Measurements from a network of air quality sensors gathered during a clinical study provide validation for the main part of the model. Overall, the model estimates staff exposure to airborne contamination from surgical smoke and biological material. To address the clinical implication over a long period of time, the systems approach is built upon previous work on multi-scale modeling of surgical flow in a large operating room suite and takes into account human behavior factors. Keywords: COVID; airborne virus; indoor air quality; multi-scale model; particle transport; surgical smoke; surgical suite.
To determine whether or not large macromolecules and viruses can diffuse through mucus, we observed the motion of proteins, microspheres, and viruses in fresh samples of human cervical mucus using fluorescent recovery after photobleaching and multiple image photography. Two capsid virus-like particles, human papilloma virus 55 nm, approximately 20, kDa and Norwalk virus 38 nm, approximately 10, kDa , as well as most of the globular proteins tested kDa diffused as rapidly in mucus as in saline.
Electron microscopy of cervical mucus confirmed that the mesh spacing between mucin fibers is large enough nm for small viruses to diffuse essentially unhindered through mucus. Ordinary Least Squares OLS method is applied for estimating the unknown parameters in linear regression models [1—3]. Table 1 shows that hinterland cities have a average higher level of infected individuals than coastal cities.
Table 2 shows that cities with low wind speed 7. Table 3 shows that cities in the central and southern part of Italy have a lower number of infected individuals than cities in North Italy. Descriptive statistics of Italian provincial capitals according to days exceeding the limits set for PM 10 or ozone.
These findings suggest that density of population per km 2 is important for transmission dynamics but other factors may support the acceleration of viral infectivity by COVID in association with higher probability of interpersonal contacts in cities having high population density.
Descriptive statistics of Italian provincial capitals according to density per km 2 2 categories. Descriptive statistics of Italian provincial capitals according to density per km 2 3 categories. The reduction of coefficients of correlation r between infected individuals and air pollution from 17th March to 7th April , and the increase of the association between infected people and density of people in cities over the same time period, controlling mutual variables, suggest that air pollution in cities seems to be a important factor in the initial phase of transmission dynamics of COVID i.
In the phase of the maturity of transmission dynamics 7th April , with lockdown that reduces air pollution, the mechanism of air pollution-to-human transmission of Coronavirus infection airborne viral infectivity reduces intensity, whereas coefficient of human-to-human transmission increases. These findings are confirmed with hierarchical regression that also reveals how air pollution in cities seems to be a driving factor of transmission dynamics in the initial phase of diffusion of COVID 17th March In the phase of the maturity of transmission dynamics of COVID 7th April , the determinant of air pollution is important to support the diffusion of viral infectivity of this airborne disease but it reduces the intensity, whereas the factor of human-to-human transmission increases, ceteris paribus Table This result reveals that transmission dynamics of COVID is due to human-to-human transmission but the factor of air pollution-to-human transmission of viral infectivity supports a substantial growth of spatial diffusion of vital infectivity.
Table 11 shows results of the transmission dynamics of COVID considering the interpersonal contacts, measured with density of population in cities understudy. In short, results suggest that density of population explains the number of infected individuals, increasing the probability of human-to-human transmission. In particular,. The statistical output of Table 11 is schematically summarized as follows:.
The policy implications here are clear: COVID has reduced transmission dynamics on population in the presence of lower level of air pollution and specific environments based on a higher wind speed e. Hence, the effect of accelerated transmission dynamics of COVID cannot be explained without accounting for the level of air pollution and other geo-environmental conditions of the cities, such as high wind speed and temperature. Note: This result reveals that transmission dynamics of COVID is due to two mechanisms given by: human-to-human transmission based on density of population and air pollution-to-human transmission airborne viral infectivity ; in particular, in polluting cities, the accelerated diffusion of viral infectivity is also due to mechanism of air pollution-to-human transmission that may have a stronger effect than human-to-human transmission!
A main question for supporting a strategy to prevent future epidemics similar to COVID is: What is the maximum number of days that cities can exceed the limits set for PM 10 or ozone per year, before that the combination between air pollution and meteorological conditions triggers a take-off of viral infectivity epidemic diffusion with damages for health of population, economy and society? The function based on Table 12 is:. Parametric estimates of the relationship of Infected individuals 7th April on days exceeding limits set for PM 10 or ozone regression analysis, quadratic model.
The minimization of this function is performed imposing first derivative y' equal to zero 0 :. Beyond this critical point, the analytical and geometrical output suggests that environmental inconsistencies, because of the combination between air pollution and meteorological conditions, trigger a take-off of viral infectivity epidemic diffusion with damages for health of population, economy and society. Estimated relationship of number of infected on days exceeding limits of PM 10 in Italian provincial capitals Quadratic model.
Finally, the reduction of unstandardized coefficient of regression in Table 13 , from 17th March to 7th April , suggests a deceleration of the diffusion of COVID over time and space.
The question is: how many days are necessary to stop the epidemic , ceteris paribus quarantine and lockdown? Coefficient of regression of the linear model per day based on Eq. Considering the results just mentioned, the fundamental questions are:. Why did this Coronavirus infection spread so rapidly in Italy and other countries?
How is the link between geographical and environmental factors and accelerated diffusion of COVID in specific regions? Studies show that the diffusion of viral infectivity depends on the interplay between host factors and environment Neu and Mainou, ; Morawska and Cao, In this context, it is critical to explain how air quality can affect viral dissemination at national and global level Das and Horton, Many ecological studies have examined the association between the incidence of invasive pneumococcal disease, respiratory virus circulation and various climatic factors McCullers, ; Jansen et al.
These studies show that in temperate climates, the epidemiology of invasive pneumococcal disease has a peak of incidence in winter months Dowell et al. Brunekreef and Holgate, a , Brunekreef and Holgate, b argue that, in addition to climate factors, the health effects of air pollution have been subject to intense investigations in recent years.
Air pollution is ubiquitous in manifold urban areas of developed and developing nations. Air pollution has gaseous components and particulate matter PM. The former includes ozone O 3 , volatile organic compounds VOCs , carbon monoxide CO and nitrogen oxides NO x that generate inflammatory stimuli on the respiratory tract of individuals Glencross et al.
PM has a complex composition that includes metals, elemental carbon and organic carbon both in hydrocarbons and peptides , sulphates and nitrates, etc.
Ghio et al. Advanced countries, such as in Europe, have more and more smog because of an unexpected temperature inversion, which traps polluting emissions from the city near ground-level mainly in winter season. The ambient pollution mixes with moisture in the air to form a thick fog that affects the health of people in the city Wang et al. The exposure to pollutants, such as airborne particulate matter and ozone, generates respiratory and cardiovascular diseases with increases in mortality and hospital admissions cf.
Wei et al. Zhang et al. As bacteria size typically ranges from 0. Moreover, because of regional bio aerosol transportation, harmful microbial components and bacterial aerosols have dangerous implications on human health and also plantation cf. Harmful bio aerosol components including pathogens, antibiotic-resistant bacteria and endotoxins can cause severe respiratory and cardiovascular diseases in society Charmi et al. In fact, the concentration of microbes, pathogens and toxic components significantly increases during polluted days, compared to no polluted days Liu et al.
In addition, airborne bacterial community structure changes with pollutant concentration, which may be related to bacterial sources and multiplication in the air T. Studies also indicate that microbial community composition and bioactivity are significantly affected by particle concentration Liu et al. To put it differently, the atmospheric particulate matter harbors more microbes during polluted days than sunny or clean days Wei et al.
In fact, viable bio aerosol particles and high microbial concentration in particulate matter play their non-negligible role during air pollution and transmission dynamics of viral infectivity T. For instance, studies on airborne bacteria in PM 2. Xie et al. Liu et al. Sun et al. In general, bio aerosol concentrations are influenced by complex factors, such as emission sources, terrain, meteorological conditions and other climate factors Zhai et al.
Results suggest that from clean days to high polluted days, bacterial community structure is influenced by bacterial adaptation to pollutants, chemical composition of pollutants and meteorological conditions cf. Moreover, certain bacteria from Proteobacteria and Deinococcus-Thermus have high tolerance towards environmental stresses and can adapt to extreme environments.
As a matter of fact, bacilli can survive to harsh environments by forming spores. Moreover, certain bacteria with protective mechanisms can survive in highly polluted environments, while other bacteria cannot withstand such extreme conditions. In particular, bacteria survive in the atmosphere adapting to ultraviolet exposure, reduced nutrient availability, desiccation, extreme temperatures and other factors. In short, in the presence of accumulated airborne pollutants, more microorganisms might be attached to particulate matter.
Thus, in heavy or severe air pollution, highly toxic pollutants in PM 2. Numerous studies also indicate that the combination between meteorological conditions and air pollution creates an appropriate environment for microbial community structure and abundance, and diffusion of viral infectivity cf.
Zhong et al. In general, bacterial communities during aerosol pollution are influenced by bacterial adaptive mechanisms, particle composition, and meteorological conditions. The particles could also act as carriers, which have complex adsorption and toxicity effects on bacteria Wei et al. Certain particle components are also available as nutrition for bacteria and the toxic effect dominates in heavy pollution. The bacterial adaptability towards airborne pollutants can cause bacterial survival or death for different species.
Groulx et al. Hence, microorganisms may be influenced by interactions with ambient particles leading to the inhibition or enhancement of viability e.
Moreover, Groulx et al. Preliminary evidence suggests that the interactions between airborne viruses and airborne fine particulate matter influence viral stability and infectivity …..
The development of a platform to study interactions between artificial bio aerosols and concentrated ambient particles provides an opportunity to investigate the direction, magnitude and mechanistic basis of these effects, and to study their health implications.
Thus, the variation in bacterial community structure is related to different pollution intensities. In heavy or severe pollution, bacteria that are adaptable to harsh environments, increase. In moderate pollution, PM 2. Therefore, effective measures should control health risks caused by bio aerosols during air pollution, especially for immunocompromised, such as elderly and other fragile individuals. Papi et al. Ko et al.
De Serres et al. Moreover, the study by Wei et al. This study supports our results that coastal cities in Italy have a lower air pollution and the diffusion of viral infectivity by COVID is lower than hinterland cities having a high level of air pollution cf. Other studies have reported associations between air pollution and reduced lung function, increased hospital admissions, increased respiratory symptoms and high asthma medication use Simoni et al.
In this context, the interaction between climate factors, air pollution and increased morbidity and mortality of people and children from respiratory diseases is a main health issue in society Darrow et al. Asthma is a disease associated with exposure to traffic-related air pollution and tobacco smoking Liao et al. Many studies show that exposure to traffic-related outdoor air pollutants e. Especially, high levels of PM 10 increases cough, lower respiratory disorders and lower peak expiratory flow Ward and Ayres, ; Nel, Weinmayr et al.
Furthermore, asthma symptoms are exacerbated by air pollutants, such as diesel exhaust, PM 10 , NO 2 , SO 2 , O 3 and respiratory virus, such as adenovirus, influenza, parainfluenza and respiratory syncytial virus Jaspers et al. The study by Liao et al. Some studies focus on the effect of meteorology and air pollution on acute viral respiratory infections and viral bronchiolitis a disease linked to seasonal changes in respiratory viruses in the first years of life Nenna et al.
Carugno et al. Results suggest that seasonal weather conditions and concentration of air pollutants seem to influence RSV-related bronchiolitis epidemics in Italian urban areas.
In fact, airborne particulate matter may influence the children's immune system and foster the spread of RSV infection. This study also shows a correlation between short- and medium-term PM 10 exposures and increased risk of hospitalization because of RSV bronchiolitis among infants. In short, manifold environmental factors- such as air pollution levels, circulation of respiratory viruses and colder temperatures -induce longer periods of time spent indoors with higher opportunities for diffusion of infections between people.
Studies also show that air pollution is higher during winter months and it has been associated with increased hospitalizations for respiratory diseases and other disorders Ko et al. Moreover, oscillations in temperature and humidity may lead to changes in the respiratory epithelium, which increase susceptibility to infections Deal et al.
Murdoch and Jennings correlate the incidence rate of invasive pneumococcal disease IPD with fluctuations in respiratory virus activity and environmental factors in New Zealand, showing how incidence rates of IPD are associated with the increased activity of some respiratory viruses and air pollution.
Another side effect of air pollution exposure is the high incidence of mumps. In fact, Hao et al. Instead, Yang et al. Moreover, the effect of air pollution in the cold season is higher than in the warm season. Shepherd and Mullins analyze the relationship between arthritis diagnosis in those over 50 and exposure to extreme air pollution in utero or infancy. In particular, this study links early-life air pollution exposure to later-life arthritis diagnoses, and suggests a particularly strong link for Rheumatoid arthritis.
Overall, then, these studies suggest complex relationships between people, meteorological conditions, air pollution and viral infectivity over time and space. The composition of ambient particulate matter PM varies both geographically and seasonally because of the mix of sources at any location across time and space. A vast literature shows short-term effects of air pollution on health, but air pollution affects morbidity also in the long run Brunekreef and Holgate, a , Brunekreef and Holgate, b.
The damages of air pollution on health can be explained as follows. Air pollutants exert toxic effects on respiratory and cardiovascular systems of people; in addition, ozone, oxides of nitrogen, and suspended particulates are potent oxidants, either through direct effects on lipids and proteins or indirectly through the activation intracellular oxidant pathways Rahman and MacNee, Studies of animal and human in-vitro and in-vivo exposure have demonstrated the powerful oxidant capacity of inhaled ozone with activation of stress signaling pathways in epithelial cells Bayram et al.
Lewtas shows that exposures to combustion emissions and ambient fine particulate air pollution are associated with genetic damages. Long-term epidemiologic studies report an increased risk of all causes of mortality, cardiopulmonary mortality, and lung cancer mortality associated with higher exposures to air pollution cf.
An increasing number of studies- investigating cardiopulmonary and cardiovascular disorders -shows potential causative agents from air pollution combustion sources. About the respiratory activity, the adult lung inhales approximately 10—11, L of air per day, positioning the respiratory epithelium for exposure to high volumes of pathogenic and environmental insults.
In fact, respiratory mucosa is adapted to facilitate gaseous exchange and respond to environmental insults efficiently, with minimal damage to host tissue. The respiratory mucosa consists of respiratory tract lining fluids; bronchial and alveolar epithelial cells; tissue resident immune cells, such as alveolar macrophages, dendritic cells, innate lymphoid cells and granulocytes; as well as adaptive memory T and B lymphocytes. In health, the immune system responds effectively to infections and neoplastic cells with a response tailored to the insult, but immune system must not respond harmfully to the healthy body and benign environmental influences.
A well-functioning immune system is vital for a healthy body. Inadequate and excessive immune responses generate manifold pathologies, such as serious infections, metastatic malignancies and auto-immune conditions Glencross et al. In particular, immune system consists of multiple types of immune cells that act together to generate or fail to generate immune responses.
In this context, the relationships between ambient pollutants and immune system is vital to explain how air pollution causes diseases and respiratory disorders in the presence of Coronavirus infection. Glencross et al. In general, air pollutants stimulate pro-inflammatory immune responses across multiple classes of immune cells. In particular, the association between high ambient pollution and exacerbations of asthma and chronic obstructive pulmonary disease COPD is consistent with immunological mechanisms.
Studies confirm associations between elevated ambient particulate matter and worsening of lung function in patients with COPD Bloemsma et al. In short, associations between ambient pollution and airways exacerbations are stronger than associations with development of chronic airways diseases. In addition, studies suggest an action of air pollution to augment Th2 immune responses and perturb antimicrobial immune responses.
This mechanism also explains the association between high air pollution and increased exacerbations of asthma — a disease characterized by an underlying Th2 immuno-pathology in the airways with severe viral-induced exacerbations. As inhaled air pollution deposits primarily on respiratory mucosa, potential strategies to reduce such effects may be based on vitamin D supplementation.
Studies show that plasma levels of vitamin D, activated by ultraviolet B, are significantly higher in summer and fall than winter and spring season, in a latitude-dependent manner Barger-Lux and Heaney, Since the temperature and hour of sun depend on latitude, Oh et al.
For instance, breast cancer incidence correlates inversely with the levels of serum vitamin D and ultraviolet B exposure, which have the highest intensity in summer season. The relationships between adequate supply of vitamin D and low cancer risk are relevant to breast cancer, colon, prostate, endometrial, ovarian, and also lung cancer Zhou et al.
In the context of this study, and considering the negative effects of air pollution on human health and transmission dynamics of Coronavirus infection, summer season may have twofold effects to reduce diffusion of COVID At the end of , medical professionals in Wuhan China were treating cases of pneumonia and respiratory disorders that had an unknown source Li et al.
By January 23, , Chinese authorities had shut down transportation going into and out of Wuhan, as well as local businesses, in order to reduce the spread of the Severe Acute Respiratory Syndrome Coronavirus 2 Centers for Disease Control and Prevention, ; Public Health England, ; Manuell and Cukor, It is the beginning of several quarantines set up in China and other countries around the world to cope with transmission dynamics of COVID Quarantine is the separation and restriction of movement of people who have potentially been exposed to a contagious disease to ascertain if they become unwell, in order to reduce the risk of them infecting others Brooks et al.
In short, quarantine can generate a strong reduction of the transmission of viral infectivity. In fact, Italy was not able to prevent the diffusion of of Coronavirus infection and has applied quarantine as a recovery strategy to lessen the health and socioeconomic damages caused by this pandemic. In addition, Italy applied non-pharmaceutical interventions based on physical distancing, school and store closures, workplace distancing, to avoid crowded places, similarly to measures applied to COVID outbreak in Wuhan cf.
The benefits to support these measures until May are aimed at delaying and reducing the height of epidemic peak, affording health-care systems more time to expand and respond to this emergency and, as a result reducing the final impact of COVID epidemic in society.
In general, non-pharmaceutical interventions are important factors to reduce the epidemic peak and the acute pressure on the health-care system Prem et al.
However, Brooks et al. Stressors included longer quarantine duration, infection fears, frustration, boredom, inadequate supplies, inadequate information, financial loss, and stigma. Some researchers have suggested long-lasting effects. In situations where quarantine is deemed necessary, officials should quarantine individuals for no longer than required, provide clear rationale for quarantine and information about protocols, and ensure sufficient supplies are provided.
This strategy, of course, does not prevent future epidemics similar to the COVID and it does not protect regions from future Coronavirus disease threats on population. Nations have to apply proactive strategies that anticipate these potential problems and prevent them, for reducing the health and economic impact of future epidemics in society.
Daszak et al. In addition, the application of best practices of high surveillance and proper biosafety procedures in public and private institutes of virology that study viruses and new viruses to avoid that may be accidentally spread in surrounding environments with damages for population, vegetation and overall economy of nations.
In this context, international collaboration among scientists is basic to address these risks and support decisions of policymakers to prevent future pandemic that creates huge socioeconomic issues worldwide cf. New technology, for years to come, can cope with consequential epidemic outbreaks, also redefining the way governments interact with their citizens, such as the expanded use of surveillance tools, defending against cyberattacks and misinformation campaigns, etc.
This study here shows that accelerated diffusion of COVID is also likely associated with high air pollution and specific meteorological conditions low wind speed, etc. North Italy is one of the European regions with the highest motorization rate and polluting industrialization cf.
In , the daily limits for PM 10 or ozone were exceeded in 55 provincial capitals i. In 24 of the 55 Italian province capitals, the limit was exceeded for both parameters, with negative effects on population and subsequent health problems in the short and long run. In fact, Italian cities having a very high number of polluted days are mainly in North Italy: e.
These provincial capitals of the River Po area in Italy have exceeded in at least one of the two limits just mentioned. The first city not located in the Po Valley is Frosinone Lazio region in the central part of Italy with days of exceedance 83 days for the PM 10 and 33 days for the ozone , followed by Avellino, a city close to Naples in South Italy with total 89 days: 46 days for PM 10 and 43 days for ozone and Terni with 86 days respectively 49 and 37 days for the two pollutants.
Many cities in Italy are affected by air pollution and smog because of traffic, domestic heating, industries and agricultural practices and private cars that continue to be by far the most used means of transportation more than 39 million cars in A major source of emissions of nitrogen oxides into the atmosphere is the combustion of fossil fuels from stationary sources heating, power generation, etc.
Although local lockdown on February 25, , the Regional Agency for Environmental Protection showed concentrations of PM 10 beyond the limits in almost all of Lombardy region. The day after, February 26, , the high intensity of wind speed swept the entire Po Valley, bringing to Lombardy region a substantial reduction in the average daily concentrations of PM 10 i.
These observations associated with statistical analyses here suggest that high concentration of nitrogen dioxide of particulate air pollutants emitted by motor vehicles, power plants, and industrial facilities in North Italy seems to be a platform to support the diffusion of viral infectivity cf. As a matter of fact, transmission dynamics of COVID has found in air pollution and meteorological conditions of North Italy an appropriate environment and population for an accelerated diffusion that is generating more than 26, deaths and a huge number of hospitalizations in a short period of time February—March—April The maps in Fig.
The reduction in NO 2 pollution is apparent in all North Italy.
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