Humidity and Virus Transmission: Searching for Solutions in the IoT

As researchers and government agencies around the planet attempt to reduce the spread of the COVID-19 virus, there is renewed interest in which conditions slow or inhibit viral spread and contagion. While previous work has investigated other pathogens such as influenza, COVID-19 represents a new virus with its own unique characteristics.

Previous questions about viral transmission in varying air humidity levels are being reopened with regards to COVID-19, and findings are showing some similarities to previous studies. Some recent research suggests there may be relative humidity levels at which viruses thrive and infect at a faster rate, as opposed to those at which they fall out of suspension, are less able to attack lung tissues, and are otherwise severely impeded.

This research is still among the earliest and needs more validation before it can be considered truly authoritative. But if it bears out, there may be a significant role to play for the Internet of Things in improving public health and safety. Smart sensors today already help track and report relative humidity and might help make environments safer for humans and less habitable for viruses. Automating the measurement and subsequent control of these air conditions could one day mean healthier people, lower disease rates, and saving lives.

Investigating Humidity and Influenza Transmission

This new research is not the first to seek for a causal relationship between air humidity and a virus’ ability to spread. One noteworthy study from 2013 entitled “High Humidity Leads to Loss of Infectious Influenza Virus from Simulated Coughs”, conducted by researchers for HELD, NIOSH, and the CDC, found a significant variance in the presence of influenza in simulated cough particles as relative humidity was changed. Their research found that the influenza virus retained 70.6–77.3% infectivity at a relative humidity of ≤23%, as opposed to 14.6–22.2% at relative humidity ≥43%.

The proposed reasoning for this follows from the behavior of aerosol particles as they leave the lungs and enter the air. In low humidity environments, those particles leaving the lungs meet with dry air, and give off some water as they homogenize into the environment. This means they become lighter, float in the air longer, and take much longer to fall out of suspension. Consequently, after one hour of measurements in this experiment, influenza particles were measured at 70.6 – 77.3% of their initial infectivity.

Alternatively, in high humidity environments, aerosol particles do not lose as much moisture, since there’s not a large imbalance to equalize. These particles remain heavier and fall out of suspension much faster. In fact, researchers claimed that within 15 minutes at 45% relative humidity, over 90% of the influenza virus ejected into the test chamber lost infectivity.

Humidity and COVID-19: Seeking a Reliable Method of Control

This connection between humidity and viral transmission may be a promising line of research as the world attempts to limit the movement of COVID-19. New research is suggesting the possibility that in environments of higher relative humidity, COVID-19 transmission may be less effective. A recent publication in the Annual Review of Virology entitled Seasonality of Respiratory Viral Infections claims that viruses are more successful in low RH (<40%) and high RH(>60%) environments, but that in intermediate humidity (40% - 60% RH), viruses are more likely to be inactivated.

All of this implies that environment may play a critical role in the behavior of viruses, which tracks with people’s experience of certain viruses in winter. Most people are familiar with the wintertime increase in certain seasonal viruses, such as influenza, HCoV, and RSV. Cold temperatures and HVAC systems tend to produce extremely low relative humidity in people’s homes, which may be responsible for creating an environment where viruses spread.

Dry air also affects the body’s respiratory tissues, such as the lungs and esophagus, where viruses attach and replicate. Low air humidity causes those tissues to be drier, removing the moisture and surface flexibility that helps cilia clear intruders and protect the underlying tissue from infection.

A Hopeful Future: How IoT May Help Fight COVID-19

So what does this mean for the IoT today? In short, not very much yet: it’ll be necessary for multiple studies to demonstrate repeatability and viability of these ideas, and only with subsequent confirmation will a fuller picture emerge. The scientific community is very far from a complete understanding of the best approach for fighting COVID-19.

It’s not fully clear what strategies will prove the most effective, but if controlling humidity and temperature prove to be effective strategies, the IoT can provide easily-deployed smart solutions that will improve public safety.  

Monitoring small and large facilities for humidity with a deployment of wireless sensors is an easy way to gain actionable intelligence with minimal setup. Our RS1xx wireless temperature and humidity sensors are easy to install, run on two AA batteries, and are easily configurable by smartphone. Several sensors can all connect via one central gateway anywhere over LoRaWAN up to 10 miles away, and that temperature and humidity data can be logged in the cloud, tied to alerts and actions, and can be logged for long-term reports on change over time.

It’s easy to deploy multiple sensors and connect them all up to the cloud via our RG1xx LoRaWAN gateways. Our RG186 and RG191 gateways provide a route for LoRaWAN data up to the cloud via Wi-Fi and ethernet. Also available with IP67-rated outdoor housing, the RG1xx provides a reliable, easy-to-use gateway for your critical sensor data.

The future of the battle against COVID-19 is not clear. More is yet to be learned about what strategies and tools can be used to decrease the virus’ spread. But around-the-clock automated IoT solutions are sure to play a significant role in that fight, enabling safer living and work spaces, helping track infection and limit exposure.

For more on our IoT devices and gateways, visit our IoT Devices page.