Aerosol Air Research Articles

Effect of large topography on atmospheric environment in Sichuan Basin: A climate analysis based on changes in atmospheric visibility

Using 51 years (1960–2010) of observations from meteorological stations in the Sichuan-Chongqing region, including atmospheric visibility as a proxy for aerosol concentration, relative humidity, air temperature, wind speed and FNL reanalysis data (1°×1°) of air temperature, pressure and wind, and the altitude of each station, a linear trend and multivariate fitting approach was used to explore the effects of the large topography on the atmospheric environment in the Sichuan-Chongqing region. The region mainly consists of two areas: Sichuan Basin (SCB) and Western Sichuan Plateau (WSP; eastern part of the Tibetan Plateau). Visibility was relatively low in the SCB and high in the WSP, indicating the high and low levels of aerosols respectively in the SCB and the WSP. Additionally, visibility and wind speed were positively correlated within the basin (altitude below 750 m), while negatively correlated at stations above 1,500 m, such as on the WSP, indicating that the topography had an influence on the atmospheric environment of the basin. On the one hand, the vertical structures of the wind fields and the vertical profiles of latitudinal deviations in wind speed and air temperature in the basin show that the unique large topography causes a “harbour” effect on the leeward-slope of the WSP, with the SCB being a weak wind region, while the descending air currents in the upper westerlies of the basin form a huge “vault” of air. On the other hand, topographic effects can make the basin more susceptible to the formation of inversion structures near the surface and at high altitudes, thus stabilising the atmosphere. The topographic effects, which is not conducive to horizontal diffusion and convective transport of pollutants, were the most significant in winter, followed by autumn and spring.

Flame structure and burning velocity of flames propagating in binary iron aerosols

A numerical study was performed for binary dispersed iron aerosols in air using different particle sizes with constant average particle size. The effects of particle size and density of the two aerosols on flame structure and speed are systematically investigated. Varying the amount of small and big particles results in separated and overlapped flame fronts. For higher values of particle size ratio (ratio between the size of big and small particles) and density of small particles, flame fronts are observed to overlap. The flame speed of the binary mixture is compared with the mono-dispersed case and the difference is analyzed for different particle size ratios. The addition of a small fraction of small particles in the binary mixture is found to result in a substantial increase in the flame speed if the particle size ratio is large. Detailed analyses on the variation of the total amount of fuel shows the particle size ratio determines the equivalence ratio at which the maximum flame speed occurs. The maximum flame speed as a function of equivalence ratio was observed to move from the lean to the rich side for particle size ratio sufficiently large enough.

Practical approach for an easy determination of the limit of detection and uncertainty budget associated with on-line measurements of gas and aerosols by ion chromatography

The Monitor for Aerosols and Gases in Ambient air (MARGA) is an on-line gas and aerosol sampling and analysis system based on ion chromatography (IC) that allows the monitoring at 1-h time resolution of major water-soluble atmospheric species in the gas phase (NH3, HCl, HONO, HNO3, SO2) and the particle phase (NH4+, Na+, K+, Ca2+, Mg2+, Cl−, NO3−, SO42−). The lack of a common procedure among users to determine the LOD and the uncertainty of measurements for each species led to the comparison of four different operational approaches for the LOD determination, one manual and three automatic. This comparison highlighted the high NO3− blank values around 0.6 μg m−3 when using a HNO3-based cation eluent, so the p-TSA-based eluent was proposed instead. A model for an easy estimation of measurement uncertainties is suggested based on main sources of uncertainty (liquid sample volume, air volume, representativeness of the sample, accuracy of the internal standard preparation, chemical background, repeatability), applied to a real dataset acquired in a rural site in the North of France. It gives relative average uncertainties between 5 and 30% for NH3, HONO, HNO3, SO2, NH4+ NO3− and SO42−, while Na+, K+, Ca2+, Mg2+ and Cl− range between 45% and >100%. A comparison between our dataset and other studies confirmed that the variation of the uncertainty budget depends on environmental concentrations of the species and site typology. The practical recommendations drawn in this paper may be helpful to the user community of gas and aerosol online samplers coupled to IC analysis.

A New Chemistry-Climate Model GRIMs-CCM: Model Evaluation of Interactive Chemistry-Meteorology Simulations

We describe a new chemistry-climate model, Global/Regional Integrated Model system Chemistry Climate Model (GRIMs-CCM), developed by coupling the chemistry modules of the GEOS-Chem chemical transport model to the GRIMs general circulation model. The GRIMs-CCM is driven by meteorological variables simulated by the GRIMs and uses simulated gas and aerosol concentrations to calculate the radiative transfer equations at each time step. The model is evaluated by comparing ozone and aerosol concentrations with respective observations from the surface networks and the satellite datasets. It is found that the GRIMs-CCM successfully reproduces the observed spatial distributions of annual-mean aerosol optical depth and captures the seasonal and latitudinal variations of total column ozone. The evaluation of simulated aerosols in surface air against the observations reveals that the model reproduces the observed temporal and spatial variations but shows biases in soil dust aerosols. We also estimate the climatic impact of aerosols by conducting two sets of 10-year simulations for the preindustrial and present conditions. The GRIMs-CCM shows the aerosol radiative forcing of − 0.30 W m−2 from the preindustrial to present-day climates, comparable to the values from other climate model intercomparison projects. These results suggest that the GRIMs-CCM is suitable for studying chemistry-climate interactions and their changes over time.

Impact of Inter-Annual Variation in Meteorology from 2010 to 2019 on the Inter-City Transport of PM2.5 in the Beijing–Tianjin–Hebei Region

Air pollution has become a great challenge to achieving sustainable development. Among the pollutants, aerosols significantly affect human health and play an important role in global climate change. The concentration of aerosols in the ambient air is influenced strongly by the regional transport of pollutants and their precursors and may vary considerably under different meteorological conditions in different years. This inter-annual variation in meteorology may yield conflicting results in the quantification of the contribution from regional transport of air pollutants. It creates uncertainty for local governments to develop pollution control measures to reduce the challenges to sustainable development. Previous studies on this issue are often year-specific or cover short time spans, and the inter-city transport of air pollutants in the long term is still not fully understood. Therefore, in this study, the Weather Research and Forecasting (WRF) model and Community Multiscale Air Quality (CMAQ) model was used to assess inter-annual variations in the contribution of inter-city transport to the PM2.5 concentration in the Beijing–Tianjin–Hebei region from 2010 to 2019. To highlight the impact of inter-annual variations in meteorology, the authors used the same emission inventory and the same model configurations for the 10-year simulation. The major findings can be summarized as follows: (1) Both PM2.5 concentration and inter-city transport in the Beijing–Tianjin–Hebei (BTH) region were influenced by the inter-annual variation in meteorological conditions. (2) The simulated annual average concentrations in 13 cities in BTH are highly variable, with fluctuations ranging from 30.8% to 54.1%, and more evident variations were found in seasonal results. (3) Seven out of thirteen cities have a contribution from regional transport exceeding 50%, which are located in the eastern half of the Beijing–Tianjin–Hebei region. (4) The magnitude of the regional transport contribution varies significantly among the cities of BTH, on an annual basis, from a minimum inter-annual fluctuation of 8.9% to a maximum of 37.2%, and seasonal fluctuation is even more strongly evident. These results indicate that, when formulating pollution control strategies, inter-annual changes in meteorological conditions should not be ignored.

Development, characterization, and application of an improved online reactive oxygen species analyzer based on the Monitor for AeRosols and Gases in ambient Air (MARGA)

Abstract. Excessive reactive oxygen species (ROS) in the human body is an important factor leading to diseases. Therefore, research on the content of reactive oxygen species in atmospheric particles is necessary. In recent years, the online detection technology of ROS has been developed. However, there are few technical studies on online detection of ROS based on the dithiothreitol (DTT) method. Here, to modify the instrument, a DTT experimental module is added that is protected from light and filled with nitrogen at the end based on the Monitor for AeRosols and Gases in ambient Air (MARGA). The experimental study found that the detection limit of the modified instrument is 0.024 nmol min−1. The DTT consumption rate of blank sample (ultrapure water) is reduced by 44 %, which eliminates the influence of outside air and light in the experiment. And the accuracy of the online instrument is determined by comparing the online and offline levels of the samples, which yielded good consistency (slope 0.97, R2=0.95). It shows that the performance of the instrument is indeed optimized, the instrument is stable, and the characterization of ROS is accurate. The instrument not only realizes online detection conveniently and quickly, but also achieves the hour-by-hour detection of ROS based on the DTT method. Meanwhile, reactive oxygen and inorganic ions in atmospheric particles are quantified using the online technique in the northern suburbs of Nanjing. It is found that the content of ROS during the day is higher than that at night, especially after it rains; ROS peaks appear in the two time periods of 08:00–10:00 and 16:00–18:00 (China Standard Time, UTC+8:00; expressed here in local time – LT). In addition, examination of the online ROS, water-soluble ion (SO42-, NO3-, NH4+, Na+, Ca2+, K+), BC, and polluting gas (SO2, CO, O3, NO, NOx) measurements revealed that photo-oxidation and secondary formation processes could be important sources of aerosol ROS. This breakthrough enables the quantitative assessment of atmospheric particulate matter ROS at the diurnal scale, providing an effective tool to study sources and environmental impacts of ROS.

Assessing Exposures from the Deepwater Horizon Oil Spill Response and Clean-up.

The GuLF Study is investigating adverse health effects from work on the response and clean-up after the Deepwater Horizon explosion and oil release. An essential and necessary component of that study was the exposure assessment. Bayesian statistical methods and over 135 000 measurements of total hydrocarbons (THC), benzene, ethylbenzene, toluene, xylene, and n-hexane (BTEX-H) were used to estimate inhalation exposures to these chemicals for >3400 exposure groups (EGs) formed from three exposure determinants: job/activity/task, location, and time period. Recognized deterministic models were used to estimate airborne exposures to particulate matter sized 2.5 µm or less (PM2.5) and dispersant aerosols and vapors. Dermal exposures were estimated for these same oil-related substances using a model modified especially for this study from a previously published model. Exposures to oil mist were assessed using professional judgment. Estimated daily THC arithmetic means (AMs) were in the low ppm range (<25 ppm), whereas BTEX-H exposures estimates were generally <1000 ppb. Potential 1-h PM2.5 air concentrations experienced by some workers may have been as high as 550 µg m-3. Dispersant aerosol air concentrations were very low (maximum predicted 1-h concentrations were generally <50 µg m-3), but vapor concentrations may have exceeded occupational exposure excursion guidelines for 2-butoxyethanol under certain circumstances. The daily AMs of dermal exposure estimates showed large contrasts among the study participants. The estimates are being used to evaluate exposure-response relationships in the GuLF Study.

Preface

Abstract The 2021 The Air Quality and Climate Change (1st AQCC) and The 3rd Malaysia Air Quality Annual Symposium (MAQAS) organized by Clean Air Forum Society of Malaysia (MyCAS) and supported by Department of Environment Malaysia (Air Division) and Taiwan Association for Aerosol Research (TAAR) was held on the 17th–18th November 2021 in virtual form. Due to the Covid-19 pandemic, “Combating Climate Change and Improving Air Quality in a Global Pandemic” was chosen as the theme of this year’s conference. High challenges have been faced by our team members to manage this event due to the Covid-19. However, with the collaboration and hard work among committee members and participants this event was successfully conducted virtually and managed remotely from Bangi Resort Hotel, Putrajaya and from University Malaysia Terengganu as a second centre. With that, the conference had emphasized interdisciplinary research along with practices and fosters exchanges among tiscientists, practitioners, professionals and young researchers in finding solutions and sharing latest technology in aerosol and air quality studies and work during this situation. It was an honour to receive more than 50 papers submitted to the conference and I am very pleased to announce that around 17 papers have been selected to be published in the IOP proceeding. All papers which have been accepted were subjected to a rigorous peer-reviewing process to ensure quality and consistency. Hence, it is vital to tackle air quality issues. The conference also served as an opportunity in establishing networking among scientists, practitioners, professionals and young researchers in international regions in strengthening international collaboration. A wide range of topics was covered from fundamental, applied and technology aspects of aerosol science and air quality that focused on monitoring, control strategies, health impact, policy and management, big data and air pollution modelling using earth observation data, atmospheric transport and emissions from combustion process. I acknowledge with gratitude the assistance rendered by the scientific team of 2021 AQCC and MAQAS was led by Prof. Dr Juliana Jalaludin and her publication team along-with all the track chairs with continuous support and advice led to the smooth publication of this issue. Last, but not least, we thank the authors, reviewers and the conference secretariat for their contribution which has enabled this publication to become a reality. Hopefully, all participants and other interested readers will benefit scientifically from the proceedings and also find it stimulating in the process. With our warmest regards, Ts Dr Noor Zaitun Yahaya (AHEA) The Conference Chair lists are available in the pdf

Identifying chemical aerosol signatures using optical suborbital observations: how much can optical properties tell us about aerosol composition?

Abstract. Improvements in air quality and Earth's climate predictions require improvements of the aerosol speciation in chemical transport models, using observational constraints. Aerosol speciation (e.g., organic aerosols, black carbon, sulfate, nitrate, ammonium, dust or sea salt) is typically determined using in situ instrumentation. Continuous, routine aerosol composition measurements from ground-based networks are not uniformly widespread over the globe. Satellites, on the other hand, can provide a maximum coverage of the horizontal and vertical atmosphere but observe aerosol optical properties (and not aerosol speciation) based on remote sensing instrumentation. Combinations of satellite-derived aerosol optical properties can inform on air mass aerosol types (AMTs). However, these AMTs are subjectively defined, might often be misclassified and are hard to relate to the critical parameters that need to be refined in models. In this paper, we derive AMTs that are more directly related to sources and hence to speciation. They are defined, characterized and derived using simultaneous in situ gas-phase, chemical and optical instruments on the same aircraft during the Study of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS, an airborne field campaign carried out over the US during the summer of 2013). We find distinct optical signatures for AMTs such as biomass burning (from agricultural or wildfires), biogenic and polluted dust. We find that all four AMTs, studied when prescribed using mostly airborne in situ gas measurements, can be successfully extracted from a few combinations of airborne in situ aerosol optical properties (e.g., extinction Ångström exponent, absorption Ångström exponent and real refractive index). However, we find that the optically based classifications for biomass burning from agricultural fires and polluted dust include a large percentage of misclassifications that limit the usefulness of results related to those classes. The technique and results presented in this study are suitable to develop a representative, robust and diverse source-based AMT database. This database could then be used for widespread retrievals of AMTs using existing and future remote sensing suborbital instruments/networks. Ultimately, it has the potential to provide a much broader observational aerosol dataset to evaluate chemical transport and air quality models than is currently available by direct in situ measurements. This study illustrates how essential it is to explore existing airborne datasets to bridge chemical and optical signatures of different AMTs, before the implementation of future spaceborne missions (e.g., the next generation of Earth Observing System (EOS) satellites addressing Aerosols, Cloud, Convection and Precipitation (ACCP) designated observables).

Indoor air pollution effects on pediatric asthma are submicron aerosol particle-dependent.

The school environment is crucial for the child's health and well-being. On the other hand, the data about the role of school's aerosol pollution on the etiology of chronic non-communicable diseases remain scarce. This study aims to evaluate the level of indoor aerosol pollution in primary schools and its relation to the incidence of doctor's diagnosed asthma among younger school-age children. The cross-sectional study was carried out in 11 primary schools of Vilnius during 1year of education from autumn 2017 to spring 2018. Particle number (PNC) and mass (PMC) concentrations in the size range of 0.3-10µm were measured using an Optical Particle Sizer (OPS, TSI model 3330). The annual incidence of doctor's diagnosed asthma in each school was calculated retrospectively from the data of medical records. The total number of 6-11years old children who participated in the study was 3638. The incidence of asthma per school ranged from 1.8 to 6.0%. Mean indoor air pollution based on measurements in classrooms during the lessons was calculated for each school. Levels of PNC and PMC in schools ranged between 33.0 and 168.0 particles/cm3 and 1.7-6.8µg/m3, respectively. There was a statistically significant correlation between the incidence of asthma and PNC as well as asthma and PMC in the particle size range of 0.3-1µm (r = 0.66, p = 0.028) and (r = 0.71, p = 0.017) respectively. No significant correlation was found between asthma incidence and indoor air pollution in the particle size range of 0.3-2.5 and 0.3-10µm. Conclusion: We concluded that the number and mass concentrations of indoor air aerosol pollution in primary schools in the particle size range of 0.3-1µm are primarily associated with the incidence of doctor's diagnosed asthma among younger school-age children. What is Known: •Both indoor and outdoor aerosol pollution is associated with bronchial asthma in children. What is New: •The incidence of bronchial asthma among younger school age children is related to indoor air quality in primary schools. • Aerosol pollutants in the size range of 0.3-1 µm in contrast to larger size range particles can play major role in the etiology of bronchial asthma in children.

ВЛИЯНИЕ СИЛЬНОГО АЭРОЗОЛЬНОГО ЗАГРЯЗНЕНИЯ ВОЗДУХА НА ЭВОЛЮЦИЮ КОНВЕКТИВНЫХ ОБЛАКОВ ВО ВРЕМЯ ГРОЗЫ В КИТАЕ ПО РЕЗУЛЬТАТАМ ТРЕХМЕРНОГО ЧИСЛЕННОГО МОДЕЛИРОВАНИЯ

Numerical simulation of evolution of a convective cloud and precipitation during a thunderstorm event that took place on August 11, 2017 in Beijing (China) against a background of high aerosol air pollution was performed using a numerical nonstationary three-dimensional model. Different microphysical parameters of drops and ice particles which depend on aerosol pollution of the atmosphere, were varied: an autoconversion threshold for cloud droplets and raindrops and parameters of raindrop and hailstone size distribution. It was found for this case that liquid drops do not play a significant role in the convective cloud evolution. The effect of aerosol pollution both on the raindrop size spectrum and on the transition of cloud droplets to raindrops does not influence significantly dynamic, microphysical and electrical properties of the cloud. At the same time, the change in the ice particle spectrum towards the size decrease that happens under the influence of increased aerosol pollution, has a significant impact on the evolution of the cloud and precipitation. The amount of precipitation decreases both within the cloud and on the underlying surface. However, the lightning activity of the cloud changes little

Effects of High Aerosol Air Pollution on the Evolution of Convective Clouds during a Thunderstorm in China According to Three-dimensional Numerical Simulations

Effects of High Aerosol Air Pollution on the Evolution of Convective Clouds during a Thunderstorm in China According to Three-dimensional Numerical Simulations

Analyzing the Impact of Dust Emissions from Metallurgical Enterprises on the Environment

The metallurgical industry is an integral part of the Russian economy. Therefore, the improvement of technological processes at enterprises and the expansion of the raw material base by involving new deposits and production waste pose a significant threat to the environment. The city of Shelekhov is one of the most polluted cities not only in the Irkutsk Region, but also in Russia. Based on the results of a study of various literary sources, it has been found that Shelekhov is a city with a high level of air pollution and a high concentration of emissions per person per year, which makes the problem under consideration relevant. In our work, we used the methodology for calculating atmospheric air pollution, in which the duration of exposure to concentrations exceeding the established standards was used as a criterion for assessing atmospheric pollution. Based on the results of the calculations, it was confirmed that the concentration of pollutants in the form of aerosols in the atmospheric air for a long time exceeded the established average daily maximum allowable concentration. As a result of the calculations, we made a schematic map of the distribution of impurities from stationary sources in Shelekhov. This affects the general well-being of the city’s population, primarily among children and adolescents. Based on the studies concerning the disease incidence of the population, it was found that over time, the overall rate of illnesses in children only increases, and the most frequent diseases are respiratory ones.

Culturable Filamentous Fungi in the Air of Recreational Areas and Their Relationship with Bacteria and Air Pollutants during Winter

One of the greatest environmental health problems to arise in recent years is air pollution. Inorganic and organic particles are important components of air aerosol. The potential of air microbiota as an indicator of air quality is gaining increasing research interest. The aim of the present study was to determine the relationship between the level of fungal contamination and the levels of bacteria and smog particles in outdoor air in recreational areas during the heating season. A quantitative and qualitative mycological evaluation and quantitative bacteriological evaluation of air quality in 10 selected parks were performed. The numbers of microorganisms in the air were correlated with smog levels. The mean prevalence of fungi was 18.96 ± 15.43–23.30 ± 26.70 CFU/m3 of air and the mean bacterial count was 74.06 ± 130.89–268.04 ± 126.10 CFU/m3. Among the isolated fungi, clinically significant species were identified: four species belonged to Risk Group 2, and 17 to Risk Group 1. The predominant genera were Aspergillus, Penicillium and Alternaria. The total number of bacteria demonstrated a positive correlation with the size of the park, air temperature and ozone level during sampling, and a negative correlation with humidity, pressure and smog parameters (CO, NO, NO2 and NOx). The qualitative and quantitative composition of bioaerosols can be used as a bioindicator for environmental monitoring. There is a need for more efficient monitoring of airborne pollutants and microorganisms to learn about the structure of the air biota, the mechanisms regulating their occurrence, and to identify potential threats to human health.

Contribution of traffic-originated nanoparticle emissions to regional and local aerosol levels

Abstract. Sub-50 nm particles originating from traffic emissions pose risks to human health due to their high lung deposition efficiency and potentially harmful chemical composition. We present a modeling study using an updated European Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) number emission inventory, incorporating a more realistic, empirically justified particle size distribution (PSD) for sub-50 nm particles from road traffic as compared with the previous version. We present experimental PSDs and CO2 concentrations, measured in a highly trafficked street canyon in Helsinki, Finland, as an emission factor particle size distribution (EFPSD), which was then used in updating the EUCAARI inventory. We applied the updated inventory in a simulation using the regional chemical transport model PMCAMx-UF over Europe for May 2008. This was done to test the effect of updated emissions at regional and local scales, particularly in comparison with atmospheric new particle formation (NPF). Updating the inventory increased the simulated average total particle number concentrations by only 1 %, although the total particle number emissions were increased to a 3-fold level. The concentrations increased up to 11 % when only 1.3–3 nm sized particles (nanocluster aerosol, NCA) were considered. These values indicate that the effect of updating overall is insignificant at a regional scale during this photochemically active period. During this period, the fraction of the total particle number originating from atmospheric NPF processes was 91 %; thus, these simulations give a lower limit for the contribution of traffic to the aerosol levels. Nevertheless, the situation is different when examining the effect of the update closer spatially or temporally or when focusing on the chemical composition or the origin of the particles. For example, the daily average NCA concentrations increased by a factor of several hundred or thousand in some locations on certain days. Overall, the most significant effects – reaching several orders of magnitude – from updating the inventory are observed when examining specific particle sizes (especially 7–20 nm), particle components, and specific urban areas. While the model still has a tendency to predict more sub-50 nm particles compared to the observations, the most notable underestimations in the concentrations of sub-10 nm particles are now overcome. Additionally, the simulated distributions now agree better with the data observed at locations with high traffic densities. The findings of this study highlight the need to consider emissions, PSDs, and composition of sub-50 nm particles from road traffic in studies focusing on urban air quality. Updating this emission source brings the simulated aerosol levels, particularly in urban locations, closer to observations, which highlights its importance for calculations of human exposure to nanoparticles.

The impact of the aerosol reduction on the worsening ozone pollution over the Beijing-Tianjin-Hebei region via influencing photolysis rates

Due to the implementation of the toughest-ever emission control actions across China from 2013 to present, the aerosols are decreasing annually but ozone is simultaneously increasing, especially over the Beijing-Tianjin-Hebei (BTH) region, where ozone pollution can even spread into winter. Quantifying each impact of aerosols on ozone in all seasons is urgent for the worsening ozone pollution in the improved aerosol air quality. In this study, we focused on the impact of aerosols on ozone via influencing photolysis rates. The air pollutants were simulated over the Central East China (CEC) in 2018 by using the Weather Research and Forecasting with Chemistry (WRF-Chem) model. By implementing emissions with base years of 2014 and 2018, we quantified the increase in ozone (ΔOzone_photolysis) caused by the decreasing aerosol concentrations (ΔPM2.5) by influencing photolysis rates over the BTH region in all seasons. Furthermore, combined with the ozone observations, the contribution of ΔOzone_photolysis to the total changes in ozone (ΔOzone_total) in all seasons was quantitatively discussed. Our results showed that ΔPM2.5 showed obvious seasonal variations, which PM2.5 decreased more significantly in winter and autumn than in spring and summer, although significant reductions in anthropogenic emissions were observed in all seasons. Consistent seasonal variations were also observed in ΔOzone_photolysis, and the mean increases reached 5.5 μg m−3, 2.6 μg m−3, 1.2 μg m−3, and 1.4 μg m−3 in winter, autumn, spring, spring, and summer, respectively. Compared with ΔOzone_total, ΔOzone_photolysis accounted for 36.3%, 17.2%, 3.5% and 10.6% of ΔOzone_total in winter, autumn, spring, and summer, respectively, suggesting that ΔOzone_photolysis was not the primary contributor to the current changes in ozone over the BTH region. However, the 36.3% contribution to ΔOzone_total in winter suggested that ΔOzone_photolysis is still an important contributor and should not be ignored when discussing the formation of high ozone episodes occurring in winter.

On the Risk of Infection by Infectious Aerosols in Large Indoor Spaces

Airborne diseases can be transmitted by infectious aerosols in the near field, i.e., in close proximity, or in the far field, i.e., by infectious aerosols that are well mixed within the indoor air. Is it possible to say which mode of disease transmission is predominant in large indoor spaces? We addressed this question by measuring the transport of aerosols equivalent to the size of human respiratory particles in two large hardware stores (V > 10000 m3). We found that aerosol concentrations in both stores decreased rapidly and almost independently of aerosol size, despite the different ventilation systems. A persistent and directional airflow on the order of a few cm/s was observed in both stores. Consequently, aerosol dynamics in such open settings can be expected to be dominated by turbulent dispersion and sweeping flows, and the accumulation of infectious aerosols in the indoor air is unlikely to contribute significantly to the risk of infection as long as the occupancy of the store is not too high. Under these conditions, well-fitting face masks are an excellent means of preventing disease transmission by human aerosols.

Concentration and composition of cultured microorganisms in atmospheric air aerosols in Novosibirsk depending on the season

Concentration and composition of cultured microorganisms in atmospheric air aerosols in Novosibirsk depending on the season

Corrigendum to “Chemical Adsorption of Nitrogen Dioxide with an Activated Carbon Adsorption System” [Aerosol Air Qual. Res. 19: 2568-2575

The original version of this article omitted an affiliation for Chih-Hsiang Chen. The correct affiliations are listed below. Department of Finance, Ming Chuan University, Taipei 11103, TaiwanSchool of Software and Microelectronics, Peking University, Beijing 102600, China

Intrinsic background of the beta channel of the aerosol volumetric activity monitor

The work is devoted to the study of the features of generation of the intrinsic background of the measuring beta channel of the aerosol monitor in real conditions of measuring the volumetric activity of aerosols, caused by radionuclides of technogenic origin.&#x0D; The influence of external factors on the generation of the level of the intrinsic background of the measuring channel of the monitor and its metrological characteristics is investigated.&#x0D; The reliability of the results of measurements of the volumetric activity of air aerosols substantially depends on the correct accounting of external factors, parameters of the monitored environment and the specified operating mode of the monitor.&#x0D; Aerosol volumetric activity monitors, as a rule, operate in a continuous mode, in which the aspiration method of aerosol accumulation is implemented, followed by measuring the volumetric activity of aerosols by alpha radiation and (or) beta radiation generated by technogenic radionuclides.&#x0D; This article describes the results of experiments on measuring the iCAM aerosol monitor’s intrinsic beta channel background under real operating conditions, and its dependence on external factors.&#x0D; The studies were carried out on iCAM aerosol monitors (iCAM/D and iCAM/MF modifications) manufactured by Canberra Industries Inc. in a laboratory room in normal climatic conditions with a radon volumetric activity of 35±10 Bq·m-3 and an equivalent dose rate of gamma radiation of 0.13±0.02 μSv·h-1.&#x0D; In modern aerosol monitors, software and hardware solutions are implemented that allow to significantly reduce the background level and, as a result, to expand the measurement range of the volumetric activity of aerosols towards low values.