CU Boulder researchers find dry air keeps COVID-19 virus alive longer than humid environments
New research from CU Boulder shows why people in Colorado may get sick from airborne viral diseases more often than those who live in humid climates.
Researchers at the University of Colorado Boulder campus have found that airborne particles carrying the COVID-19 virus remain infectious twice as long in drier air than in humid air. The study was published in December and shows that, in part, saliva emitted with those particles serves as a protective barrier around the virus, especially at low humidity levels.
Researchers believe this finding emphasizes the importance of managing indoor air filtration and ventilation to mitigate airborne disease spread in arid states like Colorado and dry enclosed environments like airplane cabins.
"The physics of the air in our buildings and the climate in which we live affect things that can make us sick and how long they persist. Now we have conservative indications of how long coronaviruses like the one that causes COVID-19 can stick around in the air and be an infectious disease threat," said Mark Hernandez, senior author and S. J. Archuleta Professor of Civil and Environmental Engineering, in a statement.
According to the research, At both 40% and 60% relative humidity, half of the airborne coronavirus particles were still infectious after aging for one hour in their testing chamber. But at 25% humidity, that time doubled: Half of the original particles released into the testing chamber remained infectious for two hours.
The researchers chose these humidity levels as civil engineers design and operate buildings in the U.S. to maintain an indoor relative humidity between about 40% and 60%. In comparison, Colorado hovers at an arid 25%.
Researchers say instead of humidifying indoor spaces, it may be better to focus on a different solution.
"Instead, we can add simple, inexpensive air filters that will take infectious particles out of the air faster," said Hernandez in a statement. "We can also increase the ventilation rate, open windows and make sure we get more fresh air."