Study Suggests Powdered Climbing Chalk is Unlikely to Transmit COVID-19

Ninety-nine percent of infectious particles dissipated within one-minute of coming in contact with climbing chalk

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Researchers at De Montfort University Leicester in England have found that climbing chalk is unlikely to transmit COVID-19 or similar viruses, according to an article published by the university. The study was conducted by virologist Dr. Maitreyi Shivkumar, microbiologist Dr. Katie Laird, and postdoctoral researcher Dr. Lucy Owen. The research is in the process of being finalized and the team expects to publish a peer-reviewed paper by the end of the year.

For the experiment, the team dusted plastic surfaces with climbing chalk (magnesium carbonate, calcium carbonate, or a blend of the two) and added droplets of a model coronavirus, HCoV-OC43. They then measured how many infectious particles remained at regular intervals over the course of an hour. Within one minute of coming in contact with the chalk, 99% of infectious particles had deactivated. HCoV-OC43 was used in place of SARS-CoV-2 (the virus that causes COVID-19) because it has a similar structure and survival pattern.

“Rather than just looking at whether the virus was still present in the chalk, we wanted to explore if any virus that comes into contact with chalk still posed a risk of infection,” Dr. Shivkumar said. “We are really pleased that the findings of our study suggest that chalk powder inactivates the infectivity of the virus and is therefore unlikely to harbor coronaviruses like SARS-CoV-2.”

This isn’t the first study to demonstrate chalk’s effects on a coronavirus. Earlier this year, a team of researchers at the University of Colorado Anschutz Medical Campus found that 80% ethanol liquid chalk clears 100% of SARS-CoV-2 within five minutes

Both of these studies are good news for climbers. Not only is chalk unlikely to spread SARS-CoV-2 via surface transmission, but it may even reduce the risk of surface transmission. Nonetheless, climbers should still follow social distancing and sanitization protocols, as respiratory droplets pose the greatest risk.