Writing in the recently published “Journal of Exposure Science and Environmental Epidemiology”, scientists in the United States pointed out that after testing samples collected from the air and surfaces around campuses, they found that the probability of people contracting the new coronavirus from the air they breathe is 1000 times the infection from touching surfaces.
Between August 2020 and April 2021, University of Michigan environmental health sciences and global public health professor Richard Naizer and colleagues collected samples using gas pumps and swabs at various locations on the enclosed campus. In total, they collected more than 250 air samples, of which 1.6% tested positive for the new coronavirus. And of the more than 500 surface samples, 1.4% were positive.
The results showed that the most dangerous environment was the gym, where 75% of the air samples and 50% of the surface samples tested positive. None of the samples were positive. Also, samples taken from an office or computer keyboard, light switch, table top, microwave oven, refrigerator handle, or student desk are much less likely to be positive.
The researchers then compared the positive samples to actual Covid-19 cases on campus and found that the probability of contracting airborne Covid-19 particles was about 1 in 100; the probability of contacting contaminated surfaces was 1 in 100,000. The former is 1000 times the latter.
“Our findings suggest that exposure to the virus from the air is much higher than the risk of contracting the virus from surfaces such as doorknobs, drinking fountains, keyboards, desks, sinks and light switches,” Naizer said. While school settings may not be the same as other settings, our findings suggest that people should be more concerned about the risk of inhalation of coronavirus.”
Elizabeth Scott, a professor emeritus at Simmons University who was not involved in the study, said: “There is a growing recognition that Covid-19 is primarily airborne.” But she also cautioned that “when people live together and come into contact repeatedly, The relative chance of COVID-19 transmission through surfaces is also high in homes and dorms on the same surface, and the latest study did not assess this private space risk.”
She further pointed out that it is worth noting that “other respiratory viruses and other bacterial infections are mainly transmitted through contact surfaces, and we need to continue to implement effective and comprehensive hygiene measures on surfaces and the air to prevent the spread of the new coronavirus in the community”.