Chalk Dust in Climbing Gyms: Guide to Better Air Quality

In a previous article, The Climbers' Clinic exposed potential health risks linked with climbing chalk dust in indoor climbing gyms. It was shown that magnesium carbonate dust concentrations largely surpass all environmental and governmental ambiant air standards.

Due to their sub 10 micron size, magnesia dust particles are small enough to deposit in the lungs gas exchange region.  Symptoms such decreased expiratory lung function was documented and industrial product safety notice report respiratory tract irritation, coughing or shortnerss of breath as a result of exposure. (1)(2) Moreover, a portion of magnesium carbonate particules are smaller than 2.5 microns, to which no safe level exist; meaning that health adverse effects can occur at any exposure level (3). This is a concern with more kids participating in indoor rock climbing as well a people from diverse health backgrounds. According to the EPA (United States Environmental Protection Agency) indoor particulate matter concentration would be expected to be the same as, or lower than, outdoor levels. (4)

The Climbers' Clinic has prepared a list of healthy behaviours for climbers and strategies for gym owners in order to improve indoor air quality in climbing facilities.

Individual responsibilities

What strategies were proven beneficial?

Weinbruch et al (2012) tested several magnesia dust reduction strategies: ban climbing chalk use,  liquid chalk only, block chalk only, powdered chalk, sieved chalk and chalk balls only. According to their results, liquid chalk use and no chalk at were both very effective in keeping dust levels low. A reduction of 70% of dust concentration was measured with either one of these conditions. It was even more effective than turning the ventilation system on! (5)

Adapted from Weinbruch et al. (2012) Dust concentration per climber were calculated in order to compare different gyms. We added the data from the ventilation system. 

Furthermore, climbing gym rules limiting the use of a certain type of climbing chalk over another (powdered or sieved vs ball) are not supported scientifically. Block chalk, powdered chalk, sieved chalk and chalk ball ALL yield similar level of magnesia dust concentration in the air. 

Now, what can gym owners do to improve air quality in their facilities? Upgrading the ventilation system and reduce climbing chalk use are the two best measures, along with dilligent cleaning procedures.

Gym owners responsibilities

Again, what is the efficacy of such measures?

Castro et al (2015) were able to determine that cleaning operations at the end of the day (before closure) reduced  the concentration of magnesia at about 90% of their level during the day. (5) PM 2.5 and PM 10 continue to decrease 4h after cleaning procedures. 

Fine particules however, take up to 14 hours to deposit. Castro et al (2015) and Alves et al (2015) both were able to quantify that resuspension of dust particles (previously deposited) is a major source of air pollution.(5)(6).Thus, cleaning activities prior to facilities opening can help reduce a significant portion of magnesia dust by preventing its resuspension. The authors suggest the use of powerful vacuum cleaners with HEPA filters.

In addition, choosing nylon or vinyl bouldering matress is preferable over carpet-like surfaces.  The authors showed that foam, carpet or other porous surfaces trap dust and are harder to clean throrougly. When a climbers falls on a dusty "carpet finish" bouldering mat, the dust resuspension phenomenon is quite visible. 

What about air filtration devices? While two previous authours sugested the use of adequate air filtration systems, Almand-Hunter et al (2013) tested the efficacy of various air filtering strategies. (8) 
Their team measured the effect of compact air filters and electrostatic precipitating air cleaners. Their preliminary results show that the buiding ventilation system is the only effective way of reducing magnesia dust concentration in the gym. There was no impact on air quality in adding air filters in the reception area, the gym office or adding 5 electrostatic precipitating air cleaners throughout the gym climbing area. In comparison, running the air conditionning ventilation system reduced magnesia dust concentration to 70% of baseline levels. The ventilation system had a rate of 7.1 total gym air volume renewal per hour. 

Weibruch et al (2012) evaluated that a poweful ventilation system can reduce 40 to 60% of dust concentration compared to baseline values (see graph above). They tested a ventilation system that had a air exchange rate of 8100 m³ per hour: the gym's total air volume was renewed 1.5 times in an hour. The other studied ventilation systems, which  air exchange rate were 2000 or 4000 m³ per hour,  failed to reduce dust concentration in their respective gyms. 

Due to building constraints, climbing gyms may still opt for filtering systems, but owners must ensure that they are designed for particles in the 1 micron size. Moreover, filters might need to be replaced or cleaned more often thant the manufacturer's indication. For instance, some devices were designed for gymnastic facilities, where dust concentration is never as elevated as in climbing gyms. Maximal magnesia dust concentration in gymnastic halls can reach 900µg per m³ but can get as high as 4000µg par m³ in climbing gyms! (6)(7)(9) As a matter of fact, dust concentrations in climbing gyms are similar as the ones measured in the textile, mining or chemical industries! (9) Fortunately magnesium carbonate has a low loxicity... 

In conclusion, there is only two effective strategies to keep air quality in climbing gyms. The first one is that each climber limit their climbing chalk use, use liquid chalk or learn to climb without chalk althogether. The second effective measure is for gym owners to invest in a powerful ventilation system with sufficient air exchange rate in relationship to their gym air volume. Meticulous daily cleaning also help prevent resuspension of dust particles.

According to Health Canada: "the most effective way to reduce indoor air pollution is to remove or reduce the source of contamination." (10)  Air filters can help to reduce the amount of pollutants indoors but is rarely effecient as a stand alone measure. 

Lastly, before investing in costly air filtration systems, The Climber's Clinic would recommended to get an air quality analysis by independant firms. Many compagnies perform tests that measure precicely the level of fine particles and their composition. Long term solutions can then be implemented according to the gym's specific needs. 

Special thanks to Marie-Pier Breault from MDDLECC and Patrick Hughes from CCHST for their precious informations, Thibault Stimpling for scientific articles and  Milan Brlek for finding typos.



References

(1)Moshammer (2016) Lung function and dust in climbing halls. Rev Environ Health.31(4):401-407

(2) https://www.psh.ca/MSDS/Magnesium%20Carbonate%20-%20A&K%20Petrochem.htm
Hazard/Safety Labels for Chemical Containers

(3) Health Canada (2012) Guidance for fine particulate matter (PM2.5) in residential indoor air. https://www.canada.ca/en/health-canada/services/publications/healthy-living/guidance-fine-particulate-matter-pm2-5-residential-indoor-air.html

(4) EPA (n.a) Indoor Particulate Matter https://www.epa.gov/indoor-air-quality-iaq/indoor-particulate-matter#Levels_in_Homes

(5) Weinbruch, S. et al. (2012) Reducing Dust exposure in indoor climbing halls. Journal of Environmental Monitoring. 14, 2114-2120.

(6)Castro, A. et al. (2015) Indoor aerosol size distributions in a gymnasium. Science of the total environment 524-525, 178-186.

(7) Alves C. et al (2014) Particulate matter in the indoor and outdoor air of a gymnasium and a fronton. Environ Sci Pollut Res 21 (21) 12390-402.

(8)Almand-Hunter, B.B. (2013) Dust exposure in indoor climbing facilities, Department of Mechanical Engineering, University of Colorado, Boulder, CO

(9)Weinbruch S. et al (2008) Dust exposure in indoor climbing gyms. Journal of Environmental Monitoring. 10, 648-654.

(10)Health Canada (2018) Improve indoor air quality. https://www.canada.ca/en/health-canada/services/air-quality/improve-indoor-air-quality.html