Fog machines

Read this desription of how smoke detectors work, they can be triggered by smoke from a water based smoke machine, it depends on the concentration of the smoke http://www.systemsensor.com/pdf/A05-1003.pdf We all have different physioligies so it is possible, although extremely rare, to cause an athsma attack with heavy concentrations of smoke, you need to check material safety data sheets for all details http://www.fairlight.nl/Data/manual/Jem/ZR%20Mix.pdf That is why it is a wise precaution to advise patrons of the use of smoke machines in a production.