If you’ve been to a live concert or stage play, one of the coolest effects is “smoke.” A shallow pool of white smoke covering the stage creates a surreal visual experience. Smoke can also be released from above the stage where it makes lighting effects like lasers more visible to the audience.
What you may not know is that many of these smoke effects are created by quickly releasing liquid carbon dioxide (CO2) into the air. As the CO2 liquid expands to a vapor, it condenses the moisture in the air and creates the smoke effect.
The benefits of CO2-based smoke or fog is that it is tasteless, odorless, and quickly dissipates into the air. However, concert “smoke” effects created using liquid carbon dioxide (CO2) can pose a hazard to the public and venue staff if used in improperly ventilated areas.
As we've detailed in past articles restaurants and bars use liquid CO2 to put bubbles in soda and beer. These business store the liquid CO2 in bulk storage vessels or in high pressure cylinders. Event venues store the same gas in the same way. However, unlike using CO2 to carbonate drinks, in concert venues it is released into the air. As CO2 is heavier than other gases and normal air it will collect on the floor and over time fill an enclosed space.
While a small rise in CO2 levels is not noticeable or harmful, at concentrations up to 1% (10,000 ppm) it will make some people feel drowsy. Concentrations between 1% and 5% can cause dizziness, headaches, visual impairment, and unconsciousness in as little as a few minutes. And according to the National Institute of Occupational Safety and Health (NIOSH) concentrations above 5% (50,000) may cause asphyxiation, even in the presence of sufficient oxygen
CO2 Risks in Concert Venues
When used properly and according to the manufacturer’s specifications CO2 effects equipment used at event venues are safe. However, as in any application that uses CO2 in enclosed spaces, human errors can occur. For example, a theater technician at the Smokey Mountain Opry Theater in Pigeon Forge, TN died earlier this year and two other technicians were sent to the hospital due a CO2 gas leak during a performance. Authorities later discovered that a safety valve was left open on the effects equipment.
Even at lower concentrations, the risk for high levels of CO2 in enclosed venues poses a risk. For example, a study at the University of Iowa showed that heightened CO2 levels changed the acidity in the brain which plays an essential role in the fear response. Several of the experiments described in the Iowa paper showed that inhaling air with high levels of CO2 triggered strong fear reactions in mice. CO2 levels in an event venue will rise naturally over time due to normal audience respiration. Imagine combining rising CO2 levels with CO2 effects? Now imagine an unanticipated emergency and the sudden rush of attendees towards the exits.
CO2 Safety Alarm
To protect against high levels of CO2 in concert venues and theaters, our Remote CO2 Storage Safety 3 Alarm is the best solution. It is designed to protect customers and workers near stored carbon dioxide. Because it meets all NFPA, IFC, and NBIC requirements as well as the OSHA and NIOSH time-weighted average (TWA) standard for employees, the alarm will not only protect audience members, but will protect staff in case a CO2 leak occurs. The addition of CO2 Storage Safety Strobe Towers can make it easy to determine instantly if CO2 levels are rising.