The issu wastee of proper disposal of aerosol spray cans can be a tricky one. If you have a partially empty aerosol can and you decide to dispose of it, you have yourself a RCRA solid waste. You must then determine if this solid waste meets any of the four characteristics (ignitability, reactivity, corrosivity and toxicity). If the content in the can is not toxic, ignitable or corrosive, you still have to deal with the issue of reactivity.
A partially pressurized can is reactive because it can explode under certain conditions such as high temperature. Therefore it is a solid waste that exhibits one of the four hazardous waste characteristics and it is a RCRA hazardous waste. In fact, inspectors in California have been known to do dumpster dives just to look for this type of aerosol cans.
The issue of puncturing aerosol spray cans is even trickier. Some argue that the act of puncturing the can and recovering the product in it constitute recycling activity and is exempt from RCRA regulations. Others (some agencies) will argue that puncturing a can constitutes on-site treatment of hazardous wastes and a special permit is required.
RCRA’s definition of “treatment” as stated in 40 CFR 260.10 includes “any method, technique, or process ….designed to change the physical, chemical, or biological character or composition of any hazardous waste ……..so as to render such waste nonhazardous, or less hazardous….”
The prudent way is to dispose of pressurized aerosol cans as hazardous wastes unless you get a definitive ruling from your state agency on puncturing.