollution of the city was assessed.

O-214 interaction of air pollution and meteorological factors on IVF outcomes: a multicenter study in China

Abstract Study question Is there an interaction between air pollution and meteorological factors on IVF outcomes? Summary answer The correlation between air-pollutant exposure and IVF outcomes was modified by meteorological conditions, especially temperature and wind speed. What is known already Previous studies revealed associations between air-pollutant exposure and in vitro fertilization (IVF) outcomes. However, modification effects of air pollution on IVF outcomes by meteorological conditions remain elusive. Study design, size, duration Multicenter retrospective cohort study, 2015–2020. Participants/materials, setting, methods This multicenter retrospective cohort study included 15,217 women from five northern Chinese cities during 2015–2020. Daily average concentrations of air pollutants (PM2.5, PM10, O3, NO2, SO2, and CO) and meteorological factors (temperature, relative humidity, wind speed, and sunshine duration) during different exposure windows were calculated as individual approximate exposure. Generalized estimating equations and stratification models were used to assess the associations of air pollution and meteorological conditions with IVF outcomes and estimated potential interactions. Main results and the role of chance Exposure to PM2.5, SO2, and O3 was adversely correlated with pregnancy outcomes in fresh IVF cycles. Positive associations of wind speed and sunshine duration with pregnancy outcomes were detected. In addition, we observed that embryo transfer in spring and summer had a higher likelihood to achieve a live birth compared with winter. In stratified models, pieces of evidence of interaction between meteorological factors and air pollutants on pregnancy outcomes were detected. Negative associations of PM2.5 with clinical pregnancy were only significant at lower temperatures and wind speeds. Moreover, the effects of O3 on live birth were enhanced by higher quartiles of wind speed. Limitations, reasons for caution First of all, we used the data from monitoring stations to estimate the individual exposure, which was inaccurate and may introduce bias. Second, due to data limitations, this study did not discuss socio-economic factors, which were reported to be associated with spatial-temporal variations of air pollutants and reproductive outcomes. Wider implications of the findings Pregnant women should be advised to reduce outdoor time when the air quality was poor, particularly at lower temperatures. Trial registration number not applicable

Assessment of the Impact of Oil Production Processes on the Health of the Population of Oil-Producing Areas of the Irkutsk Region

Introduction. The state of the population health depends on the ecological and hygienic well-being of the territory. In places with developed oil production, there is a long-term impact of pollutants on the human body and, as a result, corresponding diseases develop. This is evidenced by numerous domestic and foreign studies, but the territory of the Irkutsk region is not covered by such studies. Therefore, the work objective is to assess the impact of oil production processes on the incidence of the population of oil-producing regions of the Irkutsk region.Materials and Methods. The source materials were the statistical indicators of overall and primary disease incidence of the population of the regions of the Irkutsk region for the period from 2016 to 2019, posted on the website of medical statistics of the Irkutsk region. For the calculation of the non-carcinogenic risk, we have used environmental monitoring data from an oil-producing company based on average daily concentrations of pollutants in oil-producing areas.Results. It is shown that oil-producing areas are characterized by extremely high incidence rates for such groups of diseases as respiratory diseases, diseases of the circulatory system, diseases of the musculoskeletal system, diseases of the digestive system, diseases of the genitourinary system, as well as deviations in pregnancy, childbirth and the postpartum period. Infant mortality rates in these territories are up to 4 times higher than the corresponding average indicators for the Irkutsk region as a whole. The calculation of non-carcinogenic risk showed an excess over the permissible values accepted in Russia.Discussion and Conclusions. The results of the analysis testify to the unfavorable medical and demographic situation in the territories under discussion. The pronounced excess of the incidence rate for the presented groups of diseases in the oilfield areas in comparison with the territories taken for comparison reflects the possible impact of environmental pollution on the health of the population. A connection between the growth of infant mortality in the territories under consideration and the beginning of the industrial development of hydrocarbon deposits in these places has been revealed. The contribution of oil companies to the socio-economic development of the regions, including co-financing of medical care for the population, could partially offset the negative impact of industrial processes.

Association between airborne particulate matter（PM 2.5） concentration and the incidence of allergic rhinitis in Shanghai

Objective:To explore the impact of PM 2.5 concentration in Shanghai on the incidence of allergic rhinitis（AR） in the population, and provide strategies for early warning and prevention of AR. Methods:Collect daily average concentrations of atmospheric pollutants monitored in Shanghai from January 1, 2017 to December 31, 2019, and clinical data of AR patients from five hospitals in Shanghai during the same period. We used a time-series analysis additive Poisson regression model to analyze the correlation between PM 2.5 levels and outpatient attendance for AR patients. Results:During the study period, a total of 56 500 AR patients were included, and the daily average concentration of PM 2.5 was（35.28±23.07）μg/m³. There is a correlation between the concentration of PM 2.5 and the number of outpatient attendance for AR cases. There is a positive correlation between the daily average number of outpatient for AR and levels of PM 2.5 air pollution（（P<0.05）） . We found that every 10 μg/m³ increase in PM 2.5, the impact of on the number of AR visits was statistically significant on the same day, the first day behind, and the second day behind, with the strongest impact being the exposure on the same day. Every 10 μg/m³ increases in PM 2.5, the number of outpatient visits increased by 0.526% on the same day（95%CI 1.000 50-1.010 04）. Conclusion:The atmospheric PM 2.5 concentration in Shanghai is positively correlated with the number of outpatient for AR, and PM 2.5 exposure is an independent factor in the onset of AR. This provides an important theoretical basis for AR.

Interaction of air pollution and meteorological factors on IVF outcomes: A multicenter study in China

BackgroundPrevious studies revealed associations between air-pollutant exposure and in vitro fertilization (IVF) outcomes. However, modification effects of air pollution on IVF outcomes by meteorological conditions remain elusive. MethodsThis multicenter retrospective cohort study included 15,217 women from five northern Chinese cities during 2015–2020. Daily average concentrations of air pollutants (PM2.5, PM10, O3, NO2, SO2, and CO) and meteorological factors (temperature, relative humidity, wind speed, and sunshine duration) during different exposure windows were calculated as individual approximate exposure. Generalized estimating equations models and stratified analyses were conducted to assess the associations of air pollution and meteorological conditions with IVF outcomes and estimate potential interactions. ResultsPositive associations of wind speed and sunshine duration with pregnancy outcomes were detected. In addition, we observed that embryo transfer in spring and summer had a higher likelihood to achieve a live birth compared with winter. Exposure to PM2.5, SO2, and O3 was adversely correlated with pregnancy outcomes in fresh IVF cycles, and the associations were modified by air temperature, relative humidity, and wind speed. The inverse associations of PM2.5 and SO2 exposure with biochemical pregnancy were stronger at lower temperatures and humidity. Negative associations of PM2.5 with clinical pregnancy were only significant at lower temperatures and wind speeds. Moreover, the effects of O3 on live birth were enhanced by higher wind speed. ConclusionsOur results suggested that the associations between air-pollutant exposure and IVF outcomes were modified by meteorological conditions, especially temperature and wind speed. Women undergoing IVF treatment should be advised to reduce outdoor time when the air quality was poor, particularly at lower temperatures.

Long term trends of dry and wet deposition of air pollutants at declining forest site of Mt. Oyama in Japan during 1994–2019

Forest decline, which occurs in mountainous regions in many countries, may result from the effects of acid fog, ozone, or deposition of other pollutants. We observed wet deposition of air pollutants at different altitudes on Mt. Oyama, situated southwest of Tokyo, for 1994 until 2019. During this period, the domestic atmospheric environment was improved in Japan. The average concentration of air pollutants around all the sampling sites on Mt. Oyama decreased by 63.01%, 32.08%, 8.80%, and 39.73% for NH3, HCl, HNO3, and SO2, respectively. The volume weighted mean (VWM) pH values showed an increasing trend for bulk deposition (+0.70% y-1), fog water (+2.58% y-1), and throughfall (+2.60% y-1). Stemflow also increased (cedar, +1.17% y-1; fir, +0.82% y-1), although it included organic acids dissolved from the stem and it primarily had a low VWM pH value. The overall pH value of the fog water increased at the site, although acidic fog was still observed. Comparing fog water between winter and summer, a significant increase in pH occurred in summer, whereas no change occurred in winter. In summer, the sources of pollutants at Mt. Oyama are mainly from mainland Japan, and the frequency of low-pH acidic fog decreased annually. In winter, Mt. Oyama was affected by transboundary pollution, and acid fog occasionally occurred. Improvements in the domestic atmospheric environment and control of transboundary pollution will provide better conditions for mountain ecology that are free from acidic pollutants.

Impacts of building-height variability on turbulent coherent structures and pollutant dispersion: Large-eddy simulations

In built-up urban areas, there are numerous buildings of various shapes and heights, and their collective impacts on urban flow and air quality are of great concern. Here, we numerically examine the impacts of building-height variability on turbulent coherent structures above an array of square buildings and pollutant dispersion using a large-eddy simulation model. Three simulations are conducted: no building-height variability case (σ/H = 0, where σ is the standard deviation of building heights and H is the average building height), small building-height variability case (σ/H = 0.25), and large building-height variability case (σ/H = 0.5). In the latter two cases, buildings of two different heights are alternately arranged. Pollutants are released from street level. As the building-height variability increases, the average pedestrian-level pollutant concentration decreases and its spatial variability becomes large. The building-height variability greatly influences turbulence intensity and vertical turbulent momentum and pollutant fluxes. The streamwise-elongated low- and high-speed flow structures appear in all three cases, and they are wider in the spanwise direction when there is building-height variability. Strong turbulent fluctuations seem to affect the spanwise extension of the high- and low-speed flow structures. Quadrant analysis shows that stronger ejection and sweep events are more frequent with increasing building-height variability. The regions of ejection (sweep) well coincide with those of pollutant ejection (pollutant sweep). When there is building-height variability, the streaky structures that appear also in the fields of instantaneous vertical turbulent momentum flux are somewhat wider in the spanwise direction.

On accounting for emissions of pollutants from autonomous heat supply sources of individual residential buildings when conducting summary calculations of atmospheric air pollution for settlements

Introduction. Autonomous sources of heat supply (ASHS) can make a crucial contribution to the level of atmospheric air pollution in settlements. However, emissions from ASHS in most cases are either not included in the summary calculations of atmospheric air pollution at all or estimated with significant uncertainties. &#x0D; The purpose of this study was a hygienic assessment of methods and results of accounting for emissions of pollutants from the ASHS of individual residential buildings when conducting summary calculations of atmospheric air pollution for settlements. &#x0D; Materials and methods. the original methodology of a phased survey of the city’s ASHS was used and the results of summary calculations of atmospheric air pollution in 18 cities conducted using this methodology are presented. Calculations of single, average seasonal (for the cold period) and average annual surface concentrations of pollutants were carried out in accordance with current regulatory documents using the unified software for calculating atmospheric pollution (UPRZA) “Ecologist-city”. In all the studied cities a significant number of sources of atmospheric air pollution was established to be ASHS. In more than 90% of these sources, coal and firewood were used as energy carriers. The greatest excess of hygienic standards of atmospheric air quality was noted &#x0D; for benz(a)pyrene. In 15 cities, the highest calculated maximum single surface concentration of at least one pollutant created by emissions from ASHS exceeded the maximum allowable single concentration (MACs). &#x0D; Limitations of the study are due to the fact that direct instrumental measurements to determine the characteristics of emissions from ASHS into the atmosphere are impossible. &#x0D; Conclusions. The area of the city’s territory where the estimated maximum single surface concentration of at least one pollutant exceeded the MACs, reached 45%, and the seasonal average concentration exceeded maximum allowable average annual concentration on 50% of the territory. The most effective measure to reduce air pollution by emissions from ASHS is the replacement of solid and liquid mineral fuels with natural gas. Unification of methods of accounting and inventory of ASHS as sources of atmospheric air pollution is required.

New insights on precise regulation of pollutant distribution inside a street canyon by different vegetation planting patterns.

Mixed-vegetation planting patterns are commonly seen in urban areas for specific reasons like aesthetic, cooling, and particle deposition effects of the vegetation. However, they may have a negative impact on human health by worsening the air quality inside the street canyon due to the decreased air exchange rate. From the view of precise control of pollutant concentration in the sensitive areas of people's concern in the existed street canyons, thirty-four cases with different vegetation planting patterns and pressure loss coefficients (λ) are studied numerically to investigate the effects of vegetation on airflow and pollutant dispersion inside the canyon. The cases of treeless and 2 rows of tree planting patterns in wind-tunnel measurements were selected for the model validation. The results demonstrate that compared to the treeless case, the greenbelts can greatly change the airflow features and reduce the pollutant concentration at the leeward side, while the only-tree planting patterns have little impact on the flow and deteriorate dispersion within the street canyon. Moreover, rows of greenbelts planted under the corresponding trees can reduce the average pollutant concentrations on the leeward wall and the footpath of the street canyon by up to 22.6% and 33.2%, respectively. Besides, the pattern of 1 row of trees with 1 row of greenbelts planted in the street canyon center should be suggested as the optimal mixed vegetation configuration in this study. That is because compared to the treeless case the pollutant concentration on leeward wall, windward wall, leeward footpath, and windward footpath can be reduced by 14.2%, 10.0%, 24.6%, and 37%, respectively. It is helpful to the city planners to consider whether the disadvantages of planting vegetation inside the street canyon would overwhelm the advantages.

Unexpected association between ambient ozone and adult insomnia outpatient visits: A large-scale hospital-based study

Growing evidence indicates that short-term ozone (O3) exposure has substantial health consequences, but the relationship between short-term ambient O3 and insomnia, a common sleep disorder, is not clear. This study aimed to investigate the short-term effects of ambient O3 exposure on outpatient visits for adult insomnia and to explore the potential modifiers. A large-scale multihospital-based study was carried out in Chongqing, the largest city in Southwest China. Daily data on outpatient visits for adult insomnia, average concentrations of ambient air pollutants and meteorological factors were collected. We conducted quasi-Poisson regression with generalized additive model to assess the association between ambient O3 and outpatient visits for adult insomnia in varied windows of exposure. Subgroup analyses were applied to identify its modifiers. Totally, 140,159 adult insomnia outpatient visits were identified. The daily maximum 8-h average concentration of O3 was 69 μg/m3 during the study period, which greatly below the updated Chinese and WHO recommended limits (daily maximum 8-h average, O3: 100 μg/m3). Short-term O3 exposure was significantly negatively associated with outpatient visits for adult insomnia in different lag periods and the greatest decrease of outpatient visits for adult insomnia was found at lag 02 [0.93% (95% CI: 0.48%, 1.38%)]. Additionally, stronger links between O3 and adult insomnia outpatient visits were presented in cool seasons, and we did not observe any significant modified effects of gender and age. Moreover, the negative O3-insomnia association remained robust after controlling for other common air pollutants and comorbidities. In summary, short-term exposure to lower level of ambient O3, was associated with reduced daily outpatient visits for adult insomnia and such association showed to be more obvious in cool seasons.