Bleach Plus Sweat Means Gyms Need Especially Good Ventilation Interview with:
Zach Finewax, PhD
Research Scientist I
Cooperative Institute for Research in Environmental Sciences (CIRES)
National Oceanic and Atmospheric Administration (NOAA)
Chemical Sciences Laboratory (CSL)
Chemical Processes and Instrument Development (CPID)
University of Colorado, Boulder, CO What is the background for this study?

gym-exercise-sweat.jpegResponse: Humans on average spend 90% of their time indoors. As a result, they are exposed to indoor air far more often than outdoor air (the atmosphere). Yet, the chemistry (and air quality) of the atmosphere has been studied far more often than indoor air. Air quality is linked to direct health impacts, and the emissions indoors can be ventilated outdoors where they can undergo chemical transformations that have climate and health impacts.

Beyond exposure to indoor air, humans contribute significantly to overall indoor air quality by breathing, sweating, and applying personal care or hygiene products. Previous studies have investigated these emissions at a high level of chemical detail for seated or standing individuals indoors, but limited chemical and time-resolution studies have been conducted while people are exercising indoors. What are the main findings?

cleaning-bleachResponse: The studies main findings were:

  • VOC emissions related to metabolism or emitted directly from the human body were elevated, on average 3-5 times higher than from individuals at rest. These emissions correlated with carbon dioxide, which was also elevated by 3-5 times compared to a resting individual.
  • VOC emissions related to personal care products were not significantly higher from exercising individuals than at rest.
  • Reactions of amino acids from sweat with bleach on surfaces led to the formation of N-chloraldimines, which were observed for the first time in room air. What should readers take away from your report? What is the significance of the N-chloraldimines products? 

Response: Readers should pay attention to the ventilation in indoor environments, particularly gyms where emissions are elevated. Concentrations of VOCs indoors are typically elevated compared to outdoors, and this is related to the fact that indoor environments do not have strong air currents to transport emissions away from the source. Improved ventilation helps remove emissions outdoors, reducing exposure to elevated levels of VOCs.

N-chloraldimines demonstrate the reactivity of bleach indoors, and may have direct health impacts. These compounds further demonstrate the impact of human emissions indoors, as those that are not volatile enough to remain in the air (i.e. amino acids) may deposit on surfaces where they are available for surface reactions with bleach. What recommendations do you have for future research as a result of this work?  

Response: It will be important to determine the health impacts of N-chloraldimines, which are currently unknown. Determining how specific factors of exercise (type, duration, intensity) affect emission quantities will be important to understand and estimate air quality in different indoor environments.


Finewax, Z., Pagonis, D., Claflin, M.S., Handschy, A.V., Brown, W.L., Jenks, O., Nault, B.A., Day, D.A., Lerner, B.M., Jimenez, J.L., Ziemann, P.J. and de Gouw, J.A. (2020), Quantification and source characterization of volatile organic compounds from exercising and application of chlorine‐based cleaning products in a university athletic center. Indoor Air.

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Jan 9, 2021 @ 8:38 am 

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