If you’re still wiping down groceries, doorknobs and light switches in an attempt to thwart COVID-19, maybe you can relax a little: You’re 1,000 times more likely to get COVID from the air you breathe than from surfaces you touch, a new study suggests.
University of Michigan researchers tested air and surface samples around their campus and found odds are greater for inhaling virus particles than picking them up on your fingers.
“In this study, we set out to better understand potential exposures to the SARS-CoV-2 coronavirus — the virus which causes COVID-19 — in several college campus settings,” explains study author Richard Neitzel, a professor of environmental health sciences and global public health.
The settings included offices, classrooms, performance spaces, cafeterias, buses and a gym. However, the samples were taken during the pandemic lockdown, so these were relatively empty spaces.
“We also used information on campus COVID-19 infections to estimate the probability of infection associated with our environmental measurements,” Neitzel adds.
“The overall risk of exposure to the virus was low at all of the locations we measured,” he says.
However, “our results suggest that there was a much higher risk of infection from inhalation than from contact with surfaces like door handles, drinking fountains, keyboards, desks, sinks and light switches,” he notes.
Inhalation vs. contact with surfaces
To get a handle on relative risk, between August 2020 and April 2021 Neitzel and his colleagues used air pumps and swabs in various locales across the locked-down campus.
In all, more than 250 air samples were gathered, of which 1.6% tested positive for the virus that causes COVID. Of over 500 surface samples, 1.4% were positive.
The riskiest setting was the gym, with positive indications found for 75% of air samples and 50% of all surface samples. Most of the contaminated gym surfaces involved