The role of airborne transmission in a large single source outbreak of SARS-CoV-2 in a Belgian nursing home in 2020

Objectives: To better understand the conditions which have led to one of the largest COVID-19 outbreaks in Belgian nursing homes in 2020. Setting: A nursing home in Flanders, Belgium, which experienced a massive outbreak of COVID-19 after a cultural event. An external volunteer who dressed as a legendary figure visited consecutively the 4 living units and tested positive for SARS-CoV-2 the next day. Within days, residents started to display symptoms and the outbreak spread rapidly within the nursing home. Methods: We interviewed key informants and collected standardized data from all residents retrospectively. A batch of 115 positive samples with a Ct value of <37 by qRT-PCR were analysed using whole-genome sequencing. Six months after the outbreak, ventilation assessment of gathering rooms in the nursing home was done using a tracer gas test with calibrated CO2 sensors. Results: Timeline of diagnoses and symptom onsets clearly pointed to the cultural event as the start of the outbreak, with the volunteer as index case. The genotyping of positive samples depicted the presence of one large cluster, suggesting a single source outbreak. The global attack rate among residents was 77% with a significant association between infection and presence at the event. Known risk factors such as short distance to or physical contact with the volunteer, and wearing of a mask during the event were not associated with early infection. The ventilation assessment showed a high background average CO2 level in four main rooms varying from 657 ppm to 846 ppm. Conclusions: Our investigation shows a rapid and widespread single source outbreak of SARS-CoV-2 in a nursing home, in which airborne transmission was the most plausible explanation for the massive intra-facility spread. Our results underscore the importance of ventilation and air quality for the prevention of future outbreaks in closed facilities.

Carbonic Anhydrase as CO2 capturing agent: its Classes and Catalytic Mechanisms

Carbonic anhydrase (CA; EC 4.2.4.1), metalloenzyme, can catalyze reversible hydration of CO2 (CO2 + H2O ↔ H+ + HCO3 -) with high efficiency (kcat ~106 s-1) and plays fundamental roles in many biological processes like photosynthesis, respiration, pH homeostasis and ion transport. Recently, CA has been considered as an important biocatalyst for CO2 sequestration technology because the accumulation of CO2 is the main cause for global climate change and it is critical to develop technologies that can reduce atmospheric CO2 level. This review deals with the classes and mechanisms of several CAs as CO2 capture agents

Development of Sustainable Indoor Air Quality for Air-Conditioning System Using Smart Control Techniques

Air-conditioning as a technical solution to protect inhabitants from excessive heat exposure creates the challenge of expanding indoor health effects. While air-conditioning has mostly been applied as an improvement to living conditions, health and environmental problems associated with its use frequently occurs. Therefore, this paper challenges and extends existing knowledge on sustainability related to the smart air-conditioning systems. The decrease of CO2 level in building requires an intelligent control system because energy utilisation has been legitimately connected with wellbeing and eventually to operational expenses. A building’s indoor environmental essential factors of comfort are IAQ, visual and thermal. Through an appropriate structured controller, the performance of indoor control system can be altogether improved. It merits creating innovative control techniques to optimise the indoor environment quality for air-conditioning system. The newly proposed backpropagation neural network was optimised using Matlab to control the CO2 level appropriately while carefully taking into account the performance of system controllers such as the stability, adaptability, speed response and overshoot. The controller of indoor environment was designed, and the proportional-integral-derivative control was utilised as a result of its suitability. The smart controllers were designed to regulate the parameters automatically to ensure the optimised control output. The indoor CO2 possesses an appropriate time constant and settling time of 2.1s and 27.3s, respectively. Therefore, utilising smart control techniques to exterminate various indoor health effects is expected to produce sustainable living conditions.

The Importance of Precursors and Modification Groups of Aerogels in CO2 Capture

The rapid growth of CO2 emissions in the atmosphere has attracted great attention due to the influence of the greenhouse effect. Aerogels’ application for capturing CO2 is quite promising owing to their numerous advantages, such as high porosity (~95%); these are predominantly mesoporous (20–50 nm) materials with very high surface area (>800 m2∙g−1). To increase the CO2 level of aerogels’ uptake capacity and selectivity, active materials have been investigated, such as potassium carbonate, K2CO3, amines, and ionic-liquid amino-acid moieties loaded onto the surface of aerogels. The flexibility of the composition and surface chemistry of aerogels can be modified intentionally—indeed, manipulated—for CO2 capture. Up to now, most research has focused mainly on the synthesis of amine-modified silica aerogels and the evaluation of their CO2-sorption properties. However, there is no comprehensive study focusing on the effect of different types of aerogels and modification groups on the adsorption of CO2. In this review, we present, in broad terms, the use of different precursors, as well as modification of synthesis parameters. The present review aims to consider which kind of precursors and modification groups can serve as potentially attractive molecular-design characteristics in promising materials for capturing CO2.

Impact of Climate Change on Agriculture and Food Security: A Review

Climate change has emerged as a major man-made global environmental problem, characterized by an increase in the earth's air temperature as a result of large-scale emissions of greenhouse gases. Agriculture and climate change are intrinsically linked in different ways, since biotic and abiotic stresses are primarily caused by climate change, all these factors have a detrimental effect on a region's agriculture. Agriculture is affected by climate change in various ways, e.g., heat stress at the reproductive stage, shortening of growing season length, pests or microbes, modification in weeds, and increase in CO2 level. The challenge of changing global climate has driven the scientists' interest, As a result of these changes, global crop production is suffering and global food security is in danger. The current study sheds light on the impacts of climate change on agriculture, as well as the consequences for food security.

Past terrestrial hydroclimate driven by Earth System Feedbacks

Geologic evidence suggests drastic reorganizations of subtropical terrestrial hydroclimate during past warm intervals, including the mid-Piacenzian Warm Period (MP, 3.3 to 3.0 Ma). Despite having a similar to present-day atmospheric CO2 level (pCO2), MP featured moist subtropical conditions with high lake levels in Northern Africa, and mesic vegetation and sedimentary facies in subtropical Eurasia. Here, we demonstrate that major loss of the northern high-latitude ice sheets and continental greening, not the pCO2 forcing, are key to generating moist terrestrial conditions in subtropical Sahel and east Asia. In contrast to previous hypotheses, the moist conditions simulated in both regions are a product of enhanced tropospheric humidity and a stationary wave response to the surface warming pattern, both varying strongly in response to land cover changes. These results suggest that past terrestrial hydroclimate states were driven by Earth System Feedbacks, which may outweigh the direct effect of pCO2 forcing.

Assessment of Air Quality Perception and Its Effects on Users’ Thermal Comfort in Office Buildings

Since people spend most of their time in indoor environments, the objective of this work was to study indoor air quality perception and its effects on users&rsquo; thermal comfort. Based on previous data from a building with a central air-conditioning system and two mixed-mode buildings located in the humid subtropical climate of Florian&oacute;polis, southern Brazil, statistical analyses were performed. Each user subjective answer obtained through a questionnaire was combined with the corresponding environmental conditions &ndash; measured using microclimate stations, a portable thermo-anemometer and a CO2 analyser. Results showed that improvement in air quality was associated with the reduction of air temperature and humidity ratio. Also, there was a significant influence of thermal, air movement and humidity sensation and acceptability of air quality perception. Users felt more satisfied or neutral with air quality for being in thermal comfort, and not because of the CO2 level &ndash; which means that air quality perception is influenced by factors other than CO2. This study recommends the implementation of an air exchange device in split air-conditioners with air recirculation used in mixed-mode buildings in Brazil. It is important to provide suitable indoor ventilation to reduce pollutants concentration, ensure good air quality and prevent respiratory diseases.