"With prehumidification, recovery rates (± standard deviations) were much higher for nonenveloped viruses (T7 coliphage, 28% ± 19% with prehumidification versus 0.02% ± 0.01% without prehumidification; poliovirus, 29% ± 5% versus 3.2% ± 1.8%) but were unchanged for enveloped viruses (Semliki Forest virus [SFV], 32% ± 7% versus 42% ± 8%; Langat virus, 42% ± 10% versus 51% ± 12%) Benbough attributed the inactivation of nonenveloped viruses to structural rearrangement during abrupt rehydration in the impinger collection medium and suggested that slower rehydration rates, such as those experienced during the prehumidification process, were more favorable for polioviruses and coliphages" "Viruses that partition on the surface of aerosols may be subject to damage due to surface tension, shear stress, and conformational rearrangement driven by hydrophobicity." "Results showed that enveloped viruses lost infectivity dramatically (up to four orders of magnitude) due to aeration, while the nonenveloped ones did not." "Higher RH allows for larger final aerosol size and larger surface area due to less evaporation and, thus, greater potential for surface inactivation of hydrophobic lipid-containing viruses (i.e., enveloped viruses). Nonenveloped viruses are less likely to be affected." "While salts appear to be toxic to enveloped viruses, addition of salts to the medium has been shown to improve rather than reduce the viability of nonenveloped viruses... Benbough (1) suggested that salts can slow the rehydration process ... and thus reduce the chance of structural rearrangements that can be damaging in the capsid of nonenveloped viruses. Our interpretation of the enhanced viability is that salts can keep the aerosol and the virus in it from drying out completely at RHs above the ERH and thus reduce the chance of unwanted structural rearrangements during rehydration. This effect would benefit the nonenveloped viruses that need to retain their structural water; meanwhile, they are not susceptible to damage by salts, as are enveloped viruses."

Testing is needed beyond just for minimum approval, and needs to be application-type specific.

Comprehensive, user-friendly humidity calculator supporting all popular parameters including dew/frost-point, %rh, ppmV, moisture content and more.

A calculator that can calculate the relative humidity based on temperature and water content

{Wide variety of methods}This article aims to draw the attention of the scientific community towards the elevated risks of airborne transmission of diseases and the associated risks of epidemics or pandemics. The complexity of the problem and the need for multidisciplinary research ...

The review shows that ventilation has various positive impacts on health and productivity of building occupants. Ventilation reduces the prevalence of airborne infectious diseases and thus the number of sick leave days. In office environment a ventilation rate up to 20-25 L/s per person seem to decr …

{Characteristics & issues relevant to humidifier use} After 5 weeks of testing humidity and evaluating daily usability of 9 top products, we found one that stood out as the best humidifier.

Coronavirus disease 2019 (COVID-19) was first identified in China in late 2019 and is caused by newly identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Previous studies had reported the stability of SARS-CoV-2 in cell culture media and deposited onto surfaces under a limited s …

{Organizations that regulate. Analysis of reasons for humidity guidelines} Dear Rapid Response: At our institution, we recently encountered an issue with our HVAC system that left the operating room humidity at approximately 70%. Our operating rooms were closed because...

Study of respiratory infections in nursery school children in humidified and non-humidified environments. Humidification to 50%RH reduced infections by half.

{Ways to improve home air quality.} This virus is transferred from person-to-person and can be airborne. You might think an air purifier could reduce exposure. Let’s check out

********Laboratory research studies indicate that aerosolized influenza viruses survive for longer periods at low relative humidity. "indicates that increased humidification decreases survival of influenza virus on surfaces " "The median air exchange rate of the models was essentially the same, approxi- mately 0.22 air changes per hours (ACH). However, due to lower air movement between rooms, radiant heat models showed larger increases in moisture levels, and therefore larger decreases in influenza virus. In a similar way, home characteristics such as the room volume and air exchange rate should be considered"

"National Institutes of Health recently conducted a study to determine the risk to health of their humidifier policy.37 The policy allows patients to request bedside humidifiers, but states that humidifiers “must be filled with sterile water and that the humidifier must be discarded after three days of use.”"

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The role of relative humidity in the aerosol transmission of influenza was examined in a simulated examination room containing coughing and breathing manikins.Nebulized influenza was coughed into the examination room and Bioaerosol samplers collected ...

"ABS plastic is used in the production of diffusers because they are made out of oil-based resources and boast of a much higher melting point (more temperature resistant) than PP plastic. As such, they cannot be broken down or corroded by the acidic chemical composition of some essential oils." "Plastic aside, other components of a diffuser like the metal atomizer and absorption rings are specifically designed to withstand the corrosiveness of essential oils." "Diffusers are much more powerful than humidifiers. They break down essential oils into an ultra-thin fragranced mist that's easily dispersed over a wider distance for longer periods. The cool or warm mist generated by humidifiers from the vaporization of water molecules is only able to travel over shorter distances. This low dispersion range is because humidifiers usually have larger atomizer, which subsequently produces bigger, thicker, and heavier mist concentration."

****Inactivation of an airborne virus is directly related to the relative humidity and temperature

Permeability or materials, humidification average per occupant, etc.

Climate control, air conditioning, understanding how we keep cool and the relationship between temperature, humidity and dew point including a dew point chart and comfort zones