Fog Machine - On Command
Perhaps use a small wireless board like the NRF24L01 (available for around $1 each on eBay). Have one at the fogging machine, similar to the Instructable, but instead of a sensor, you turn the machine on and off when a command arrives. For example, send "0" to turn it off and "1" to turn it on. There are examples with the NRF24L01 library.



Then you have an Arduino in the wings nearby where you press a switch when you need to turn the fogging machine on (this would transmit the signal).