Assessment of SARS-CoV-2 airborne infection transmission risk in public buses.

Public transport environments are thought to play a key role in the spread of SARS-CoV-2 worldwide. Indeed, high crowding indexes (i.e. high numbers of people relative to the vehicle size), inadequate clean air supply, and frequent extended exposure durations make transport environments potential hotspots for transmission of respiratory infections. During the COVID-19 pandemic, generic mitigation measures (e.g. physical distancing) have been applied without also considering the airborne transmission route. This is due to the lack of quantified data about airborne contagion risk in transport environments. In this study, we apply a novel combination of close proximity and room-scale risk assessment approaches for people sharing public transport environments to predict their contagion risk due to SARS-CoV-2 respiratory infection. In particular, the individual infection risk of susceptible subjects and the transmissibility of SARS-CoV-2 (expressed through the reproduction number) are evaluated for two types of buses, differing in terms of exposure time and crowding index: urban and long-distance buses. Infection risk and reproduction number are calculated for different scenarios as a function of the ventilation rates (both measured and estimated according to standards), crowding indexes, and travel times. The results show that for urban buses, the close proximity contribution significantly affects the maximum occupancy to maintain a reproductive number of <1. In particular, full occupancy of the bus would be permitted only for an infected subject breathing, whereas for an infected subject speaking, masking would be required. For long-distance buses, full occupancy of the bus can be maintained only if specific mitigation solutions are simultaneously applied. For example, for an infected person speaking for 1 h, appropriate filtration of the recirculated air and simultaneous use of FFP2 masks would permit full occupancy of the bus for a period of almost 8 h. Otherwise, a high percentage of immunized persons (>80%) would be needed.

Close proximity risk assessment for SARS-CoV-2 infection.

Although the interpersonal distance represents an important parameter affecting the risk of infection due to respiratory viruses, the mechanism of exposure to exhaled droplets remains insufficiently characterized. In this study, an integrated risk assessment is presented for SARS-CoV-2 close proximity exposure between a speaking infectious subject and a susceptible subject. It is based on a three-dimensional transient numerical model for the description of exhaled droplet spread once emitted by a speaking person, coupled with a recently proposed SARS-CoV-2 emission approach. Particle image velocimetry measurements were conducted to validate the numerical model. The contribution of the large droplets to the risk is barely noticeable only for distances well below 0.6 m, whereas it drops to zero for greater distances where it depends only on airborne droplets. In particular, for short exposures (10 s) a minimum safety distance of 0.75 m should be maintained to lower the risk below 0.1%; for exposures of 1 and 15 min this distance increases to about 1.1 and 1.5 m, respectively. Based on the interpersonal distances across countries reported as a function of interacting individuals, cultural differences, and environmental and sociopsychological factors, the approach presented here revealed that, in addition to intimate and personal distances, particular attention must be paid to exposures longer than 1 min within social distances (of about 1 m).

A novel approach to evaluate the lung cancer risk of airborne particles emitted in a city.

Air quality still represents a main threat to human health in cities. Even in developed countries, decades of air pollution control not yet allowed to reduce pollutant concentrations in urban areas adequately. Indeed, high airborne particle concentrations are measured in several European cities; this is a main issue since particles represent a carrier for carcinogenic compounds. Numerous researches measuring the exposure to the different aerosol metrics in urban areas were recently performed, nonetheless, few data on the lung cancer risk in such environments are available. In the present paper a novel approach to evaluate the lung cancer risk related to the airborne particles emitted by the different sources located in a city is proposed and applied to a pilot case-study (i.e. an Italian city). In particular, an existing lung cancer risk model was modified and applied to assess the particle-related lung cancer "emitted" by the different sources of the city using pollutant emission factors provided by accredited emission inventory databases. Therefore, the average toxicity of the particles emitted by the city (i.e. lung cancer slope factor) and the lung cancer risk globally emitted by the city, expressed as new cases of lung cancer, were evaluated. The proposed emission inventory also allowed to identify and localize the main contributors to the overall risk emitted in a city. As an example, for the city under investigation, the research revealed that the main contributor, amongst the sources considered, is the vehicular traffic which is characterized by a lower mass fraction of carcinogenic compounds but a much higher sub-micron particle emission with respect to the other sources.

[Development of an integrated system of family medicine--pathologic anatomy service to start epidemiologic studies on tumors occurring in an area of southern Italy. First results]. / Costruzione di un sistema integrato medici di famiglia--servizi di anatomia patologica per l'avvio di studi epidemiologici sui tumori incidenti in un'area dell'Italia meridionale. Primi risultati.

In Italy there are eight tumor Population-Based Registries (PBRs) that publish incidence data, and only one of them (Ragusa) provides data for Southern Italy. Usually, PBRs are based on data collection from Pathologists and medical records. Our integrated system differentiates from traditional PBRs because the information comes from the General Practitioners (GPs) and is completed with the diagnosis provided by the Pathologists (Ps). During two years we have registered 1,057 new cancers on a middle period population of 212,644. GPs and Ps signed 395 and 879 incident cases, respectively. GPs alone provided 16.8%, Ps alone 62.6%, and either source 20.6% of total cases. After excluding non melanotic skin cancers and bladder carcinoma, the GPs-Ps integrated system counted 828 new cases in two years. These incidence data are the first in our region (Puglia). The 178 cases signed by GPs alone should have been lost if the informations of our PBR had been based only on local Ps' records. Moreover, 94 of GPs cases (11% of total cancers registered) were subjects who moved outside the area for diagnosis and treatment. Even if this article evaluates the effect of under-registration attributable to Ps or GPs, the cancer incidence data and the active involvement of GPs indicate that they could be usefully involved in the registration of cancer data.