A multi-layered strategy for COVID-19 infection prophylaxis in schools: A review of the evidence for masks, distancing, and ventilation.

Implications for the academic and interpersonal development of children and adolescents underpin a global political consensus to maintain in-classroom teaching during the ongoing COVID-19 pandemic. In support of this aim, the WHO and UNICEF have called for schools around the globe to be made safer from the risk of COVID-19 transmission. Detailed guidance is needed on how this goal can be successfully implemented in a wide variety of educational settings in order to effectively mitigate impacts on the health of students, staff, their families, and society. This review provides a comprehensive synthesis of current scientific evidence and emerging standards in relation to the use of layered prevention strategies (involving masks, distancing, and ventilation), setting out the basis for their implementation in the school environment. In the presence of increasingly infectious SARS-Cov-2 variants, in-classroom teaching can only be safely maintained through a layered strategy combining multiple protective measures. The precise measures that are needed at any point in time depend upon a number of dynamic factors, including the specific threat-level posed by the circulating variant, the level of community infection, and the political acceptability of the resultant risk. By consistently implementing appropriate prophylaxis measures, evidence shows that the risk of infection from in-classroom teaching can be dramatically reduced. Current studies indicate that wearing high-quality masks and regular testing are amongst the most important measures in preventing infection transmission; whilst effective natural and mechanical ventilation systems have been shown to reduce infection risks in classrooms by over 80%.

[Ventilation concepts in schools for the prevention of transmission of highly infectious viruses (SARS-CoV-2) by aerosols in indoor air]. / Lüftungskonzepte in Schulen zur Prävention einer Übertragung hochinfektiöser Viren (SARS-CoV­2) über Aerosole in der Raumluft.

Exhaled aerosol particles play an important role in the transmission of SARS-CoV­2, particularly when many people gather indoors. This article summarises the knowledge on virus transmission in schools and practical measures to reduce aerosol-driven infections. A central preventive measure is to enhance room and building ventilation, i.e. the exchange of possibly contaminated indoor air with ambient air. Besides the concentrations of possibly infectious particles, ventilation reduces carbon dioxide concentrations, humidity and other chemical substances in indoor air as well. Irrespective of ventilation, face masks (surgical or FFP2) represent a vital part of hygiene measures. Fixed or mobile air purifiers can support these measures particularly when rooms providing only poor ventilation must be utilized. The article reflects the state of knowledge in October 2021 of the various techniques that have been shown as useful for the prevention of indirect infections. New variants of SARS-CoV­2, the progress of the vaccination campaign in children and adolescents, and the increase in general immunity might require a re-evaluation of the prevention strategies described. The COVID-19 pandemic has revealed common deficits in room and building ventilation, not least in schools. Apart from short-term measures for the prevention of airborne infectious diseases, a long-term strategy seems advisable to alleviate the deficits encountered in schools with respect to room and building ventilation. In view of a permanent improvement of indoor air and prevention against airborne infections the fitting of schools with fixed ventilation systems - preferably including heat and moisture recovery - appears to be a sustainable social investment.

Source apportionment of organic compounds in Berlin using positive matrix factorization - assessing the impact of biogenic aerosol and biomass burning on urban particulate matter.

Source apportionment of 13 organic compounds, elemental carbon and organic carbon of ambient PM(10) and PM(1) was performed with positive matrix factorization (PMF). Samples were collected at three sites characterized by different vegetation influences in Berlin, Germany in 2010. The aim was to determine organic, mainly biogenic sources and their impact on urban aerosol collected in a densely populated region. A 6-factor solution provided the best data fit for both PM-fractions, allowing the sources isoprene- and α-pinene-derived secondary organic aerosol (SOA), bio primary, primarily attributable to fungal spores, bio/urban primary including plant fragments in PM(10) and cooking and traffic emissions in PM(1), biomass burning and combustion fossil to be identified. With mean concentrations up to 2.6 µg Cm(-3), biomass burning dominated the organic fraction in cooler months. Concentrations for α-pinene-derived SOA exceeded isoprene-derived concentrations. Estimated secondary organic carbon contributions to total organic carbon (OC) were between 7% and 42% in PM(10) and between 11% and 60% in PM(1), which is slightly lower than observed for US- or Asian cities. Primary biogenic emissions reached up to 33% of OC in the PM(10)-fraction in the late summer and autumn months. Temperature-dependence was found for both SOA-factors, correlations with ozone and mix depth only for the α-pinene-derived SOA-factor. Latter indicated input of α-pinene from the borders, highlighting differences in the origin of the precursors of both factors. Most factors were regionally distributed. High regional distribution was found to be associated with stronger influence of ambient parameters and higher concentrations at the background station. A significant contribution of biogenic emissions and biomass burning to urban organic aerosol could be stated. This indicates a considerable impact on PM concentrations also in cities in a densely populated area, and should draw the attention concerning health aspects not only to cardio-vascular diseases but also to allergy issues.

NanoLINEN: nanotoxicology link between India and European Nations.

Nanotoxicology link between India and European Nations (NanoLINEN) is a consortium of 7 European laboratories and Indian Institute of Toxicology Research (CSIR Laboratory) from India to strengthen the research ties in the area of Nanomaterial Toxicology. The goal of this project is to develop robust risk assessment methodologies that will be useful for the community manufacturing and using nano-products.

Diisononyl 1,2-cyclohexanedicarboxylic acid (DINCH) and Di(2-ethylhexyl) terephthalate (DEHT) in indoor dust samples: concentration and analytical problems.

Possible human health effects of phthalate plasticizers have been intensely discussed during the last decade. Di(2-ethylhexyl) phthalate (DEHP), the phthalate acid ester with the largest production volume worldwide, has been substituted by new compounds like Diisononyl 1,2-cyclohexanedicarboxylic acid (DINCH) or Di(2-ethylhexyl) terephthalate (DEHT) in many applications. There are numerous reports about concentration levels of phthalates in indoor environments, but data on concentrations of these alternative plasticizers are not available yet. Also, the methods for the determination of phthalate substitutes are not yet established. This study presents the results achieved by quantification using different analytical methods. Data on the concentration of DEHT and DINCH in 953 dust samples from German households are presented. These samples were obtained in four different studies conducted from 1997 to 2009. Maximum concentrations of 110 mg DINCH/kg dust and 440 mg DEHT/kg dust were found. Especially the amount of DINCH has increased significantly after the market introduction of this plasticizer in 2002. Up to the beginning of 2006, DINCH was found in 44% of the dust samples. Dust samples collected in 2009 indicate an increased concentration for both softeners.

Genotoxicity biomonitoring in regions exposed to vehicle emissions using the comet assay and the micronucleus test in native rodent Ctenomys minutus.

Exposure to motor vehicle emissions represents an important concern for possible long-term health effects. The present report describes: 1) the application and verification of the alkaline comet assay in Ctenomys minutus to detect the possible genotoxicity of automobile emissions; 2) a comparison of the comet assay results with peripheral blood micronucleus (MN) assay results performed in the same animals; and 3) the identification of agents involved in the responses and in the seasonal variation of the effects. Ctenomys minutus (Octodontidae-Rodentia) were captured in two different fields from both sides of RS/030, a highway on the coastal plain of the Brazilian state of Rio Grande do Sul. Reference animals were obtained from a nearby field that was about 3 km distant from any road. By the end of this study, 123 rodents (73 females and 50 males) were live-trapped. Our results indicate that there was an increase in cells with DNA damage for C. minutus environmentally exposed to automobile emissions, as demonstrated by the alkaline comet assay, but there was no increase in micronucleated cells. The alkaline comet assay showed age and gender differences in the response. The comet assay results suggest that adult females are the principal population affected by air pollutants from vehicle emissions. Chemical data were also collected from areas exposed to automobile exhaust and these indicated that elevated levels of hydrocarbons, metals, and NO(2) were associated with the elevated levels of damaged cells observed in the wild rodent C. minutus. Our results agree with previous data on engine and fuel components, where weak increases in damage for native rodents exposed to emissions have been observed. Other larger, controlled studies are needed to better understand how the metabolism of C. minutus affects its response to emission exposure.