scholarly journals Seasonal variation in airborne infection risk in schools due to changes in ventilation inferred from monitored carbon dioxide

Indoor Air ◽  
2021 ◽  
Author(s):  
Carolanne V. M. Vouriot ◽  
Henry C. Burridge ◽  
Catherine J. Noakes ◽  
Paul F. Linden
Keyword(s):  
Carbon Dioxide ◽  
Seasonal Variation ◽  
Infection Risk ◽  
Airborne Infection

scholarly journals Predictive and retrospective modelling of airborne infection risk using monitored carbon dioxide

2021 ◽  
pp. 1420326X2110435
Author(s):  
Henry C. Burridge ◽  
Shiwei Fan ◽  
Roderic L. Jones ◽  
Catherine J. Noakes ◽  
P. F. Linden
Keyword(s):  
Carbon Dioxide ◽  
Absolute Risk ◽  
Infection Risk ◽  
Expected Number ◽  
Indoor Space ◽  
Airborne Infection ◽  
Secondary Infections ◽  
School Classroom ◽  
Open Plan ◽  
Ventilation Rates

The risk of long range, herein ‘airborne', infection needs to be better understood and is especially urgent during the COVID-19 pandemic. We present a method to determine the relative risk of airborne transmission that can be readily deployed with either modelled or monitored CO2 data and occupancy levels within an indoor space. For spaces regularly, or consistently, occupied by the same group of people, e.g. an open-plan office or a school classroom, we establish protocols to assess the absolute risk of airborne infection of this regular attendance at work or school. We present a methodology to easily calculate the expected number of secondary infections arising from a regular attendee becoming infectious and remaining pre/asymptomatic within these spaces. We demonstrate our model by calculating risks for both a modelled open-plan office and by using monitored data recorded within a small naturally ventilated office. In addition, by inferring ventilation rates from monitored CO2, we show that estimates of airborne infection can be accurately reconstructed, thereby offering scope for more informed retrospective modelling should outbreaks occur in spaces where CO2 is monitored. Well-ventilated spaces appear unlikely to contribute significantly to airborne infection. However, even moderate changes to the conditions within the office, or new variants of the disease, typically result in more troubling predictions.

Diurnal and seasonal variation of carbon dioxide exchange from a former true raised bog

1998 ◽  
Vol 4 (8) ◽  
pp. 823-833 ◽  
Author(s):  
JOOST P. NIEVEEN ◽  
COR. M. J. JACOBS ◽  
ADRIE F. G. JACOBS
Keyword(s):  
Carbon Dioxide ◽  
Seasonal Variation ◽  
Carbon Dioxide Exchange ◽  
Raised Bog

scholarly journals Variability of dissolved CO<sub>2</sub> in the Pang and Lambourn Chalk rivers

2007 ◽  
Vol 11 (1) ◽  
pp. 328-339 ◽  
Author(s):  
J. Griffiths ◽  
J. Nutter ◽  
A. Binley ◽  
N. Crook ◽  
A. Young ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Seasonal Variation ◽  
Surface Waters ◽  
Temporal Variability ◽  
Stream Water ◽  
Spatial And Temporal Variability ◽  
Dissolved Carbon ◽  
Dissolved Carbon Dioxide ◽  
Borehole Water ◽  
Carbon Dioxide Co2

Abstract. This paper presents the results of a two-year field campaign to determine the spatial and temporal variability of groundwater interaction with surface waters in two Cretaceous Chalk catchments (the Pang and Lambourn) in the Upper Thames in Berkshire, UK, based on measurement of dissolved carbon dioxide (CO2). Average stream water concentrations of dissolved CO2 were up to 35 times the concentration at atmospheric equilibrium. Mean groundwater concentrations of 85 and 70 times the atmospheric equilibrium were determined from borehole water sampled in the Pang and Lambourn respectively. Diurnal and seasonal variation of in-stream concentration of dissolved CO2 is not significant enough to mask the signal from groundwater inputs.

scholarly journals Simulation-Based Study on the COVID-19 Airborne Transmission in a Restaurant

2020 ◽  
Author(s):  
Han Liu ◽  
Sida He ◽  
Lian Shen ◽  
Jiarong Hong
Keyword(s):  
Preventive Measures ◽  
Strong Support ◽  
Infection Risk ◽  
Exposure Index ◽  
Reverse Time ◽  
Aerosol Transport ◽  
Airborne Transmission ◽  
Local Flow ◽  
Airborne Infection ◽  
Aerosol Exposure

COVID-19 has shown a high potential of transmission via virus-carrying aerosols as supported by growing evidence. However, detailed investigations that draw direct links between aerosol transport and virus infection are still lacking. To fill in the gap, we conducted a systematic computational fluid dynamics (CFD)-based investigation of indoor air flow and the associated aerosol transport in a restaurant setting, where likely cases of airborne infection of COVID-19 caused by asymptomatic individuals were widely reported by the media. We employed an advanced in-house large eddy simulation (LES) solver and other cutting-edge numerical methods to resolve complex indoor processes simultaneously, including turbulence, flow–aerosol interplay, thermal effect, and the filtration effect by air conditioners. Using the aerosol exposure index derived from the simulation, we are able to provide a spatial map of the airborne infection risk under different settings. Our results have shown a remarkable direct linkage between regions of high aerosol exposure index and the reported infection patterns in the restaurant, providing strong support to the airborne transmission occurring in this widely-reported incidence. Using flow structure analysis and reverse-time tracing of aerosol trajectories, we are able to further pinpoint the influence of environmental parameters on the infection risks and highlight the needs for more effective preventive measures, e.g., placement of shielding according to the local flow patterns. Our research, thus, has demonstrated the capability and value of high-fidelity CFD tools for airborne infection risk assessment and the development of effective preventive measures.

scholarly journals Seasonal variation in ecosystem parameters derived from FLUXNET data

2009 ◽  
Vol 6 (2) ◽  
pp. 2863-2912 ◽  
Author(s):  
M. Groenendijk ◽  
M. K. van der Molen ◽  
A. J. Dolman
Keyword(s):  
Carbon Dioxide ◽  
Seasonal Variation ◽  
Ecosystem Respiration ◽  
Vegetation Type ◽  
Correlation Coefficients ◽  
Carbon Dioxide Flux ◽  
Model Parameters ◽  
Flux Data ◽  
Quality Checks ◽  
Parameter Values

Abstract. The carbon dioxide sink is in a complex way related to weather and climate. In order to better understand the relationship and feedbacks, we present a methodology to simulate observed carbon dioxide flux data with a simple vegetation model (5PM) with weekly varying model parameters. The model parameters explain the interaction between vegetation and seasonal climate more general than the flux data. Two parameters (Rref and E0) are related to ecosystem respiration and three parameters (Jm, α and λ) to photosynthesis and transpiration. We quantified the weekly variability of ecosystem parameters as a function of vegetation type and climate region. After statistical quality checks 121 FLUXNET sites were available for analysis of the weekly varying model parameters. The simulations of these sites have high correlation coefficients (r2=0.6 to 0.8) between the observed and simulated carbon and water fluxes. With weekly parameters we determined average seasonal cycles for the different combinations of vegetation type and climate regions (PFTs). The variation between PFTs is large, which provides an excellent dataset to study the differences in ecosystem characteristics. In general we observed that needleleaf forests and grasslands in warmer climates have relatively constant parameter values during the year. Broadleaf forests in all climate regions have large seasonal variation for each of the five parameters. In boreal regions parameter values are always lower than in temperate regions. A large seasonality of the model parameters indicates a strong relation between vegetation and climate. This suggests that climate change will have the largest impact on the terrestrial carbon fluxes in boreal regions and for deciduous forests, and less for grasslands and evergreen forests.

Increased RBC Count and Pulmonary Respiration in Cold-Adapted Frogs

1974 ◽  
Vol 61 (2) ◽  
pp. 285-290
Author(s):  
R. V. KRISHNAMOORTHY ◽  
N. SHAKUNTHALA
Keyword(s):  
Carbon Dioxide ◽  
Seasonal Variation ◽  
Oxygen Saturation ◽  
Cold Acclimation ◽  
Carbon Dioxide Content ◽  
Cold Adapted ◽  
Respiratory Parameters ◽  
Haemoglobin Content ◽  
Pulmonary Respiration ◽  
Rbc Count

1. Haematological and respiratory parameters (including RBC count, CO2 content and percentage oxygen saturation) were studied in cold-acclimated (12 ± 1 °C) and normal frogs (23 ± 2 °C). 2. Seasonal variation in RBC count was found, the count being higher in January than in September. Females showed higher counts than males. Cold-acclimation resulted in the elevation of counts in all seasons and in both sexes, and was accompanied by a rise in haemoglobin content. 3. Cold-acclimated frogs retained a higher oxygen saturation in the truncus arteriosus than in the cutaneous vein, the carbon dioxide content of the truncus being also reduced in acclimated frogs. The O2/CO2 ratios were thus higher in the truncus than in the cutaneous vein. 4. Cold-acclimated frogs released more 14CO2 through the lungs. 5. It is suggested that a change in the mode of respiration occurs when the frogs are acclimated to cold.

Airborne infection risk during open-air cardiopulmonary resuscitation

2021 ◽  
pp. emermed-2021-211209
Author(s):  
Talib Dbouk ◽  
Silvia Aranda-García ◽  
Roberto Barcala-Furelos ◽  
Antonio Rodríguez-Núñez ◽  
Dimitris Drikakis
Keyword(s):  
Fluid Dynamics ◽  
Wind Speed ◽  
Relative Humidity ◽  
Cardiopulmonary Resuscitation ◽  
Three Dimensional ◽  
Virus Transmission ◽  
Infection Risk ◽  
Dynamics Simulation ◽  
Airborne Infection ◽  
Air Index

AimCardiopulmonary resuscitation (CPR) is an emergency procedure where interpersonal distance cannot be maintained. There are and will always be outbreaks of infection from airborne diseases. Our objective was to assess the potential risk of airborne virus transmission during CPR in open-air conditions.MethodsWe performed advanced high-fidelity three-dimensional modelling and simulations to predict airborne transmission during out-of-hospital hands-only CPR. The computational model considers complex fluid dynamics and heat transfer phenomena such as aerosol evaporation, breakup, coalescence, turbulence, and local interactions between the aerosol and the surrounding fluid. Furthermore, we incorporated the effects of the wind speed/direction, the air temperature and relative humidity on the transport of contaminated saliva particles emitted from a victim during a resuscitation process based on an Airborne Infection Risk (AIR) Index.ResultsThe results reveal low-risk conditions that include wind direction and high relative humidity and temperature. High-risk situations include wind directed to the rescuer, low humidity and temperature. Combinations of other conditions have an intermediate AIR Index and risk for the rescue team.ConclusionsThe fluid dynamics, simulation-based AIR Index provides a classification of the risk of contagion by victim’s aerosol in the case of hands-only CPR considering environmental factors such as wind speed and direction, relative humidity and temperature. Therefore, we recommend that rescuers perform a quick assessment of their airborne infectious risk before starting CPR in the open air and positioning themselves to avoid wind directed to their faces.

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