Health effects study
Different types of fog and haze machines are used in theatrical productions depending on the type of effect desired – a short burst of smoke that quickly dissipates; a lingering haze to enhance lighting effects; a rolling fog across the floor. Different types of chemicals are used to produce these different effects, such as glycols, glycerin or mineral oil. To evaluate the potential impact of exposure to these chemicals, we conducted a health effects study involving 218 actors from 16 Broadway musicals. The study included a detailed exposure assessment, as well as clinical evaluations of actors before and after performances.
Study results revealed no evidence of serious health effects associated with exposure to theatrical fog and haze. Peak exposures to elevated localized air concentrations are associated with increased reporting of respiratory, throat and nasal symptoms, and findings of vocal cord inflammation. Other factors besides theatrical effects were also found to be associated with increased symptom reporting, such as perceived levels of stress (at work and away from work), performance schedule, and physical demand of the actor’s role. Following the study, our experts developed peak exposure guidelines to mitigate these acute irritant effects on actors’ respiratory or vocal cord health.
Subsequent work for productions and equipment manufacturers
The peak exposure guidelines developed during the health effects study were adopted as the industry standard. Productions must collect and report data from fog machines and fluids to demonstrate compliance with these guidelines. To facilitate this testing, Ramboll has been working with the manufacturers of fog machines and fluids to develop calibration factors and other data that productions need to meet this requirement.
Ramboll has also become the primary resource for theatrical productions that need assistance in keeping exposures to theatrical fog below the peak exposure guidelines. We have also provided similar services for movie and television productions and concert venues. We perform testing of the scenes in which fog effects are used, and when exposures are above the guidelines, we work with the productions on changes to the choreography or the way the fog machines are used to achieve acceptable results.