Since the spread of the SARS-CoV-2 (coronavirus) and subsequent nationwide shutterings of climbing gyms, many in the climbing industry have proposed innovative ways to mitigate risk of coronavirus, including the use of liquid chalk, given its alcohol content.
But will liquid chalk actually help?
The short answer is maybe, but not in the way you’d expect.
First, a look at what makes disinfectants work.The Centers for Disease Control (CDC) and World Health Organization (WHO) suggest that isopropyl alcohol (IPA)-based disinfectants are most effective in the 70-80% range by volume, with the other 20-30% being water. The science explaining the role of IPA and water in killing viruses is complicated. However, generally speaking, the presence of water slows the evaporation of IPA, which provides more time for the IPA to come into contact with virus cells. Water also aids IPA in penetrating the virus cell, which is necessary for IPA to kill the virus. Additionally, the CDC notes that when hands are heavily soiled or greasy, alcohol-based hand sanitizers are likely less effective, and handwashing with soap and water is recommended.
Liquid chalk is typically a suspension of high quality magnesium carbonate (MgCO3, a.k.a chalk) in IPA. When applied to one’s hands, the IPA evaporates rapidly, leaving behind an even distribution of chalk. A secondary phenomenon from the evaporating IPA is a cooling of the surface of one’s hands. The combination of dry and cool hands is obviously very beneficial for climbers. However, in late April 2020 a Department of Homeland Security report released preliminary lab study results indicating that coronavirus has a higher survival rate in cool dry environments.
Common commercial liquid chalks typically contain 40-50% IPA and MgCO3. This concentration is well below the 70-80% IPA concentration recommended by the CDC and WHO. In addition to the alcohol content being insufficient, any water present in the liquid chalk will be rapidly absorbed by the chalk, rendering it ineffective at aiding the IPA in destroying the virus. However, companies are beginning to produce liquid chalk with IPA concentrations in excess of 70%. The increased IPA concentration may provide some increased effectiveness as a disinfectant, however, those products would still lack unbound water required to slow the evaporation rate of the IPA, and to facilitate the IPA in entering the virus cell. Climbers are likely to apply fresh liquid chalk to dirty chalk laden hands throughout a session. As noted earlier, IPA based disinfectants lose effectiveness if the hands are not free of dirt and grime. Currently, there is no conclusive evidence to support the effectiveness of the use of liquid chalk as a disinfectant.
However, the use of liquid chalk may help for a different reason. A 2012 study published in the Journal of Environmental Monitoring reported a significant decrease in airborne chalk in climbing gyms with the use of liquid chalk. In a crowded gym, climbers breathe in elevated levels of chalk dust during a session. As highlighted by the study, most of that excess chalk dust comes from the use of loose chalk. While that exposure may have inherent health impacts on its own, the airborne chalk provides another potential surface for coronavirus to exist on. A recent study published in the New England Journal of Medicine found that coronavirus is detectable on atmospheric aerosols for up to three hours. Atmospheric aerosols differ substantially from airborne chalk, and the lifetime of coronavirus has not been studied on airborne chalk. However, even if the lifetime of coronavirus on airborne chalk is on the order of minutes, that still could possibly provide another method for coronavirus to enter a climber’s body at the gym. The reduction of airborne chalk from the use of liquid chalk is a potential benefit in regards to reducing coronavirus exposure and spread in a climbing gym. However, this is not currently supported by any rigorous science.
In order to evaluate the effectiveness of liquid chalk in mitigating coronavirus exposure, we need to also consider general climber behavior while climbing in the gym. To do so, let us assume that liquid chalk has some efficacy in killing coronavirus. Climbers are unlikely to apply fresh liquid chalk between every attempt on a boulder, route, or hangboard/campus board attempt. IPA is only effective at killing viruses on a surface before it evaporates. A climber will apply liquid chalk to their hands, wait for it to dry, and then pull onto a boulder or route. Between drying their hands and pulling onto the wall a climber may breath on their hands, touch their face or block a cough. Additionally, a person climbing at or near their limit tends to breathe deeply, often in close proximity to the holds on a wall. This behavior may apply a layer of virus-laden aerosols on the surface of the holds. Since the IPA from liquid chalk has already evaporated from a climber’s hands, it is completely ineffective in killing any potential viruses on the climber’s hands, and more importantly, on the holds on the wall.
Furthermore, plastic surfaces have been shown to harbor detectable levels of coronavirus for up to two to three days. Holds are not only plastic, they’re porous and potentially dirty, both of which are factors that may extend the life of the virus. Without directly disinfecting those climbing holds, the next climber to touch those holds could possibly now transfer viruses to themselves or to others, as they are unlikely to apply liquid chalk to their hands after getting off the wall.
Climbing gyms, like other indoor environments with ample shared surfaces, will have inherent risks in regard to the spread of coronavirus. The use of liquid chalk will not be the “silver bullet” in keeping indoor climbers safe from coronavirus. However, by following local and national guidelines for hygiene and social distancing, climbers can minimize those risks in the gym. Those recommendations include:
- Observing common distancing standards of a 6-foot radius when possible
- Limit the number of climbing partners and try to maintain consistent partners from session to session
- Wash hands often throughout a session with soap and hot water, especially after coughing or sneezing
- Minimize touching one’s face while in the gym
- Wearing at least a basic cloth mask even if it is not required
- Minimize touching surfaces unnecessarily
Most importantly, follow the guidelines and rules set by your gym, and be patient as gyms try to figure out how to best keep their customers and employees safe and healthy as they reopen. Gyms will likely have to come up with novel operation protocols such as climbing by reserved time-slots or staggered hours throughout the day for targeted cleaning. These protocols and distancing/hygiene recommendations will be frustrating for the gym owners, employees, and customers. Nonetheless, these measures will help to keep people at the gym and the surrounding community safer and healthier.
This article was written with the help of the Climbing Wall Association (CWA). The CWA’s official statement is: “Liquid chalk has a lot of positive benefits above and beyond the current pandemic. At proper concentrations it may even allow an extra level of comfort and security when returning to your climbing gym. However, it should not be used as the only method of protection when returning to the gym and you should follow all of the policies your gym has carefully crafted to manage the risks of reopening.”
Feature image source.