Comparing aerosol concentrations and particle size distributions generated by singing, speaking and breathing

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has resulted in an unprecedented shutdown in social and economic activity, with the cultural sector particularly severely affected. Restrictions on musical performances have arisen from a perception that there is a significantly higher risk of aerosol production from singing than speaking, based upon high-profile examples of clusters of COVID-19 following choral rehearsals. However, comparing aerosol generation from different types of vocalization, including singing, across a range of volumes is a rapidly evolving area of research. Here, we measured aerosols from singing, speaking and breathing from a large cohort of 25 professional singers in a range of musical genres in a zero-background environment, allowing unequivocal attribution of aerosol production to specific vocalizations. We do not assess the relative volumes at which people speak and sing. However, both showed steep increases in mass concentration with increase in loudness (spanning a factor of 20–30 across the dynamic range measured, p < 0.001). At the quietest volume (50 to 60 dBA), neither singing (p = 0.19) nor speaking (p = 0.20) were significantly different to breathing. At the loudest volume (90 to 100 dBA), a statistically significant difference (p < 0.001) was observed between singing and speaking, but with singing only generating a factor of between 1.5 and 3.4 more aerosol mass. Guidelines for musical performances should be based on the loudness and duration of the vocalization, the number of participants and the environment in which the activity occurs, rather than the type of vocalization. Mitigations such as the use of amplification and increased attention to ventilation should be employed where practicable

Biogeographical patterns in the British and Irish flora

The hectad (10 × 10 km square) distributions of the 1405 native British and Irish vascular plants were classified by the SPHERIKM cluster analysis program into 20 clusters, each of which is characterised by the key species used to initiate the cluster. The clusters reflect the influence of climate, altitude, geology and habitat on distribution patterns at this scale. Clusters with restricted distributions have high concentrations of threatened species, particularly the Medicago sativa cluster, centred on Breckland (55% of the species are threatened in Britain, although only 29% are regarded as priorities for conservation), and the Carex atrata cluster of montane species (45% threatened, and 49% conservation priority species). Some clusters are composed predominantly of species with similar European distributions whereas others are much more phytogeographically heterogeneous. A comparison with a similar analysis of the distribution of British and Irish mosses and liverworts reveals many similarities, especially between the vascular plants and the mosses, although there are many more common vascular plants than bryophytes and many more coastal species

Modeling Species Distributions from Heterogeneous Data for the Biogeographic Regionalization of the European Bryophyte Flora

The definition of biogeographic regions provides a fundamental framework for a range of basic and applied questions in biogeography, evolutionary biology, systematics and conservation. Previous research suggested that environmental forcing results in highly congruent regionalization patterns across taxa, but that the size and number of regions depends on the dispersal ability of the taxa considered. We produced a biogeographic regionalization of European bryophytes and hypothesized that (1) regions defined for bryophytes would differ from those defined for other taxa due to the highly specific eco-physiology of the group and (2) their high dispersal ability would result in the resolution of few, large regions. Species distributions were recorded using 10,000 km2 MGRS pixels. Because of the lack of data across large portions of the area, species distribution models employing macroclimatic variables as predictors were used to determine the potential composition of empty pixels. K-means clustering analyses of the pixels based on their potential species composition were employed to define biogeographic regions. The optimal number of regions was determined by v-fold cross-validation and Moran's I statistic. The spatial congruence of the regions identified from their potential bryophyte assemblages with large-scale vegetation patterns is at odds with our primary hypothesis. This reinforces the notion that post-glacial migration patterns might have been much more similar in bryophytes and vascular plants than previously thought. The substantially lower optimal number of clusters and the absence of nested patterns within the main biogeographic regions, as compared to identical analyses in vascular plants, support our second hypothesis. The modelling approach implemented here is, however, based on many assumptions that are discussed but can only be tested when additional data on species distributions become available, highlighting the substantial importance of developing integrated mapping projects for all taxa in key biogeographically areas of Europe, and the Mediterranean peninsulas in particular. © 2013 Mateo et al