Dec 2020. *****!!!!!****!!!*** We find SARS-CoV-2 survives longest at low temperatures and extreme relative humidities; median estimated virus half-life is over 24 hours at 10 °C and 40 % RH, but approximately 1.5 hours at 27 °C and 65 % RH."

***!!!!******!!!!!***** "We investigated the effects of RH on the viability of bacteria and viruses in both suspended aerosols and stationary droplets using traditional culture-based approaches. Results showed that viability of bacteria generally decreased with decreasing RH. Viruses survived well at RHs lower than 33% and at 100%, whereas their viability was reduced at intermediate RHs. We then explored the evaporation rate of droplets consisting of culture media and the resulting changes in solute concentrations over time; as water evaporates from the droplets, solutes such as sodium chloride in the media become more concentrated. Based on the results, we suggest that inactivation of bacteria is influenced by osmotic pressure resulting from elevated concentrations of salts as droplets evaporate. We propose that the inactivation of viruses is governed by the cumulative dose of solutes or the product of concentration and time, as in disinfection kinetics."

"The total airborne mass fraction was between 2.7% and 32.2% of the mass emitted from the bottle, depending on the product. Between 0.0001% and 0.01% of the total airborne mass fraction consisted of residual particles. However, these particles had a mass median aerodynamic diameter between 1.9 µm and 3.7 µm, constituting a total respiratory deposition of up to 77%...Thus, the use of cleaning sprays can result in chemical airway exposure, with particles in the relevant size range for both nasal and alveolar deposition"

{Problems related to air pollution, climate, etc} Geo-environmental determinants of the accelerated diffusion of COVID-19 that is generating a high level of deaths. The second is to suggest a strategy to cope with future epidemic threats.

(2005). {Includes other useful links} Toward Understanding the Risk of Secondary Airborne Infection: Emission of Respirable Pathogens. Journal of Occupational and Environmental Hygiene: Vol. 2, No. 3, pp. 143-154.

Coronavirus disease 2019 (COVID-19) has become a global pandemic. Its relationship with environmental factors is an issue that has attracted the attention of scientists and governments. This article aims to deal with a possible association between COVID-19 ...

A review of the scientific literature aimed at providing a better understanding of aerosols and droplets, and their importance in airborne spread of disease. "Even when a virus can be spread through airborne transmission, you are still much more likely to become ill as the result of close contact. If COVID-19 is transmitted similarly to influenza, we can be somewhat reassured by our current practices."

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 (

***"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"

Includes analyses of effects of humidity on transmission

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.

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.

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."

April 2020

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.