Asian Journal of Atmospheric Environment最新文献

The role of aerosols in the spread of infectious diseases cannot be overemphasized in the face of increased environmental pollution from different sources. This study aimed at determining the distribution of fungi occurring in the air around human dwellings. The fungal aerosols were randomly collected from five crowded environments (market, church, school, motor park and crowded home) in Port Harcourt, Rivers State, Nigeria and examined. The sedimentation method was used for the microbiological sampling of air and fungi were identified based on macroscopic and microscopic method. The mean fungal load of the different crowded environments were as follows; market (3.19±0.43 log₁₀ SFU cm⁻² min⁻¹), church (2.96±0.33 log₁₀ SFU cm⁻² min⁻¹), school (3.22±0.29 log₁₀ SFU cm⁻² min⁻¹), motor park (3.25±0.35 log₁₀ SFU cm⁻² min⁻¹) and home (3.04±0.46 log₁₀ SFU cm⁻² min⁻¹), with motor park having the highest and church having the lowest. A total of 16 fungal isolates belonging to twelve (12) genera were identified. They included Aspergillus spp. (31.25%) and Paecilomyces sp., Mucor sp., Fusarium sp., Aspergillus sp., Rhizopus sp., Colletotrichum sp., Cryptococcus sp., Alternaria sp., Cladosporium sp., Chrysosporium sp. and Lophophyton sp. each having a percentage occurrence of 6.25%. Although there was no significant difference (p≥0.05) in the fungal population in the different sampled locations, Motor Park was observed to have the highest percentage occurrence (34.50%) and church the least (9.35%). The percentage occurrence from all sampled sites was in the order motor park>school>market>home>church. The presence of some potential pathogenic fungi such as Aspergillus flavus pose serious public health risks.

Heatwaves are acknowledged to be the major meteorological disaster, causing a noticeable impact on humans and animals’ lives during the last few decades. The number, frequency, duration, intensity, and areal extent of the heatwaves are on the rise during recent years. The Maximum temperature data of 2013 is analyzed to assess the synoptic nature, intensity, frequency, and various significant facets of the heatwave over the south peninsular states of Andhra Pradesh and Telangana. Indian subcontinent experienced a major heatwave during 2013, which claimed 1216 human lives. Even though the highest intensity of maximum temperatures is observed in May over major areas of India, the increasing (incidence, duration, number of spells, and the sweltering temperatures) number of heatwaves are observed over many parts of the country. The northwest and southeast coastal regions are the two heat wave prone regions. The advection of heat from the northwest with the aid of north-westerly winds causes heatwaves over northwest India to sweep or move towards India’s southeast and east coast. The heatwave record over south-eastern India, i.e, Andhra Pradesh and the adjoining Telangana state during May 22–24, 2013 were described in this study. Maximum temperatures above 40°C are observed with a sudden rise by 6 to 7°C over the study region. An attempt is made to predict the maximum temperatures 72 hours before the existence of a heatwave at 3 km horizontal resolution using the Advanced core of the Weather Research and Forecasting (WRF) model. Model predicted temperature values match with observations and the statistical metrics show a high index of the agreement, lower values for root-mean-square error and mean absolute error. Atmospheric circulation patterns associated with this heatwave are also presented. The arrest of sea breeze, the hovering of diabatic heat because of subsidence is the factor that abetted the heatwave blockade over the south-eastern part of the country. The WRF model forecasts could present the occurance of the heat wave over AP and Telangana region with 72 hour lead time with high accuracy.

Black Carbon (BC) is a major pollutant that poses immediate health as well as long-term climatic threat to human civilization. Globally, India and China are considered to be among the significant contributors of carbonaceous aerosol. Therefore, in the recent past, several studies on BC measurements have been conducted and reported in both these countries. Optical absorbance measurement techniques which give BC mass by measuring light absorbance of aerosol have been used widely. Keeping these facts in mind, here an attempt has been made to realise the current state of Equivalent Black Carbon (EBC) measurement done in both countries. Eighty EBC measurement studies published in last 15 years (2005–2020) are analysed on the basis of technique, instrumentation and various important parameters involved in measurements. It is found that EBC measurements in India and China contain large uncertainties, and available data are metrologically insufficient to realise spatial distribution and long-term temporal variation precisely. Furthermore, MERRA-2 Surface Black Carbon (SBC) levels and EBC measurements are compared and evaluated for biases between spatial and temporal variation of modelled data and ground measurements. It is observed that standardization of measurement technique and parameters involved in measurement is the need of the hour. Lack of a reference method creates inconsistency and discrepancy among the measurements. Recommendations for selection of parameter/instrument and cautious measures are provided as conclusion based on this review to improve overall metrology of BC.

Real-time onsite monitoring of indoor airborne microbes in a residential property in central Tokyo was carried out in 2020 and 2021, following the onset of the COVID-19 pandemic. A microbial sensor utilizing fluorescence emitted by microorganisms was used to measure bioaerosol concentrations in the living room and children’s bedroom as well as on the balcony. Indoor PM_2.5 was also monitored simultaneously at certain time points using a PM_2.5 sensor. The behavior of the residents was also recorded during some monitoring periods. The average number concentration of microbes as fungi in the living room was 15,100, 58,800, and 10,600 counts m⁻³ in spring, summer, and winter, respectively, increasing in summer when the outside temperature was high. Microbial number concentrations were closely related to human behavior, increasing rapidly during periods of physical activity, but decreasing again within 20–30 min of the activity ending. There was no clear correlation between indoor microbial number concentrations and PM_2.5 concentrations, suggesting that indoor microorganisms are concentrated in coarse particles, such as dust, which are quickly removed via gravitational settling. The concentration of indoor airborne microorganisms decreased significantly after ventilation, and although an occasional increase was observed immediately after ventilation, concentrations decreased again rapidly within 10–20 min. These results suggest that even a short period of ventilation can significantly reduce the indoor bioaerosol.

Total Column Ozone (TCO) is a critical factor affecting the earth’s atmosphere, especially in the Himalayan region. A comprehensive study of TCO trend analysis and corresponding consequences in the Himalayan atmosphere needs to be analyzed. We statistically examine TCO variability by analyzing the daily TCO dataset of the last 15 years (2005–2019) over the crucial region of the Himalayan environment i.e. Uttara-khand, India. Obtained results indicate that TCO values are at peak during the spring season whereas it shows the least value during the winter season. The highest and lowest value of Coefficient of Relative Variance (CRV) is estimated as 3.14 and 1.09 during winter and monsoon season, respectively. Air mass trajectories have been estimated using Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT), which shows the existence of strong seasonal variability of Ozone corresponding to continental and maritime transportation towards Uttarakhand. Moreover, Least Square Method (LSM) and the Mann-Kendall test estimate a high correlation (86%) for the seasonal and annual trend of TCO with a negative rate. The obtained decreasing rate is very low which indicates recovery of TCO during the study period. Further results imply that the inter-annual oscillation pattern of TCO is similar to Quasi-Biennial Oscillation (QBO) significantly. In addition, a comparative study has been performed for the data measured by two TCO measuring instruments i.e. Ozone Monitoring Instrument (OMI) and Ozone Mapping Profiler Suite (OMPS). TCO values measured from both instruments are highly correlated (96%) with an average relative difference of around 3%. The outcomes of this study are expected to be beneficial for future study of TCO over other crucial regions of Himalayan territory.

A high concentration of volatile organic compounds (VOCs) is emitted during dry cleaning processes. Although carbonaceous materials have been widely tested for the control of VOC emission, there is a risk of fire when a large amount of VOCs is contained. Non-carbon adsorbents such as KIT-6, SBA-15, MCM-41, X-type zeolites, Y-type zeolites, aluminum silicate, and activated alumina are therefore tested in this study for the adsorption and desorption of decane which is a main constituent of VOCs emitted during dry cleaning. The adsorbents were evaluated under two conditions with and without the injection of water vapor (20% rh) using a fixed-bed reactor system. Without the injection of water vapor, KIT-6 showed the highest decane adsorption capacity, and activated alumina showed the highest decane desorption efficiency. It was also found that the mesopore volume of the adsorbent was related to its decane adsorption capacity, whereas its peak pore diameter was closely related to its decane desorption efficiency. KIT-6 showed very similar decane adsorption and desorption performance in both cases with and without the injection of water vapor. However, the decane desorp-tion efficiency of activated alumina significantly decreased with the injection of water vapor.

Continuous monitoring of hourly PM_2.5 component concentrations has been performed in Japan. The objective of this study was to evaluate the advantages of continuous monitoring to obtain data that can be useful for regional air quality simulations. Inclusion of transboundary transport in the simulations improved the correlation between the observed and simulated hourly concentrations of SO₄²⁻, SO₃⁻, secondary organic aerosols (SOA), and metals in PM_2.5. Black carbon was an exception, suggesting the overestimation of emissions in upwind countries. Including volcanic and dust emissions also improved the correlations between the observed and simulated hourly concentrations of SO₄²⁻ and metals, respectively. However, despite the good correlation achieved by including transboundary transport, it also resulted in overestimated NO₃²⁻ and SOA concentrations in western Japan during the winter. Further improvements are necessary, such as balancing with SO₄²⁻ and the dry deposition of gaseous HNO₃ for NO₃⁻, and new treatment of the partitioning and aging of semivolatile organic aerosols, which have been incorporated into recent models for SOA. The differences in model performance with regard to simulating metal concentrations suggest imbalances in the speciation profiles used for countries other than Japan. Further, comparing the observed and simulated hourly concentrations helped identify the key processes driving air quality. This revealed evening peaks in black carbon concentrations, owing to the relatively stable atmosphere; and early morning peaks in NO₃⁻ concentration, owing to the low temperature and high humidity through thermodynamic equilibrium. This study demonstrated that continuous monitoring of hourly variations in PM_2.5 composition is valuable for understanding the roles of the emission sources and for improving future models, both of which contribute to deriving effective PM_2.5 suppression strategies.

This study investigates the importance of using engineering ventilation in healthcare settings, especially during widespread disease outbreaks such as COVID-19. Ventilation can be used to improve indoor air quality in care homes, hospitals, and quarantine locations. In the research, two scenarios of engineering ventilation are simulated using a Fire Dynamic Simulator (FDS), with sulfur hexafluoride employed as the contaminant emitted by the patient in the hospital room. The volume of the room selected for the present study is 60 m³, and the ventilation mode is designed according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), with 12 air changes per hour and negative pressure. The mean concentration of the pollutants is estimated for both scenarios, giving concentrations in the range of 920±397 to 1260±580 ppm. The estimated indoor air quality (IAQ) values varied from 2.06 to 2.90. According to the obtained results, ventilation plays a critical role in eliminating pollutants, indicating that suitably engineered ventilation strategies can reduce the impact of COVID-19 spread in closed buildings.

Concentrations of black carbon (BC), organic carbon (OC), and total suspended particulate matter (TSP) were simultaneously assessed in urban, rural and residential areas in Jeddah city for one year from January to December 2017. It was aimed in the present study to provide information about the spatial and seasonal variability of these aerosol species in Jeddah, and insight into sources, processes and effects of meteorological conditions. To the best of our knowledge, this is the first study investigating the variability of carbonaceous aerosols (OC and BC) in Saudi Arabia. The average concentrations of OC, BC, and TSP varied spatially and temporally. The annual average concentrations of OC, BC, and TSP were 134.05, 7.16, and 569.41 μg m⁻³ and 34.32, 5.14, and 240.64 μg m⁻³ and 10.67, 4.39 and 101.31 μg m⁻³ in the urban, residential and rural areas, respectively. Moreover, there was a clear seasonal variation in the concentration of carbonaceous aerosols; the highest concentrations were recorded in February and September, while the lowest concentrations of OC were recorded during April, May and August in the urban, residential and rural sites, respectively. Nevertheless, the lowest concentrations of BC were recorded during March in the urban and residential sites and during November in the rural site. The relative concentrations of OC and BC to the TSP were relatively high, and they have a significant correlation with prevalent wind speed (−0.636, and −0.581 in the urban area), (−0.539 and −0.511 in the residential area), and (−0.508 and −0.501 in the rural area), respectively. The marked differences in the concentrations of BC and OC were reflected on OC/BC ratio, which is a good representative of different source types. This preliminary study showed that the potential local sources were emissions from traffic (fossil fuel), biomass burning, anthropogenic activities (e.g. car drifting and outdoor cooking), and industrial activities. The present study suggest the presence of highly inefficient combustion sources and highlight the need for the regulation of such emissions.

Stable isotope ratios (δ²H and δ¹⁸O), tritium (³H). and deuterium excess (d-excess) values of atmospheric precipitation (P) at 16 stations were determined for mapping the spatial variation of oxygen and hydrogen P isotopes in Syria. The major geographical parameters (longitude east, LE; latitude north, LN; altitude, H; and inland distance from the coast, DFC) were used to find out the best fitting models for the spatial mapping of atmospheric P isotopes in Syria. The highest correlation coefficients (r>0.73) were found for the relationships δ¹⁸O-H and δ²H-H. The impacts of LE and LN factors were rather moderate (0.3<r<0.6). However, a high correlation coefficient (r>0.7) was found for the relationship d-excess-LN. The increase of d-excess value from 23‰ to 24‰ in southern Syria is due to the Mediterranean Sea (MS) moisture, likely as a high percentage (>65%) of prevailed winds usually comes over the MS. The concentrations of ³H in P samples(4-14TU) during the period 1989–1993 were higher than those (3-10TU) for the period 2004–2006, indicating thus a return back toward the levels of typical ³H production in nature. The high correlation coefficients (r>0.59) that were found for the relationships ³H-DFC and ³H-LE, suggest a continuous exchange between the low tritium moisture from the MS and the higher tritium moisture from the inland areas. Produced gridded isotopic values are quite satisfactory for covering certain areas in Syria and the neighboring Arab countries.