Experimental and in silico evaluations of the possible molecular interaction between airborne particulate matter and SARS-CoV-2.

During the early stage of the COVID-19 pandemic (winter 2020), the northern part of Italy has been significantly affected by viral infection compared to the rest of the country leading the scientific community to hypothesize that airborne particulate matter (PM) could act as a carrier for the SARS-CoV-2. To address this controversial issue, we first verified and demonstrated the presence of SARS-CoV-2 RNA genome on PM2.5 samples, collected in the city of Bologna (Northern Italy) in winter 2021. Then, we employed classical molecular dynamics (MD) simulations to investigate the possible recognition mechanism(s) between a newly modelled PM2.5 fragment and the SARS-CoV-2 Spike protein. The potential molecular interaction highlighted by MD simulations suggests that the glycans covering the upper Spike protein regions would mediate the direct contact with the PM2.5 carbon core surface, while a cloud of organic and inorganic PM2.5 components surround the glycoprotein with a network of non-bonded interactions resulting in up to 4769 total contacts. Moreover, a binding free energy of -207.2 ± 3.9 kcal/mol was calculated for the PM-Spike interface through the MM/GBSA method, and structural analyses also suggested that PM attachment does not alter the protein conformational dynamics. Although the association between the PM and SARS-CoV-2 appears plausible, this simulation does not assess whether these established interactions are sufficiently stable to carry the virus in the atmosphere, or whether the virion retains its infectiousness after the transport. While these key aspects should be verified by further experimental analyses, for the first time, this pioneering study gains insights into the molecular interactions between PM and SARS-CoV-2 Spike protein and will support further research aiming at clarifying the possible relationship between PM abundance and the airborne diffusion of viruses.

Lessons learnt for air pollution mitigation policies from the COVID-19 pandemic: The Italian perspective.

Policies to improve air quality need to be based on effective plans for reducing anthropogenic emissions. In 2020, the outbreak of COVID-19 pandemic resulted in significant reductions of anthropogenic pollutant emissions, offering an unexpected opportunity to observe their consequences on ambient concentrations. Taking the national lockdown occurred in Italy between March and May 2020 as a case study, this work tries to infer if and what lessons may be learnt concerning the impact of emission reduction policies on air quality. Variations of NO2, O3, PM10 and PM2.5 concentrations were calculated from numerical model simulations obtained with business as usual and lockdown specific emissions. Both simulations were performed at national level with a horizontal resolution of 4 km, and at local level on the capital city Rome at 1 km resolution. Simulated concentrations showed a good agreement with in-situ observations, confirming the modelling systems capability to reproduce the effects of emission reductions on ambient concentration variations, which differ according to the individual air pollutant. We found a general reduction of pollutant concentrations except for ozone, that experienced an increase in Rome and in the other urban areas, and a decrease elsewhere. The obtained results suggest that acting on precursor emissions, even with sharp reductions like those experienced during the lockdown, may lead to significant, albeit complex, reduction patterns for secondary pollutant concentrations. Therefore, to be more effective, reduction measures should be carefully selected, involving more sectors than those related to mobility, such as residential and agriculture, and integrated on different scales.

Emission Factors of CO2 and Airborne Pollutants and Toxicological Potency of Biofuels for Airplane Transport: A Preliminary Assessment.

Aviation is one of the sectors affecting climate change, and concerns have been raised over the increase in the number of flights all over the world. To reduce the climate impact, efforts have been dedicated to introducing biofuel blends as alternatives to fossil fuels. Here, we report environmentally relevant data on the emission factors of biofuel/fossil fuel blends (from 13 to 17% v/v). Moreover, in vitro direct exposure of human bronchial epithelial cells to the emissions was studied to determine their potential intrinsic hazard and to outline relevant lung doses. The results show that the tested biofuel blends do not reduce the emissions of particles and other chemical species compared to the fossil fuel. The blends do reduce the elemental carbon (less than 40%) and total volatile organic compounds (less than 30%) compared to fossil fuel emissions. The toxicological outcomes show an increase in oxidative cellular response after only 40 min of exposure, with biofuels causing a lower response compared to fossil fuels, and lung-deposited doses show differences among the fuels tested. The data reported provide evidence of the possibility to reduce the climate impact of the aviation sector and contribute to the risk assessment of biofuels for aviation.

Size resolved aerosol respiratory doses in a Mediterranean urban area: From PM10 to ultrafine particles.

In the framework of the 2017 "carbonaceous aerosol in Rome and Environs" (CARE) experiment, particle number size distributions have been continuously measured on February 2017 in downtown Rome. These data have been used to estimate, through MPPD model, size and time resolved particle mass, surface area and number doses deposited into the respiratory system. Dosimetry estimates are presented for PM10, PM2.5, PM1 and Ultrafine Particles (UFPs), in relation to the aerosol sources peculiar to the Mediterranean basin and to the atmospheric conditions. Particular emphasis is focused on UFPs and their fraction deposited on the olfactory bulb, in view of their possible translocation to the brain. The site of PM10 deposition within the respiratory system considerably changes, depending on the aerosol sources and then on its different size distributions. On making associations between health endpoints and aerosol mass concentrations, the relevant coarse and fine fractions would be more properly adopted, because they have different sources, different capability of penetrating deep into the respiratory system and different toxicological implications. The separation between them should be set at 1 µm, rather than at 2.5 µm, because the fine fraction is considerably less affected by the contribution of the natural sources. Mass dose is a suitable metric to describe coarse aerosol events but gives a poor representation of combustion aerosol. This fraction of particles, made of UFPs and of accumulation mode particles (mainly with size below 0.2 µm), is of high health relevance. It elicited the highest oxidative activity in the CARE experiment and is properly described by the particle surface area and by the number metrics. Such metrics are even more relevant for the UFP doses deposited on the olfactory bulb, in consideration of the role recognized to oxidative stress in the progression of neurodegenerative diseases. Such metrics would be more appropriate, rather than PMx mass concentrations, to correlate neurodegenerative pathologies with aerosol pollution.

Is it the time to study air pollution effects under environmental conditions? A case study to support the shift of in vitro toxicology from the bench to the field.

Air pollution and particulate matter are recognised cause of increased disease incidence in exposed population. The toxicological processes underlying air pollution associated effects have been investigated by in vivo and/or in vitro experimentation. The latter is usually performed by exposing cells cultured under submerged condition to particulate matter concentration quite far from environmental exposure expected in humans. Here we report for the first time the feasibility of a direct exposure of air liquid interface cultured cells to environmental concentration of particulate matter. Inflammatory proteins release was analysed in cell medium while differential expression of selected genes was analysed in cells. Significant association of anti-oxidant genes was observed with secondary and aged aerosol, while cytochrome activation with primary and PAHs enriched ultrafine particles. The results obtained clearly show the opportunity to move from the lab bench to the field for properly understanding the toxicological effects also of ultrafine particles on selected in vitro models.

[Environmental indicators in ten Italian cities (2001-2005): the air quality data for epidemiological surveillance]. / Indicatori ambientali in dieci città italiane (2001-2005): i dati di qualità dell'aria per la sorveglianza epidemiologica.

OBJECTIVE: to produce environmental indicators suitable for an epidemiological surveillance in 10 Italian cities part of the EpiAir Project (2001-2005). METHODS: the environmental parameters that correlate to relevant health effects are the particles with diameters less than or equal to 10 micrometers (PM10), the nitrogen dioxide (NO2) and the ozone (O3). The necessary meteorological data are: temperature, relative humidity, barometric pressure and apparent temperature.We have identified some criteria to select monitoring stations and have taken standard methods of calculation to produce environmental indicators starting from the daily data available after closely evaluating the completeness of the existing data. Furthermore, we have checked the homogeneity of the selected data to ensure that it represents the population's exposure. RESULTS: close examination of descriptive statistics shows a critical situation of the considered pollutants. The analysis of the yearly state underlines for PM10 values higher than 40 microg/m3 in the area of Mestre-Venice and in Milan, Turin, Bologna e Taranto. For NO2, values are consistently above 40 microg/m3 in Milan, Turin, Bologna, Florence, Rome and Palermo. For ozone, the concentrations were stable, with the exception of Summer 2003 when we recorded, on average, an increase of 13% compared to the mean value estimated for the ten cities during the study period, especially in Mestre-Venice, Turin and Palermo. CONCLUSIONS: it is important to ensure the consistency of the methods and instruments in environmental monitoring. To evaluate health effects and perform interventions over the longterm, it is therefore fundamental that the data be homogenous, especially during the periodic reorganizations and rationalizations of air quality management. It is also necessary to include daily meteorological data that influence pollutant dispersion and population health status.

[MINNI, the national integrated modelling system for assessing the impacts of atmospheric pollution and the effectiveness of the emissions abatement strategies]. / Il sistema MINNI, modello integrato nazionale per la valutazione degli effetti dell'inquinamento atmosferico e dell'efficacia delle politiche di riduzione delle emissioni di inquinanti atmosferici.

Selecting the best emissions abatement strategy is very difficult due to the complexity of the processes that determine the impact of atmospheric pollutants and to the connection with climate change issues. Atmospheric pollution models can provide policy makers with a tool for assessing the effectiveness of abatement measures and their associated costs. The MINNI integrated model has been developed to link policy and atmospheric science and to assess the costs of the measures. The results have been carefully verified in order to identify uncertainties and the models are continuously updated to represent the state of the art in atmospheric science. The fine spatial and temporal resolution of the simulations provide a strong basis for assessing impacts on environment and health.