2021 Yes https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8205592/ Shendell, Derek North America Observational Exposure Study High School (9-12) Temperature Humidity Carbon Dioxide (CO2) Particulate Matter (PM) Dust In summary, specific activities like takedown or pinning maneuvers within a bout combined with inadequate mechanical ventilation for the gym’s occupancy during matches led to higher indoor CO2 measures. Measured indoor CO2 concentrations in this study did not exceed the typical guideline of 1000 ppm [11] except during the 1/30/2019 varsity match when occupancy was higher than typical due to increased numbers of spectators. Also, neither thermal comfort nor fire code occupancy limits were exceeded, and, as schools are workplaces for adults, the measured indoor CO2 was below the occupational enforceable regulatory limit. In this study, we could not completely characterize the potential contribution to indoor PM of outdoor PM from the adjacent primary road and a freeway (US Interstate I-295) near School A. (e mechanical HVAC system may not have been set
or reset for the increased occupancy expected or realized, respectively, i.e., not enough outdoor air with a lower CO2 concentration was brought into the gym.