Research on the Relationship Between Air Humidity and Aerosol Transmission of COVID-19

Research purposes

This study aims to examine the impact of different environmental control strategies, such as ventilation, relative humidity, and other factors, on the viral load suspended in the air to determine which strategy to use to minimize the spread of the virus.

Research methods

A sealed modular laboratory equipped with air samplers, humidifiers, dehumidifiers, HEPA filters, settling plates, particle counters, a standing desk, and a treadmill. After two months, 11 University of Oregon students diagnosed with the COVID-19 coronavirus were simultaneously stationed in the room and invited to participate in a three-day experiment where they sat, stood, spoke, and coughing on purpose, walked on a treadmill, etc.

For each day of the study, the researchers will measure viral RNA in the air and on surfaces, as well as viral RNA extracted directly from the nasal and oral cavities of the participants. The idea is to measure how virus particles move through the air with three environmental control variables: ventilation, filtration, and humidity.

Experimental results

Increased viral loads in nasal samples were associated with higher viral loads collected in the environment, including ambient aerosols in the near zone (1.2 m) and far zone (3.5 m) and surfaces.

The far-field viral load was correlated with the number of particles in the 1–2.5 µm range.

Increased ventilation and enhanced filtration can significantly reduce viral loads in aerosols and surfaces.

High relative humidity results in lower aerosol and higher surface viral loads, consistent with higher particle deposition rates at high relative humidity.

Experimental data from high-frequency respiratory activity in the near area suggest that the volume of respiratory particles of smaller size (0.3–1 µm) best characterizes changes in aerosol viral load in the near area.

Professor Kevin Van Den Wymelenberg, who carried out the study, commented that the most exciting experimental result is that higher relative humidity can encourage virus-carrying particles to break out of the air and settle on surfaces. From a particle physics perspective, it makes perfect sense, he says, "the higher the relative humidity, the higher the moisture content in the air, the faster the particles settle." After the particles settle to the ground, most can be removed by conventional cleaning methods such as sweeping and wiping, effectively inhibiting the spread of bacteria and viruses.

"Moderate relative humidity, between 40% and 60%, is probably the best condition for removing virus particles from the air," Prof. Van Dem added. Air that is too humid increases the risk of mold, while air that is too dry causes dry particles to float longer. Humid air is also good for the immune system because it helps keep the mucous membranes healthy and moist. It causes dry particles to float longer. Humid air is also good for the immune system because it helps keep the mucous membranes healthy and moist.

Humidifier Manufacturer

Smillon is a customer-oriented organization that’s heavily focused on comfort and health. We believe that our high-quality products enable us to bring ever-greater comfort and health to our customers; this helps establish our brand as a successful industry leader. Smillon is proud of its belief as an innovator in air care products that motivate us to overcome current limitations, pain points, and difficulties in the industry, time and time again.

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Jelly Wang

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