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1.
Environ Pollut ; 296: 118716, 2022 Mar 01.
Article in English | MEDLINE | ID: covidwho-1587842

ABSTRACT

The significant reduction in PM2.5 mass concentration after the outbreak of COVID-19 provided a unique opportunity further to study the formation mechanism of secondary inorganic aerosols. Hourly data of chemical components in PM2.5, gaseous pollutants, and meteorological data were obtained from January 1 to 23, 2020 (pre-lockdown) and January 24 to February 17, 2020 (COVID-lockdown) in Zhengzhou, China. Sulfate, nitrate, and ammonium were the main components of PM2.5 during both the pre-lockdown and COVID-lockdown periods. Compared with the pre-lockdown period, even though the concentration and proportion of nitrate decreased, nitrate was the dominant component in PM2.5 during the COVID-lockdown period. Moreover, nitrate production was enhanced by the elevated O3 concentration, which was favorable for the homogeneous and hydrolysis nitrate formation despite the drastic decrease of NO2. The proportion of sulfate during the COVID-lockdown period was higher than that before. Aqueous-phase reactions of H2O2 and transition metal (TMI) catalyzed oxidations were the major pathways for sulfate formation. During the COVID-lockdown period, TMI-catalyzed oxidation became the dominant pathway for aqueous-phase sulfate formation because the elevated acidity favored the dissolution of TMI. Therefore, the enhanced TMI-catalyzed oxidation affected by the elevated particle acidity dominated the sulfate formation, resulting in the slight increase of sulfate concentration during the COVID-lockdown period in Zhengzhou.


Subject(s)
Air Pollutants , COVID-19 , Aerosols/analysis , Air Pollutants/analysis , China , Communicable Disease Control , Environmental Monitoring , Humans , Hydrogen Peroxide , Pandemics , Particulate Matter/analysis , SARS-CoV-2 , Sulfates
2.
PLoS One ; 16(11): e0257689, 2021.
Article in English | MEDLINE | ID: covidwho-1518354

ABSTRACT

The worldwide spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has ubiquitously impacted many aspects of life. As vaccines continue to be manufactured and administered, limiting the spread of SARS-CoV-2 will rely more heavily on the early identification of contagious individuals occupying reopened and increasingly populated indoor environments. In this study, we investigated the utility of an impaction-based bioaerosol sampling system with multiple nucleic acid collection media. Heat-inactivated SARS-CoV-2 was utilized to perform bench-scale, short-range aerosol, and room-scale aerosol experiments. Through bench-scale experiments, AerosolSense Capture Media (ACM) and nylon flocked swabs were identified as the highest utility media. In room-scale aerosol experiments, consistent detection of aerosol SARS-CoV-2 was achieved at an estimated aerosol concentration equal to or greater than 0.089 genome copies per liter of room air (gc/L) when air was sampled for eight hours or more at less than one air change per hour (ACH). Shorter sampling periods (75 minutes) yielded consistent detection at ~31.8 gc/L of room air and intermittent detection down to ~0.318 gc/L at (at both 1 and 6 ACH). These results support further exploration in real-world testing scenarios and suggest the utility of indoor aerosol surveillance as an effective risk mitigation strategy in occupied buildings.


Subject(s)
Aerosols/analysis , COVID-19/diagnosis , COVID-19/virology , Environmental Monitoring , SARS-CoV-2/physiology , Genome, Viral , Humans , RNA, Viral/genetics , SARS-CoV-2/genetics
3.
Huan Jing Ke Xue ; 42(11): 5109-5121, 2021 Nov 08.
Article in Chinese | MEDLINE | ID: covidwho-1497977

ABSTRACT

To control the spread of the 2019 novel coronavirus(COVID-19), China imposed rigorous restrictions, which resulted in great reductions in pollutant emissions. However, two heavy haze pollution episodes still occurred in Beijing. In this study, we use the air pollutants, aerosol number concentration, and meteorological elements data in Beijing, combined with the HYSPLIT model, to calculate the potential source contribution factor(PSCF) and concentration weight trajectory(CWT), and analyze the characteristics of evolution and potential source apportionment of atmospheric pollutants during the two episodes. The COVID-19 lockdown restrictions had great impacts on the diurnal variations of PM2.5 and black carbon(BC), while small impacts on the diurnal variations of CO, NO2, SO2, and O3. The primary pollutant was PM2.5 during the two haze pollution episodes, and the haze1 episode was mainly local pollution, while haze 2 was mainly local and external transportation pollution. The spectrum of aerosol number concentration was unimodal under different processes, with the peak located at 0.3 µm. During the haze episodes, the number concentration in the size range of 0.2-0.5 µm increased 3.3-13.6 times that of the clean days. The mass concentration contributions of BCliquid to BC in different processes were 64.8%-85.1%. This mass concentration of BCliquid ranked in the order of haze 1(5.04 µg·m-3) >haze 1(3.20 µg·m-3) >clean day(before COVID-19) (2.31 µg·m-3) >clean day(COVID-19) (0.76 µg·m-3). The characteristics of PSCF and CWT distribution of PM2.5 and BC were different in different processes. The PSCF high value areas of PM2.5 on the clean day(before COVID-19) and the clean day(COVID-19) were mainly distributed in the southwest and western of Beijing, and the weight concentration exceeded 30 µg·m-3. The PSCF high value areas of PM2.5 during haze 1 and haze 2 were mainly distributed in Beijing and its surrounding areas and southwestern, when the weight concentration exceeded 90 µg·m-3. The PSCF high value areas of BC were mainly distributed in Beijing and its surrounding areas on clean days(before COVID-19), clean days(COVID-19) and haze 1, with weighted concentrations exceeding 2.4, 0.9 and, 4.5 µg·m-3, respectively. The PSCF high value areas of BC on haze 2 was distributed in the southwest of Beijing, and the weight concentration exceeded 5 µg·m-3.


Subject(s)
Air Pollutants , Air Pollution , COVID-19 , Environmental Pollutants , Aerosols/analysis , Air Pollutants/analysis , Air Pollution/analysis , Beijing , China , Communicable Disease Control , Environmental Monitoring , Humans , Particulate Matter/analysis , SARS-CoV-2 , Seasons
4.
Sci Rep ; 11(1): 20339, 2021 10 13.
Article in English | MEDLINE | ID: covidwho-1467132

ABSTRACT

This study investigated the environmental spatial heterogeneity of novel coronavirus (COVID-19) and spatial and temporal changes among the top-20 metropolitan cities of the Asia-Pacific. Remote sensing-based assessment is performed to analyze before and during the lockdown amid COVID-19 lockdown in the cities. Air pollution and mobility data of each city (Bangkok, Beijing, Busan, Dhaka, Delhi, Ho Chi Minh, Hong Kong, Karachi, Mumbai, Seoul, Shanghai, Singapore, Tokyo, Wuhan, and few others) have been collected and analyzed for 2019 and 2020. Results indicated that almost every city was impacted positively regarding environmental emissions and visible reduction were found in Aerosol Optical Depth (AOD), sulfur dioxide (SO2), carbon monoxide (CO), and nitrogen dioxide (NO2) concentrations before and during lockdown periods of 2020 as compared to those of 2019. The highest NO2 emission reduction (~ 50%) was recorded in Wuhan city during the lockdown of 2020. AOD was highest in Beijing and lowest in Colombo (< 10%). Overall, 90% movement was reduced till mid-April, 2020. A 98% reduction in mobility was recorded in Delhi, Seoul, and Wuhan. This analysis suggests that smart mobility and partial shutdown policies could be developed to reduce environmental pollutions in the region. Wuhan city is one of the benchmarks and can be replicated for the rest of the Asian cities wherever applicable.


Subject(s)
Air Pollution/prevention & control , COVID-19/epidemiology , Environmental Monitoring/methods , Aerosols/analysis , Air Pollutants/analysis , Air Pollution/analysis , Asia, Southeastern/epidemiology , Carbon Monoxide/analysis , Cities/epidemiology , Far East/epidemiology , Humans , Nitrogen Dioxide/analysis , Particulate Matter/analysis , Physical Distancing , SARS-CoV-2/pathogenicity , Sulfur Dioxide/analysis
6.
West J Emerg Med ; 22(5): 1045-1050, 2021 Aug 17.
Article in English | MEDLINE | ID: covidwho-1405508

ABSTRACT

INTRODUCTION: The coronavirus 2019 (COVID-19) pandemic has reinforced the importance of facial protection against droplet transmission of diseases. Healthcare workers wear personal protection equipment (PPE), including face shields and masks. Plastic face shields may have advantages over regular medical masks. Although many designs of face shields exist, there is a paucity of evidence regarding the efficacy of shield designs against droplet transmissions. There is even less published evidence comparing various face shields. Due to the urgency of the pandemic and the health and safety of healthcare workers, we aimed to study the efficacy of various face shields against droplet transmission. METHODS: We simulated droplet transmission via coughing using a heavy-duty chemical spray bottle filled with fluorescein. A standard-adult sized mannequin head was used. The mannequin head wore various face shields and was positioned to face the spray bottle at either a 0°, 45°, or 90° angle. The spray bottle was positioned at and sprayed from 30 centimeters (cm), 60 cm, or 90 cm away from the head. These steps were repeated for all face shields used. Control was a mannequin that wore no PPE. A basic mask was also tested. We collected data for particle count, total area of particle distribution, average particle size, and percentage area covered by particles. We analyzed percent covered by particles using a repeated measures mixed-model regression with Tukey-Kramer pairwise comparison. RESULTS: We used least square means to estimate the percentage area covered by particles. Wearing PPE regardless of the design reduced particle transmission to the mannequin compared to the control. The LCG mask had the lowest square means of 0.06 of all face-shield designs analyzed. Tukey-Kramer pairwise comparison showed that all PPEs had a decrease in particle contamination compared to the control. LCG shield was found to have the least contamination compared to all other masks (P < 0.05). CONCLUSION: Results suggest the importance of wearing a protective covering against droplet transmission. The LCG shield was found to decrease facial contamination by droplets the most of any tested protective equipment.


Subject(s)
Aerosols/analysis , COVID-19/prevention & control , Infection Control , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Inhalation Exposure/prevention & control , Masks/statistics & numerical data , Personal Protective Equipment/statistics & numerical data , COVID-19/epidemiology , Cough , Delivery of Health Care , Humans , Manikins , Masks/standards , Particle Size , Personal Protective Equipment/standards , SARS-CoV-2
7.
PLoS One ; 16(9): e0257137, 2021.
Article in English | MEDLINE | ID: covidwho-1394558

ABSTRACT

OBJECTIVES: High-speed tooth preparation requires effective cooling to avoid thermal damage, which generates spray mist, which is a mixture of an aerosol, droplets and particles of different sizes. The aim of this experimental study was to analyze the efficacy of spray mist reduction with an intraoral high-volume evacuation system (HVE) during simulated high-speed tooth preparation for suboptimal versus optimal suction positions of 16 mm sized cannulas and different flow rates of the HVE. MATERIAL AND METHODS: In a manikin head, the upper first premolar was prepared with a dental turbine, and generated particles of 5-50 microns were analyzed fifty millimeters above the mouth opening with the shadow imaging technique (frame: 6.6×5.3×1.1 mm). This setup was chosen to generate a reproducible spray mist in a vertical direction towards an imaginary operator head (worst case scenario). The flow rate (FR) of the HVE was categorized into five levels (≤120 l/min up to 330 l/min). The number of particles per second (NP; p/s) was counted, and the mass volume flow of particles per second (MVF; µg/s*cm3) was calculated for 10 sec. Statistical tests were nonparametric and two-sided (p≤0.05). RESULTS: With increasing flow rate, the NP/MVF values decreased significantly (eta: 0.671/0.678; p≤0.001). Using a suboptimally positioned cannula with an FR≤160 l/min, significantly higher NP values (mean±SD) of 731.67±54.24 p/s (p≤0.019) and an MVF of 3.72±0.42 µg/s*cm3 (p≤0.010) were measured compared to those of the optimal cannula position and FR≥300 l/min (NP/MVF: 0/0). No significant difference in NP and MVF was measurable between FR≥250 l/min and FR>300 l/min (p = 0.652, p = 0.664). CONCLUSION: Within the limitations of the current experimental study, intraoral high-flow rate suction with ≥300 l/min with an HVE effectively reduced 5-50 µm sized particles of the spray mist induced by high-speed tooth preparation with a dental turbine.


Subject(s)
Aerosols/analysis , Cannula , Humans , Rheology , Suction
8.
PLoS One ; 16(1): e0244983, 2021.
Article in English | MEDLINE | ID: covidwho-1388896

ABSTRACT

Here we look into the spread of aerosols indoors that may potentially carry viruses. Many viruses, including the novel SARS-CoV-2, are known to spread via airborne and air-dust pathways. From the literature data and our research on the propagation of fine aerosols, we simulate herein the carryover of viral aerosols in indoor air. We demonstrate that a lot of fine droplets released from an infected person's coughing, sneezing, or talking propagate very fast and for large distances indoors, as well as bend around obstacles, lift up and down over staircases, and so on. This study suggests equations to evaluate the concentration of those droplets, depending on time and distance from the source of infection. Estimates are given for the safe distance to the source of infection, and available methods for neutralizing viral aerosols indoors are considered.


Subject(s)
COVID-19/transmission , Disease Transmission, Infectious/prevention & control , Aerosols/analysis , Air Microbiology , Air Pollution, Indoor/analysis , COVID-19/metabolism , COVID-19/virology , Cough , Disease Transmission, Infectious/statistics & numerical data , Dust , Humans , Models, Theoretical , SARS-CoV-2/isolation & purification , Sneezing/physiology , Virus Diseases/prevention & control
10.
Int J Environ Res Public Health ; 18(7)2021 03 24.
Article in English | MEDLINE | ID: covidwho-1378221

ABSTRACT

Aerosol production represents a major concern during the majority of dental procedures. The aim of the present study is to investigate the dynamics of aerosol particles after 15 min of continuous supragingival ultrasonic instrumentation with no attempt of containment through particle count analysis. Eight volunteers were treated with supragingival ultrasonic instrumentation of the anterior buccal region. A gravimetric impactor was positioned 1 m away and at the same height of the head of the patient. Particles of different sizes (0.3-10 µm) were measured at the beginning of instrumentation, at the end of instrumentation (EI), and then every 15 min up to 105 min. The 0.3-µm particles showed non-significant increases at 15/30 min. The 0.5-1-µm particles increased at EI (p < 0.05), and 0.5 µm remained high for another 15 min. Overall, all submicron aerosol particles showed a slow decrease to normal values. Particles measuring 3-5 µm showed non-significant increases at EI. Particles measuring 10 µm did not show any increases but a continuous reduction (p < 0.001 versus 0.3 µm, p < 0.01 versus 0.5 µm, and p < 0.05 versus 1-3 µm). Aerosol particles behaved differently according to their dimensions. Submicron aerosols peaked after instrumentation and slowly decreased after the end of instrumentation, whilst larger particles did not show any significant increases. This experimental study produces a benchmark for the measurement of aerosol particles during dental procedures and raises some relevant concerns about indoor air quality after instrumentation.


Subject(s)
Air Pollution, Indoor , Particulate Matter , Aerosols/analysis , Air Pollution, Indoor/analysis , Environmental Monitoring , Humans , Particle Size , Ultrasonics
11.
Environ Sci Technol ; 55(17): 11557-11567, 2021 Sep 07.
Article in English | MEDLINE | ID: covidwho-1371582

ABSTRACT

The lockdown due to COVID-19 created a rare opportunity to examine the nonlinear responses of secondary aerosols, which are formed through atmospheric oxidation of gaseous precursors, to intensive precursor emission reductions. Based on unique observational data sets from six supersites in eastern China during 2019-2021, we found that the lockdown caused considerable decreases (32-61%) in different secondary aerosol components in the study region because of similar-degree precursor reductions. However, due to insufficient combustion-related volatile organic compound (VOC) reduction, odd oxygen (Ox = O3 + NO2) concentration, an indicator of the extent of photochemical processing, showed little change and did not promote more decreases in secondary aerosols. We also found that the Chinese provinces and international cities that experienced reduced Ox during the lockdown usually gained a greater simultaneous PM2.5 decrease than other provinces and cities with an increased Ox. Therefore, we argue that strict VOC control in winter, which has been largely ignored so far, is critical in future policies to mitigate winter haze more efficiently by reducing Ox simultaneously.


Subject(s)
Air Pollutants , Air Pollution , COVID-19 , Aerosols/analysis , Air Pollutants/analysis , Air Pollution/analysis , Air Pollution/prevention & control , China , Communicable Disease Control , Environmental Monitoring , Humans , Oxygen , Particulate Matter/analysis , SARS-CoV-2
12.
Huan Jing Ke Xue ; 42(9): 4116-4125, 2021 Sep 08.
Article in Chinese | MEDLINE | ID: covidwho-1368045

ABSTRACT

Organic carbon (OC), elemental carbon (EC), and PM2.5 concentration data obtained from Shanxi Super Station in Jiashan County of Jiaxing City, in the winter of 2018 and 2019, were analyzed to determine the variation and potential source areas of carbonaceous aerosols. The results show that OC concentrations in the winter of 2018 and 2019 were 6.90 µg·m-3 and 5.63 µg·m-3, respectively, while EC concentrations were 2.47 µg·m-3 and 1.57 µg·m-3, respectively. The concentrations of OC and EC in the winter of 2019 were lower than those in the winter of 2018, by approximately 18.4% and 36.4%, respectively. In 2018 and 2019, the concentrations of secondary organic carbon (SOC), calculated using the minimum R-squared (MRS) method, were 1.49 µg·m-3 and 1.97 µg·m-3, respectively, and the concentrations of primary organic carbon (POC) were 5.41 µg·m-3 and 3.66 µg·m-3, respectively. The proportion of POC in OC showed a downward trend, from 96.0% in December 2018 to 64.9% in February 2020, indicating a decrease of 31.1 percentage points. SOC showed an upward trend, increasing by 31.1 percentage points from 4.0% in December 2018 to 35.1% in February 2020. It is worth noting that with the increase in PM2.5 concentration, the concentration of OC and EC increased by 474.7% and 408.2%, respectively, although the proportion of OC in PM2.5 decreased from 18.8% to 12.3%. and the percentage of OC decreased from 5.8% to 3.3%. The contribution of POC to PM2.5 did not fluctuate, and only decreased significantly above 150 µg·m-3, while the contribution of SOC to PM2.5 first decreased and then increased. In Jiaxing, the potential sources of OC and EC were mainly southern Jiangsu, southeastern Anhui, local Jiaxing, and northern Zhejiang. In the winter of the contribution concentrations of OC and EC in the main potential source regions were approximately 2 µg·m-3 and 6 µg·m-3 lower, respectively, than in winter 2018. The range of high values in the potential source regions also decreased in 2019. Before the COVID-19 epidemic, it was affected by both motor vehicle exhaust emissions and coal burning. During the Spring Festival and home isolation, due to traffic control and other reasons, motor vehicle emissions were reduced, which leaving coal burning as the main contributor.


Subject(s)
Air Pollutants , COVID-19 , Aerosols/analysis , Air Pollutants/analysis , Environmental Monitoring , Humans , Particulate Matter/analysis , SARS-CoV-2
13.
Environ Res ; 203: 111788, 2022 01.
Article in English | MEDLINE | ID: covidwho-1330809

ABSTRACT

This work investigates the impact of COVID-19 restrictive measures on the mass concentrations of PM1 and PM10, and their chemical components (water-soluble ions, organic and elemental carbon, and major and trace metals) at an urban site in the western Mediterranean. The evolution of gaseous pollutants (NOx, O3 and some volatile organic compounds) was also analyzed. The concentrations measured during the lockdown in 2020 were compared to those obtained during the same period over the preceding five years. The average decrease in the levels of NOx and traffic-related volatile organic compounds was higher than 50 %, while O3 concentrations did not exhibit significant variations during the study period. Our results show that temporal variations in PM1 and PM10 concentrations were strongly affected by the frequency of Saharan dust events. When these episodes were excluded from the analysis period, a 35 % decrease in PM1 and PM10 levels was observed. Traffic restrictions during the lockdown led to important reductions in the concentrations of elemental carbon and metals derived from road dust (e.g. Ca and Fe) and break wear (e.g. Cu). Regarding secondary inorganic aerosols, nitrate showed the largest reductions as a consequence of the drop in local emissions of NOx.


Subject(s)
Air Pollutants , COVID-19 , Aerosols/analysis , Air Pollutants/analysis , Communicable Disease Control , Environmental Monitoring , Humans , Particulate Matter/analysis , SARS-CoV-2
14.
Environ Pollut ; 289: 117887, 2021 Nov 15.
Article in English | MEDLINE | ID: covidwho-1330804

ABSTRACT

The Chinese government issued an unprecedentedly strict lockdown policy to control the spread of the novel coronavirus disease 2019 (COVID-19), significantly mitigating air pollution because of the dramatic reduction of industrial and traffic emissions. To explore the impact of COVID-19 lockdown (LCD) on organic aerosols, the mixing states and evolution processes of amine-containing particles were studied using a single particle aerosol mass spectrometer from January to March 2020 in Liaocheng, which is a seriously polluted city in North China. The counts and percentages of amine-containing particles in total obtained particles during the pre-LCD (547832, 29.8 %) were higher than those during the LCD (283983, 20.7 %) and post-LCD (102026, 18.4 %), mainly due to the reduced emission strength of amines and suppressed gas-to-particle partitioning of amines during the LCD and post-LCD. 74(C2H5)2NH2+ was the most abundant amine marker, which accounted for 98.2 %, 98.4 %, and 96.7 % of all amine-containing particles during the pre-LCD, LCD, and post-LCD, respectively. Correlation analysis and temporal variations indicated that the gas-to-particle partitioning of amines was facilitated by the stronger acidic environment and lower temperature, while the effect of RH and aerosol liquid water content was minor. The A-OC particles were the most abundant type (accounting for ~40 %) throughout the observation period. The temporal profiles and correlation analysis suggested that the impact of the increased O3 on the amines and their oxidation products (e.g., trimethylamine oxide) was minor. The identified particle types, correlation analysis, and the potential source contribution function results implied that the amine-containing particles were mainly derived from local and surrounding sources during the LCD, while those were mainly affected by long-range transport during the pre-LCD and post-LCD. Our results could deepen the comprehension of the sources and atmospheric processing of amines in the urban area of North China during the COVID-19 outbreak.


Subject(s)
Air Pollutants , Air Pollution , COVID-19 , Aerosols/analysis , Air Pollutants/analysis , Air Pollution/analysis , Amines , Atmosphere , China , Communicable Disease Control , Disease Outbreaks , Environmental Monitoring , Humans , Particulate Matter/analysis , SARS-CoV-2
15.
Sci Rep ; 11(1): 15110, 2021 07 23.
Article in English | MEDLINE | ID: covidwho-1322504

ABSTRACT

The lockdown measures that were taken to combat the COVID-19 pandemic minimized anthropogenic activities and created natural laboratory conditions for studying air quality. Both observations and WRF-Chem simulations show a 20-50% reduction (compared to pre-lockdown and same period of previous year) in the concentrations of most aerosols and trace gases over Northwest India, the Indo Gangetic Plain (IGP), and the Northeast Indian regions. It is shown that this was mainly due to a 70-80% increase in the height of the boundary layer and the low emissions during lockdown. However, a 60-70% increase in the pollutants levels was observed over Central and South India including the Arabian sea and Bay of Bengal during this period, which is attributed to natural processes. Elevated (dust) aerosol layers are transported from the Middle East and Africa via long-range transport, and a decrease in the wind speed (20-40%) caused these aerosols to stagnate, enhancing the aerosol levels over Central and Southern India. A 40-60% increase in relative humidity further amplified aerosol concentrations. The results of this study suggest that besides emissions, natural processes including background meteorology and dynamics, play a crucial role in the pollution concentrations over the Indian sub-continent.


Subject(s)
Air Pollutants/analysis , Air Pollution/analysis , Environmental Monitoring/methods , Vehicle Emissions/analysis , Aerosols/analysis , Africa , Bays , COVID-19 , Communicable Disease Control , Correlation of Data , Dust/analysis , Environmental Pollution/analysis , Humans , India , Meteorology , Middle East , Oceans and Seas , Pandemics
16.
Sci Rep ; 11(1): 14477, 2021 07 14.
Article in English | MEDLINE | ID: covidwho-1310813

ABSTRACT

Air quality in urban areas and megacities is dependent on emissions, physicochemical process and atmospheric conditions in a complex manner. The impact on air quality metrics of the COVID-19 lockdown measures was evaluated during two periods in Athens, Greece. The first period involved stoppage of educational and recreational activities and the second severe restrictions to all but necessary transport and workplace activities. Fresh traffic emissions and their aerosol products in terms of ultrafine nuclei particles and nitrates showed the most significant reduction especially during the 2nd period (40-50%). Carbonaceous aerosol both from fossil fuel emissions and biomass burning, as well as aging ultrafine and accumulation mode particles showed an increase of 10-20% of average before showing a decline (5 to 30%). It is found that removal of small nuclei and Aitken modes increased growth rates and migration of condensable species to larger particles maintaining aerosol volume.


Subject(s)
Aerosols/analysis , Air Pollution/analysis , Nitrates/analysis , Particulate Matter/analysis , Vehicle Emissions/analysis , Aerosols/chemistry , Air Pollutants/analysis , COVID-19 , Environment , Environmental Monitoring , Greece , Humans , SARS-CoV-2 , Time Factors
17.
Biosens Bioelectron ; 192: 113499, 2021 Nov 15.
Article in English | MEDLINE | ID: covidwho-1309166

ABSTRACT

The recent outbreak of COVID-19 has highlighted the seriousness of airborne diseases and the need for a proper pathogen detection system. Compared to the ample amount of research on biological detection, work on integrated devices for air monitoring is rare. In this work, we integrated a wet-cyclone air sampler and a DC impedance microfluidic cytometer to build a cyclone-cytometer integrated air monitor (CCAM). The wet-cyclone air sampler sucks the air and concentrates the bioaerosols into 10 mL of aqueous solvent. After 5 min of air sampling, the bioaerosol-containing solution was conveyed to the microfluidic cytometer for detection. The device was tested with aerosolized microbeads, dust, and Escherichia coli (E. coli). CCAM is shown to differentiate particles from 0.96 to 2.95 µm with high accuracy. The wet cyclone air-sampler showed a 28.04% sampling efficiency, and the DC impedance cytometer showed 87.68% detection efficiency, giving a total of 24.59% overall CCAM efficiency. After validation of the device performance, CCAM was used to detect bacterial aerosols and their viability without any separate pretreatment step. Differentiation of dust, live E. coli, and dead E. coli was successfully performed by the addition of BacLight bacterial viability reagent in the sampling solvent. The usage could be further extended to detection of specific species with proper antibody fluorescent label. A promising strategy for aerosol detection is proposed through the constructive integration of a DC impedance microfluidic cytometer and a wet-cyclone air sampler.


Subject(s)
Biosensing Techniques , COVID-19 , Cyclonic Storms , Aerosols/analysis , Air Microbiology , Electric Impedance , Environmental Monitoring , Escherichia coli , Humans , Microfluidics , SARS-CoV-2
18.
Laryngoscope ; 131(12): 2759-2765, 2021 12.
Article in English | MEDLINE | ID: covidwho-1292540

ABSTRACT

OBJECTIVE: Severe acute respiratory syndrome coronavirus-2 spreads through respiratory fluids. We aim to quantify aerosolized particles during laryngology procedures to understand their potential for transmission of infectious aerosol-based diseases. STUDY DESIGN: Prospective quantification of aerosol generation. METHODS: Airborne particles (0.3-25 µm in diameter) were measured during live-patient laryngology surgeries using an optical particle counter positioned 60 cm from the oral cavity to the surgeon's left. Measurements taken during the procedures were compared to baseline concentrations recorded immediately before each procedure. Procedures included direct laryngoscopy with general endotracheal anesthesia (GETA), direct laryngoscopy with jet ventilation, and carbon dioxide (CO2 ) laser use with or without jet ventilation, all utilizing intermittent suction. RESULTS: Greater than 99% of measured particles were 0.3 to 1.0 µm in diameter. Compared to baseline, direct laryngoscopy was associated with a significant 6.71% increase in cumulative particles, primarily 0.3 to 1.0 µm particles (P < .0001). 1.0 to 25 µm particles significantly decreased (P < .001). Jet ventilation was not associated with a significant change in cumulative particles; when analyzing differential particle sizes, only 10 to 25 µm particles exhibited a significant increase compared to baseline (+42.40%, P = .002). Significant increases in cumulative particles were recorded during CO2 laser use (+14.70%, P < .0001), specifically in 0.3 to 2.5 µm particles. Overall, there was no difference when comparing CO2 laser use during jet ventilation versus GETA. CONCLUSIONS: CO2 laser use during laryngology surgery is associated with significant increases in airborne particles. Although direct laryngoscopy with GETA is associated with slight increases in particles, jet ventilation overall does not increase particle aerosolization. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:2759-2765, 2021.


Subject(s)
Air Microbiology , COVID-19/transmission , Laryngoscopy/adverse effects , Operating Rooms , SARS-CoV-2/isolation & purification , Aerosols/analysis , Anesthesia, Endotracheal/adverse effects , High-Frequency Jet Ventilation/adverse effects , Humans , Infectious Disease Transmission, Patient-to-Professional , Laryngoscopy/methods , Lasers, Gas/adverse effects , Prospective Studies , Suction/adverse effects
19.
Environ Pollut ; 286: 117577, 2021 Oct 01.
Article in English | MEDLINE | ID: covidwho-1275303

ABSTRACT

Revealing the changes in chemical compositions and sources of PM2.5 is important for understanding aerosol chemistry and emission control strategies. High time-resolved characterization of water-soluble inorganic ions, elements, organic carbon (OC), and elemental carbon (EC) in PM2.5 was conducted in a coastal city of southeast China during the COVID-19 pandemic. The results showed that the average concentration of PM2.5 during the city lockdown (CLD) decreased from 46.2 µg m-3 to 24.4 µg m-3, lower than the same period in 2019 (PM2.5: 37.1 µg m-3). Concentrations of other air pollutants, such as SO2, NO2, PM10, OC, EC, and BC, were also decreased by 27.3%-67.8% during the CLD, whereas O3 increased by 28.1%. Although SO2 decreased from 4.94 µg m-3to 1.59 µg m-3 during the CLD, the concentration of SO42- (6.63 µg m-3) was comparable to that (5.47 µg m-3) during the non-lockdown period, which were attributed to the increase (16.0%) of sulfate oxidation rate (SOR). Ox (O3+NO2) was positively correlated with SO42-, suggesting the impacts of photochemical oxidation. A good correlation (R2 = 0.557) of SO42- and Fe and Mn was found, indicating the transition-metal ion catalyzed oxidation. Based on positive matrix factorization (PMF) analysis, the contribution of secondary formation to PM2.5 increased during the epidemic period, consisting with the increase of secondary organic carbon (SOC), while other primary sources including traffic, dust, and industry significantly decreased by 9%, 8.5%, and 8%, respectively. This study highlighted the comprehensive and nonlinear response of chemical compositions and formation mechanisms of PM2.5 to anthropogenic emissions control under relatively clean conditions.


Subject(s)
Air Pollutants , COVID-19 , Aerosols/analysis , Air Pollutants/analysis , China , Communicable Disease Control , Environmental Monitoring , Humans , Pandemics , Particulate Matter/analysis , SARS-CoV-2 , Seasons , Sulfates , Vehicle Emissions/analysis
20.
Molecules ; 26(12)2021 Jun 08.
Article in English | MEDLINE | ID: covidwho-1264497

ABSTRACT

This paper presents a method of implementation and the results of aerosol dispersion tests in underground mine workings. Numerous tests were carried out to determine the potential risk of SARS-CoV-2 coronavirus infection in the underground environment of the mines. The influence of selected parameters of mine air on the possibility and method of aerosol transmission through ventilation routes was experimentally determined in real conditions. The concentration of additional aerosols in the class of ultrafine and fine aerosols increased with the distance from the generator, while the concentration of coarse particles decreased. Assuming the consumption of the solution with which aerosols were generated, even at a small level of 1 cm3/min., the number of additional aerosols was several hundred particles in one cubic centimeter of air at a distance of 50-70 m from the generator. The concentration of ultrafine particles in the range of 40-20,000 nm increased from 122 particles/cm3 to 209 particles/cm3 at air temperature of 12 °C and relative humidity of 95-96%, and from 90 particles/cm3 to 243 particles/cm3 at air temperature of 17 °C and relative humidity of 76-82%, with the increasing distance from the generator (10 m to 50 m).


Subject(s)
Aerosols/analysis , COVID-19/transmission , Coal Mining , Workplace/standards , Air/analysis , Environmental Monitoring/instrumentation , Environmental Monitoring/methods , Equipment Design , Humans , Occupational Exposure/analysis , Particle Size , Particulate Matter/analysis , Poland , SARS-CoV-2
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