Before demolition can take place, all air conditioner units on the premises must be professionally degassed. Under the Ozone Protection and Synthetic Greenhouse Gas Management Act of 1989 it is an offence to unlawfully discharge air conditioner gases and harsh fines apply for committing such offences.
Air conditioner units contain either R22 gas or R4 gas. Both these gases require a licensed professional to remove. New machines, those made in the last 2-3 years, contain R4 gas which can be recycled, while older machines contain R22 gas, which must be disposed of.