The global pandemic of COVID-19 has been associated with infections and deaths among health-care workers. This Viewpoint of infectious aerosols is intended to inform appropriate infection control measures to protect health-care workers. Studies of cough aerosols and of exhaled breath from patients with various respiratory infections have shown striking similarities in aerosol size distributions, with a predominance of pathogens in small particles (

Knowing the facts about airborne particulates can make you more effective in managing the hazards they present.

The US Centers for Disease Control and Prevention updated guidance on its website to say coronavirus can commonly spread "through respiratory droplets or small particles, such as those in aerosols," which are produced even when a person breathes.

Is the transmission of novel coronavirus disease (COVID-19) weather dependent?. Journal of the Air & Waste Management Association. Accepted .

Introduction This chapter focuses on the acute effects on the lung after exposure to toxic substances. As used in this chapter, acute indicates short-term exposures (minutes to hours), with the ini…

"Dust is by far the most frequent source of environment-based bacteria and fungi along with the allergens and toxins associated with them. Such dust settled on carpets and upholstery may become resuspended" "Biofilms formed in car heaters/air conditioners [11, 12] as well as those in windshield washer reservoirs [13] and other areas of the car may release microbes such as legionellae and possibly environmental or nontuberculous mycobacteria (NTM) as well as airborne opportunistic pathogens. Such pathogens may also come from road dust and water in road puddles [14]." "Risk of influenza spread ranged from 59% to 99.9% for a 90 min trip when air was recirculated." "Potential health benefits of car deodorizers would be greater if they could additionally reduce the levels of airborne allergens, harmful chemicals, and particulates including PM2.5

***"PM is small enough to suspend in the air for long periods of time, which may provide “condensation nuclei” to which virus droplets attach [45]. Many studies have also reported that PM induces both airway epithelial damage and barrier dysfunction, which could result in a temporary immunosuppressive pulmonary microenvironment " "PM2.5 had almost no effect on influenza incidence at the non-flu season" "when PM2.5 was beyond 70 μg/m3, the effect of PM2.5 had an increasing gradient as PM2.5 increased. Such pattern was clearly more substantial in the middle aged groups and tended to be most pronounced for age group 25–59" "virulence of influenza is expected to be stronger near zero than at subfreezing temperatures and a decrease in temperature makes airways more susceptible to the onset of respiratory infections"

{Normal time periods of viability} "This project investigates survival of airborne influenza virus of different sub-types at common room conditions where risk of disease due to microbial transmission could be particularly high, especially at poorly ventilated environments, where viral concentration in the air reaches significant magnitudes. The results obtained for H1N1 and H5N1 strains show close trend with regards to inactivation in the ambient air; rapid inactivation of approximately 60% of microorganisms over the first 30 min with following inactivation at much slower rate over the remaining 60 min of experiment. A different picture was observed for the H3N2 strain, which demonstrated much higher robustness compared to other subtypes; even after 90 min, around 50% of viral particles were still alive."

Influenza A viruses are believed to spread between humans through contact, large respiratory droplets and small particle droplet nuclei (aerosols), but the relative importance of each of these modes of transmission is unclear. Volunteer studies suggest ...

Includes analyses of effects of humidity on transmission

We analyze the possibility of aerosol transmission of the novel coronavirus. Relevant strategies for preventing novel coronavirus pneumonia are established for the medical personnel and general public during their work or daily life. Chinese Journal of Ophthalmology.

At least indoors, where desiccation is the predominant stress, the general reversibility of membrane-phase changes by vapour-phase rehydration when coupled with efficacious microbial enzymatic repair mechanisms under genetic control, virtually ensures the spread of disease by the aerobiological pathway.

In epidemiological studies where the relationship between moisture in the indoor climate, respiratory symptoms and exposure to allergens is investigated it will be necessary to analyze the role of respiratory viruses in relation to respiratory symptoms. Today, the necessary techniques to address the …

The vast majority of studies reviewed here concern hospital and other health facilities where viruses are a well-known cause of occupational and nosocomial infec-tions. Studies on other indoor environments, on the other hand, including homes, non-industrial workplaces and public buildings, are scarce. The lack of regulations, threshold values and standardized detection meth-ods for viruses in indoor environments, make both research and interpretation of results difficult in this field, hampering infection control efforts. Further research will be needed to achieve a better understanding of virus survival in aerosols and on surfaces, and to elucidate the relationship between viruses and indoor environmental characteristics.

HCPs within 1.829 m of patients with influenza could be exposed to infectious doses of influenza virus, primarily in small-particle aerosols. This finding questions the current paradigm of localized droplet transmission during non-aerosol-generating procedures.

The update officially acknowledges growing evidence that under certain conditions, people farther than six feet apart can become infected by tiny droplets and particles that float in the air for minutes and hours, and that they play a role in the pandemic.

There is overwhelming evidence that inhalation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents a major transmission route for coronavirus disease 2019 (COVID-19). There is an urgent need to harmonize discussions about modes of virus transmission across disciplines to ensure the most effective control strategies and provide clear and consistent guidance to the public. To do so, we must clarify the terminology to distinguish between aerosols and droplets using a size threshold of 100 μm, not the historical 5 μm ([ 1 ][1]). This size more effectively separates their ...

Most spread the virus to only a few people — or none at all. But a small percentage transmit it with alarming efficiency, studies show.

CDC provides credible COVID-19 health information to the U.S.

Many of the sharpest increases per capita over the past week came in states like Wisconsin, Utah, Iowa and the Dakotas.

"People infected with SARS-CoV-2 exhaled 1,000–100,000 copies per minute of viral RNA, a marker of the pathogen’s presence. Because the volunteers simply breathed out, the viral RNA was probably carried in aerosols." "When researchers created aerosols of the new coronavirus, the aerosols remained infectious for at least 16 hours, and had greater infectivity than did those of the coronaviruses SARS-CoV and MERS-CoV." "No amount of ventilation could have reduced the risk to an acceptable level for the two-and-a-half-hour rehearsal, she says." "SARS-CoV-2 in mock saliva aerosols lost 90% of its viability in 6 minutes of exposure to summer sunlight, compared with 125 minutes in darkness."

Patients with respiratory manifestations of COVID-19 produce aerosols in the absence of aerosol-generating procedures that contain viable SARS-CoV-2, and these aerosols may serve as a source of transmission of the virus.

April 2020

"SARS-CoV-2 was also found to be transmitted via the air in two out of six ferrets21, and in two out of six cats. However, only low levels of SARS-CoV-2 RNA were detected in nasal washes and feces of the indirect recipient ferrets, and no infectious virus was isolated21. Furthermore, virus shedding was shorter as compared to the donor animals and only one out of the two SARS-CoV-2 RNA positive indirect recipient ferrets seroconverted. Similarly, the transmission via the air between cats was not efficient. " "No SARS-CoV-2 RNA was detected in the air sampled in three isolation rooms, or 10 cm from a symptomatic patient who was breathing, coughing or speaking. Nevertheless, RNA was detected on the air exhaust outlet of one of the isolation rooms in the first study, suggesting that virus-laden droplets may be displaced by airflows."

Also-- Coronavirus protection: How masks might stop the spread through coughs

Airborne pathogens - either transmitted via aerosol or droplets - include a wide variety of highly infectious and dangerous microbes such as variola virus, measles virus, influenza A viruses, Mycobacterium tuberculosis, Streptococcus pneumoniae, and Bordetella pertussis. Emerging zoonotic pathogens, …

Influenza viruses can spread through the air on dust, fibers and other microscopic particles, according to new research from the University of California, Davis, and the Icahn School of Medicine at

We provide evidence of a mode of transmission seldom considered for influenza: airborne virus transport on microscopic particles called “aerosolized fomites.” In the guinea pig model of influenza virus transmission, we show that the airborne particulates produced by infected animals are mainly non-respiratory in origin. Surprisingly, we find that an uninfected, virus-immune guinea pig whose body is contaminated with influenza virus can transmit the virus through the air to a susceptible partner in a separate cage. We further demonstrate that aerosolized fomites can be generated from inanimate objects, such as by manually rubbing a paper tissue contaminated with influenza virus. Our data suggest that aerosolized fomites may contribute to influenza virus transmission in animal models of human influenza, if not among humans themselves, with important but understudied implications for public health.